Plant Checklist

CHECKLIST OF THE VASCULAR PLANTS OF PLUMMERS ISLAND, MARYLAND

Authors: Shetler, Stanwyn G., Orli, Sylvia S., Wells, Elizabeth F., and Beyersdorfer, Marcie Source: Bulletin of the Biological Society of Washington, 14(1) : 1-57 Published By: Biological Society of Washington URL: https://doi.org/10.2988/0097-0298(2006)14[1:COTVPO]2.0.CO;2

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Stanwyn G. Shetler, Sylvia S. Orli, Elizabeth F. Wells, and Marcie Beyersdorfer

INTRODUCTION functions. The island was dubbed Winnemana, mean- Plummers Island and Mainland ing ‘‘beautiful island’’ in a local Indian language, and the cabin, Winnemana Lodge. Each year some of the Њ Ј Љ Њ Ј Љ Plummers Island (38 58 10 N lat., 77 10 36 W income from the investments is used to support re- long.) is a small wooded island in the Potomac River search on the island or elsewhere in the DC area near Cabin John, Montgomery County, Maryland within the Potomac drainage. (Figs. 1, 2). It is about 14.5 km (9 mi) upriver (north- The island is elongate and tadpole-shaped; its long west) from the White House, Washington, DC, and axis is oriented more or less east-west, with the west is just downriver from the American Legion (Cabin or upstream end being the broad, blunt end. It is high- John) Bridge of the Capital Beltway (I-495), which centered and rocky with large boulders outcropping connects Maryland and Virginia. The island is sep- at various places and a narrow primary floodplain arated from the Maryland shore by only a narrow and/or mudflats around parts of it. There is an abrupt, channel, which can be crossed at the east end on high outcrop (‘‘Rock of Gibraltar’’) at the west end, stepping stones except at high water. It lies between and there are two high knolls in the center that are Locks 10 and 12 of the Chesapeake and Ohio (C&O) thinly covered with soil and drop down to floodplain Canal (Figs. 3, 4). In the past the island’s name was with varying degrees of steepness. The elevation at often written with an apostrophe, Plummer’s. the top of the higher knoll, where the cabin is built, The island itself consists of only 4.8 ha (12 acres), is over 36 m (120 ft) above sea level and about 20 but it has been well known to local biologists for over m (some 60 ft) above the river level. Parts of the a hundred years, thanks to studies there fostered by north and south sides are rock cliffs. The top of the the Washington Biologists’ Field Club (WBFC) since other knoll is about 3 m (10 ft) lower. The outcrop- it first leased the island from the owner in 1901 ping rock is granitic gneiss, which also outcrops on (WBFC Web site, www.pwrc.usgs.gov/resshow/ the mainland (Erwin 1981). perry/bios/WBFCHome.htm). The Club purchased it The mainland parcel, lying between the towpath of in 1908, along with ca. 14.2 hectares (35 acres) of the C&O Canal on the north and the Potomac River the ‘‘mainland,’’ as the land between the island and on the south and somewhat surpassing the island at the canal was dubbed by the early members. To this both ends, was acquired and fenced (McKenny & was added the Barton tract of ca. l.4 hectares (3.5 Ricker 1937) to protect the island from encroachment acres) in 1924, for a total of 15.6 hectares (38.5 and to preserve access, and it was actively used in a acres) of mainland. The Leland Barton tract extended number of ways in the early years (see below). Killip the Club’s mainland holding between the C&O Canal and Blake (1935, 1953), following Club tradition, in- and the Potomac River eastward from Rock Run to cluded the mainland in their study of the Plummers Lock 10. Island flora, but starred (*) the species found only on Access to the island at times of high water requires the mainland. At almost 16 ha, it is more than three a small boat, and for many years the Club has had times larger in area than the island itself. The highest its own boat for ferrying its members the short dis- point is a knoll as high as the highest point on the tance across the channel to and from the island for island. its annual fall and spring outings on the island. From time to time a dock has been constructed on one or History of Floristic Study both sides, referred to as the ‘‘ferry’’ dock, but sooner or later flooding has always destroyed it. From the outset, the Club has encouraged and spon- Ownership of the island and mainland property sored research on the flora and fauna of the island and passed to the National Park Service through a series adjacent mainland, and many scientific papers have of steps in 1958–1961, and the property later became resulted to date, including a series of 29 papers under part of the new C&O Canal National Historical Park the general heading ‘‘Natural History of Plummers Is- (NPS), opening the island to public access. In return, land, Maryland.’’ Twenty-five of the 29 have been the Club received a settlement sum from the U.S. published in the Proceedings of the Biological Society government, which it invested, and an agreement of Washington. One was published as a Special Pub- with the NPS that the Club could continue to do re- lication and three as two Bulletins of the Biological search on the island and adjacent mainland and to Society of Washington. Many other papers dealing at maintain and use the cabin (Figs. 5, 6) it had built least in part with the island have been published else- on the island in 1901 as the ‘‘Clubhouse’’ for Club where (see WBFC web site, www.pwrc.usgs.gov/

Downloaded From: https://bioone.org/journals/Bulletin-of-the-Biological-Society-of-Washington on 10 Jul 2020 Terms of Use: https://bioone.org/terms-of-use Access provided by Smithsonian Institution 2 BULLETIN OF THE BIOLOGICAL SOCIETY OF WASHINGTON on the south side by the Locks 10 and 12 and then toward Fig. 1. Map of Plummers Island and Mainland, Montgomery County, Maryland. Original property of Washington Biologists’ Field Club (WBFC) was bounded Potomac River. Boundaries on east,river west, (south) and from north these sides locks. are Dotted shown lines by represent thin paths. solid Numbers line 1–22 running refer along Chesapeake to and collecting Ohio sites (C&O) (see Canal p. and 22). towpath between

Fig. 2. Aerial photograph of Plummers Island and vicinity. Photo courtesy of U.S. Geological Survey.

Fig. 3. C&O Canal and towpath along south side of Canal near Lock 11, looking upstream (west). Towpath forms northern boundary of original Mainland property of WBFC. Path to Plummers Island cuts off to left just before towpath rises to top of lock. Photo by W. J. Kress.

Fig. 4. Narrow Channel of Potomac River between Mainland (right) and Island, looking upstream (west). Photo by W. J. Kress.

resshow/perry/bios/WBFCHome.htm, Biological (Fig. 7) collected 500 or more—Ellsworth P. Killip Studies). (847), Albert S. Hitchcock (597), and Emery C. The first specimens known to have come from Leonard (578). Neil Hotchkiss, with 477, was not far Plummers Island were collected by a number of per- behind (Fig. 7). Nearly half, 31, of the 67 collectors sons in the late 1890s, before the WBFC was in- have been members of the WBFC, and 25 of the 31 volved with the island. Waldo McAtee (McAtee file, have been botanists. Since some 65 botanists (exact WBFC archives) alludes to collections as early as the number depending on definition of ‘‘botanist’’) have 1870s in his notes, but none has been seen to confirm belonged to the WBFC during the course of its long this. Once the Club established its headquarters on history, this means that fewer than half of them have the island in 1901, collections began to accumulate contributed specimens to the Plummers Island col- and the herbarium of vascular plants was kept con- lections over the years. veniently on the island in the cabin. A running list Three of the most important collectors and stu- of species identified on the island and the mainland dents of the Plummers Island vascular flora were Kil- was maintained in a card file. By 10 August 1912, lip (1890–1968), Leonard (1892–1968), and Hotch- this totaled 538 species, according to a list copied kiss (1901–1994), whose collecting activities on the from the card file at that time, apparently by McAtee, island spanned 41 (1915–1955), 45 (1921–1965), and entitled ‘‘Spermatophyta of Plummer’s Island, Mary- 49 (1917–1965) years, respectively. Sydney F. Blake land’’ (McAtee file, WBFC archives). The herbarium (1892–1959; Fig. 7) also stands out, not for his col- and the card file were still housed in the cabin as late lecting but for his collaboration with Killip to publish as 1937 (McKenny & Ricker 1937), but at some time the ‘‘Flowering Plants and Ferns’’ in 1935. That pa- after that they were moved to safety at the Smith- per, the second contribution (No. II) to the WBFC’s sonian Institution, presumably because of the grow- series on the Natural History of Plummers Island ini- ing threat of theft and vandalism. There the herbari- tiated that year, followed a short introductory paper um and associated card file have remained. (No. I, Maxon 1935) and was really the first research Up to the present, at least 67 persons have con- contribution to the new series. It was also the first tributed one or more specimens to the Plummers Is- and, until now, has been the only catalog of the vas- land Herbarium. Of these, 13 collected 100 or more cular flora of the island and adjacent mainland to be specimens, six collected 300 or more, and only three published in the Club’s 100-year history. In 1953,

Fig. 5. North side of Plummers Island in winter, looking southwest across Channel from Mainland through ﬂoodplain forest to High (Cabin) Knoll. Photo by W. J. Kress.

Killip and Blake published what proved to be the island. This project also includes a pilot study of the only supplement to their checklist—‘‘Flowering feasibility of DNA barcoding in flowering plants Plants and Ferns—Supplement 1’’ (No. X in Natural (Kress et al. 2005). All of these collections have been History series). deposited in the Plummers Island Herbarium. Collecting has gone in cycles through the years. There is a problem with the date of collection giv- Extensive collecting was done in the early years of en, 9 May 1961, on the labels of 149 of the speci- Club ownership and especially in the 1930s before mens of Hotchkiss and Leonard. Many of these and after the Killip and Blake checklist appeared. In plants clearly could not have been collected so early the more than 50 years since their supplement was in the growing season; they were far too advanced in published there have been four major cycles. Hotch- their development. There is no apparent reason, how- kiss and Leonard made many collections in 1960– ever, to suspect other data on these labels. 1961, and in 1982–1986 Beyersdorfer systematically Since being moved to the Smithsonian Institution, collected the non-graminoid flora on behalf of Shetler the Plummers Island Herbarium, a collection now in anticipation of this present study. In 1997–1998, numbering over 3500 specimens, has always been Wells and her students, Rebecca L. Brown and Ven- kept separate from the general collection of the U.S. kat S. Murthy, did extensive documentary collecting National Herbarium (US) in the National Museum of in their study of changes in the floodplain vegetation Natural History. It is maintained as a separate part of of the island. In a new (2003–2005) cycle of col- the Herbarium of the Washington-Baltimore Area lecting and sight-recording, Shetler, Orli, Wells, W. (‘‘District of Columbia’’ or ‘‘DC’’ Herbarium). The John Kress, and others have attempted to establish Plummers Island Herbarium, as also the entire DC the present flora. Kress and coworkers have also been Herbarium, can be searched and consulted on-line documenting their feasibility study (‘‘An Electronic through the web site of the Flora of the Washington- Field Guide: Plant Exploration and Discovery in the Baltimore Area (persoon.si.edu/dcflora) by using 21st Century’’), begun in 2004 and focused on the ‘‘Plummers Island’’ as the ‘‘Locality.’’

Fig. 6. Cabin built by WBFC in 1901 on top of High Knoll, highest point of Island. Now amid oak-hickory-sugar maple upland forest. Photo by W. J. Kress.

The nonvascular plants, as traditionally circum- was the wife of Charles D. Walcott, fourth Secretary scribed, have been the subject of a number of papers. (1907–1925) of the Smithsonian Institution. She In the ‘‘Natural History of Plummers Island’’ series gained fame for her 400 watercolors of North Amer- are lists of Mosses by Leonard (1935), Fungi by Ste- ican wild flowers, sumptuously published by the venson and Ermold (1936), Hepaticae by Leonard Smithsonian in five volumes (Walcott 1925). Other and Pierce (1939), Lichens by Leonard and Killip notable early visitors to the island included Louis Ag- (1939), and Blue-green Algae (Myxophyceae) by assiz Fuertes and Theodore Roosevelt (McKenny & Drouet (1954). These lists are now very dated and Ricker 1937). have not been followed up by further surveys. More recently, however, Hale (1970, 1972, 1979) and La- Changing Vegetation Cover and Flora wrey and Hale (1977, 1981) published on lichen growth and stress from automobile pollution on The topographic relief, with mudflats, floodplain, Plummers Island. They studied the lichens on Cactus and various slopes and rocky outcrops, has afforded Rock (Figs. 8, 9) and showed that after the American a variety of habitats on the island despite its small Legion Bridge was built for the Capital Beltway (I- size. Over the years, repeated high water and flooding 495) automobile emissions stressed the lichens and on the lower parts have brought repeated cycles of reduced their growth. Comparable studies have not scouring and deposition and in the process periodic been done to examine the effect, if any, of air pol- renewal of the mudflat and floodplain flora (Figs. 10, lution on the vascular plants of the island. 11). The floodplain is quite sandy in places, espe- As an interesting botanical sidelight of the cially toward the east (downstream) end. At one time WBFC’s early years on the island, McAtee recorded it included a small pond at the west end and a small in miscellaneous notes (McAtee file, WBFC ar- marsh below Cabin Knoll (Erwin 1981). A small chives) that in June 1918 the Club granted Mary marshy area still exists on the northwest corner of Vaux Walcott use of the island for six months for her the island. sketching of wild flowers. Presumably, ‘‘use’’ meant The constant changes of the floodplain habitats no right of access, but this is not clear. Mary Walcott doubt account in significant measure for the relatively

Fig. 7. Important early botanists who collected and studied the Plummers Island ﬂora. Top, left to right, Sydney F. Blake (1892– 1959), Albert S. Hitchcock (1865–1935), Neil Hotchkiss (1901–1994); bottom, left to right, Ellsworth P. Killip (1890–1968), Emery C. Leonard (1892–1968). Photos from Washington Biologists’ Field Club (WBFC) archives, courtesy of M. C. Perry.

large cumulative flora recorded for the island and for by him on the island that year. It had been collected many of the apparently transitory accidentals. Ac- there several times before, but his was the last col- cording to Maxon (1935), for instance, in the summer lection ever to be made on the island. At that time, of 1930 the water was unusually low, and Killip re- he reported, there were ‘‘numerous’’ plants in ‘‘sev- corded ‘‘numerous aquatic and shore plants.’’ In their eral colonies,’’ although only two or three were in 1953 supplement to the their earlier checklist, Killip flower. Just when it disappeared is not documented, and Blake noted that nearly two-thirds of the 128 but the species has long been gone from the island. species being added to the flora were collected in The Iresine is one of at least three species that l936 and 1937, ‘‘following the disastrous floods of were new to the flora of the whole District of Colum- those years.’’ Their commentary continues: bia area when first discovered on the island, the other two being Crepis pulchra, small-flowered hawksbill, ‘‘In the low-lying parts at the upper end of the Island and along and Verbascum phlomoides, clasping-leaved mullein. the channel many of the trees and shrubs and much of the top- The vegetation cover of the island has become less soil were swept away. Seeds brought in with deposits of silt open over the years. Today, the island is covered with and sand had an abundance of sunlight and air in which to germinate, and constant collecting by members of the Club led a relatively dense tree canopy (Figs. 12–14), but early to the discovery of a surprisingly large number of novelties.’’ photographs (Fig. 15) show an island that, although forested, must have been cut-over in the 1800s, be- Of the accidental floristic element that likely was cause, particularly on the uplands, tree cover was brought in by the river over the years, the most no- very thin when the Club acquired the island (Erwin table member is Iresine rhizomatosa Standl. (blood- 1981). Juniperus virginiana (eastern red-cedar), a leaf) of the amaranth family (Amaranthaceae). A successional pioneer of old fields and open dry land, southeastern plant of low wet woodlands, it was de- was a prominent tree on the highest parts, where it scribed as a species separate from I. celosioides L. was scattered. Most of the red-cedar trees are gone (ϭ I. diffusa Humb. & Bonpl. ex Willd.) by P. C. now and have been replaced by various deciduous Standley (1915) on the basis of specimens collected species, notably maples, hickories, and oaks.

Fig. 8. Cactus Rock, looking upriver (west) along the Potomac River where the American Legion Bridge now crosses from Maryland (right side) to Virginia (left side), 1908 or 1909. Photo by H. S. Barber, from WBFC archives.

The gradual closing of the canopy layer obviously WBFC archives). It enumerates 538 native (mostly) has changed the habitats and, accordingly, has been and naturalized species, as compared to the 300 or accompanied by changes in the understory and the so species that are extant today. A surprising number ground flora. This succession has given rise to a rel- of the plants on that early list are among the 300 still atively diverse cumulative flora over the last century. there, over a hundred years later. Of the species on As for the flora extant at any one time, however, the the early list that no longer are present, many are trend clearly has been toward a reduction in diversity typical of open country. In some cases, alien species on the island, given the ever denser canopy. The have out-competed their native counterparts over the same can be said for the trend on the mainland, as years. For example, the early list includes the native the open, cultivated parts, with all their possibilities Celastrus scandens, American bittersweet, and the for accidental introductions, have returned to closed native Humulus lupulus, common hop, but today they forest (see below). appear to have been replaced entirely by the aliens The loss of open habitat and consequent reduction Celastrus orbiculatus, oriental bittersweet, and Hu- in diversity are apparent when the present Checklist mulus japonicus, Japanese hop, neither of which is is compared with the earliest known list of the vas- mentioned in McAtee’s list. cular plants, McAtee’s unpublished ‘‘Spermatophyta His list includes about 40 species (exact number of Plummer’s Island, Maryland,’’ dated 10 August depends on nomenclatural interpretations) that lack 1912, which was mentioned earlier (McAtee file, voucher specimens and were never verified and in-

Fig. 9. Opuntia humifusa (Raf.) Raf. (eastern prickly-pear) colony on Cactus Rock, 1908 or 1909. Photo by H. S. Barber, from WBFC archives.

cluded by Killip and Blake (1935, 1953), hence they areas. They may have been so transient that they are not included in our Checklist. The card file, surely were long gone without verifiable documentation by known and available to them, was probably a com- the time Killip and Blake put together their list pilation of field-identified species, and some of the (1935). Also, it is not always clear whether McAtee species in the list are questionable in light of what is was including some species from across the river in known today about the region’s flora. Many of the Virginia or other nearby locales. 40 or so species are weedy in nature and typical of The Opuntia humifusa (eastern prickly-pear) is one fields, meadows, openings and edges, or disturbed of perhaps many species that have disappeared from

Fig. 10. East end of Island with large sign identifying Island and brieﬂy explaining long-term studies by WBFC. Facing south toward river and Virginia shore. Photo by E. Lohnes.

the island in the last hundred years in all likelihood public through the years, especially after becoming because of the closing canopy, although other factors part of the C&O Canal National Historical Park. such as human disturbance and predation and even When the land was purchased, the mainland par- air pollution may have contributed to their disap- cel, with its three or four small woodland pools, pearance. Specimens and photographs preserved in swampy area, and cleared plots, added significantly the Plummers Island Herbarium show that a large to the habitat and species diversity of the island. To- colony of this cactus flourished in the early 1900s on day, the open areas are gone, and the property in the large boulder that became known as Cactus Rock general is heavily wooded. The pools, now in the (Figs. 8, 9), which is just downslope from the crest middle of relatively mature forest, may be little more of the high knoll. Curiously, the cactus is not in than wet areas in summer. McAtee’s list of the spring flora on the island in The mainland property had long been subjected to 1912, perhaps because it was not yet in flower when disturbance before purchase, which was continued the list was made (McAtee file, WBFC archives). The for a time by the Club. Over a third of the property, last collection was made in 1915, and the cactus was more or less surrounding the Lock House exclosure still present in the mid-1930s. There are no records at Lock 11, was open land that had been in agricul- to show how long the cactus persisted. Several per- tural use, perhaps in connection with the Lock House. sons recall seeing remnant plants in the 1960s and Club members did a little gardening there during war even as recently as the early 1980s, but there are no years, and at times the Club leased it to residents of supporting specimens or other records. Such a con- the Lock House for agricultural purposes (WBFC spicuous species would hardly have been overlooked web site, www.pwrc.usgs.gov/resshow/perry/bios/ or ignored by collectors in the 1960s and later. Cactus WBFCHome.htm, Biological Studies). Eventually, Rock, when it was much more exposed, was a prom- the cultivated areas of the mainland were left to re- inent, accessible high vantage point to which hikers vert to forest, and the vegetation cover has gradually were easily attracted. Thus, in addition to increasing become more homogeneous. Although the Lock shade, trampling likely took a toll and maybe col- House has not been occupied for many years, the lecting for gardens, as well. Certainly, foot traffic in- NPS still keeps open the small grassy clearing around creased as the island became more accessible to the it. The elimination of cultivation in time largely elim-

Fig. 11. A spring ﬂood of 2005 submerging east end of Island and nearly covering sign in Fig. 10. Photo by N. Bourg.

inated the open and edge habitats and with them the quently, from several times a year to once every 2–3 potential for accidental introductions through agri- years (Figs. 10, 11). They are dominated by a rich culture. Just how many, if any, of the species in the flora of species typically associated with floodplains, Checklist were introduced incidental to cultivation such as Platanus occidentalis (sycamore), Acer sac- and have since disappeared is unknown. charinum (silver maple), A. rubrum (red maple), A. Finally, in recent years heavy and ever increasing negundo (boxelder), Fraxinus pennsylvanica (green browsing by white-tailed deer on both the island and ash), Ulmus rubra (slippery elm), Juglans nigra the mainland are having a growing impact on the (black walnut), Lindera benzoin (spicebush), and vegetation, such that more and more herbaceous spe- many other species tolerant of flooding. Sycamore, cies (e.g., Impatiens capensis, orange jewelweed) are green ash, boxelder, and slippery elm form a closed unable to mature and produce seeds and may even- canopy throughout the island’s floodplain, and Asi- tually die out. In fact, it is likely that some species mina triloba (pawpaw) is conspicuous in the riparian have already been extirpated by the deer, but this is sub-canopy over much of the island. Parthenocissus difficult to determine. quinquefolia (Virginia-creeper), Vitis aestivalis (summer grape), V. vulpina (winter grape), and Toxico- Present Plant Communities dendron radicans (poison-ivy) are common vines This section is a general account of the plant com- throughout the island. A few non-native invasive spe- munities of Plummers Island by Wells, based on de- cies such as Alliaria petiolata (garlic-mustard) and tailed plot studies principally of the floodplain veg- Lonicera japonica (Japanese honeysuckle) are com- etation made by her on the island during the growing mon throughout most of the floodplain; Conium ma- season of 1997 with the assistance of Brown and culatum (poison-hemlock) and Celastrus orbiculatus Murthy. (oriental bittersweet) are conspicuous in some areas. Plummers Island’s varied topography supports The herbaceous vegetation of the riparian com- three main types of plant communities: riparian, ter- munities varies with habitat, soil depth, and flooding race, and upland forest. The riparian communities frequency. The floodplains on the lower end and at have relatively low topographic relief, occur at the the head of the island are relatively broad and gently lower elevations along the river, and are flooded fre- rolling. The deep sandy soil is redeposited by rapidly

Fig. 12. Upland forest in early spring on south slope of High Knoll, looking toward Virginia shore. Photo by N. Bourg.

Fig. 13. Understory vegetation in summer on terrace below High Knoll. Photo by W. J. Kress.

flowing water during floods, leaving bare sand which has developed nearby in a low area on the north side is quickly revegetated by opportunistic herbaceous of the island. plants. The lush herbaceous layer here is composed The river and lagoon banks of the island in most of Allium tricoccum (native ramp), Phlox divaricata areas are steep and sandy. The bank on the south side (wild blue phlox), Verbesina alternifolia (wingstem), receives full sun during the afternoon and bears an and V. occidentalis (southern flatseed-sunflower), and extremely dense assemblage of tall herbs such as the non-natives Artemisia annua (annual worm- Rudbeckia laciniata (tall coneflower), Ambrosia tri- wood), Polygonum cespitosum (Asiatic water-pep- fida (giant ragweed), wingstem, Hesperis matronalis per), Glechoma hederacea (ground-ivy), and Urtica (dame’s-rocket), and many others. The banks on the dioica (stinging nettle). north side are deeply shaded and sparsely vegetated A rocky channel in the floodplain, known as Upper as compared to the south-facing bank, bearing spe- Gap, on the northwest side of the smaller knoll has cies typical of the sandy floodplain. The species on shallow silty soil overlying tilted plates of bedrock the north bank include annual wormwood, Asiatic and supports a highly diverse flora. Trees include water-pepper, stinging nettle, wingstem, and southern Celtis occidentalis (hackberry), slippery elm, Salix flatseed-sunflower. nigra (black willow), Populus deltoides (cotton- Sandy and silty bars in a few locations around the wood), Betula nigra (river birch), boxelder, pawpaw, shore of the island remain submerged until the river and other floodplain species. Herbs include many na- level falls in late summer and exposes them, at least tive species such as Aster spp. (asters) and Solidago during dry years. These bars support a rich but short- spp. (goldenrods), Scrophularia marilandica (Mary- lived assemblage of herbaceous and woody species. land figwort), and Teucrium canadense (American The herbaceous species are extremely diverse and in- germander), and the non-natives Lonicera maackii clude Ammannia coccinea (tooth-cup), A. latifolia (Maack’s or Amur honeysuckle) and Lysimachia (Koehne’s ammania), Amaranthus spinosus (spiny nummularia (moneywort), as well as many of the amaranth), Sicyos angulatus (bur-cucumber), Pentho- species common in the deep sandy floodplain on the rum sedoides (ditch stonecrop), Mollugo verticillata island. Saururus cernuus (Lizard’s-tail) thrives in a (carpetweed), Lindernia dubia (false pimpernel), Mi- shallow pool between rock outcrops. A small pond mulus alatus (winged monkey-flower), Paspalum re-

Fig. 14. Potomac River, looking downriver (east) from south side of Plummers Island. Virginia shore is on right (south) side of river. Photo by E. Lohnes.

pens (water paspalum), and others, in addition to for soil profile development between fast-moving many found on the floodplain of the island. floods. Their topographic relief varies from almost The woody species on these bars are all first-year level to gently rolling. They are dominated by species seedlings of trees, such as river birch, Catalpa big- typically associated with moist upland sites, such as nonioides (southern catalpa), cottonwood, green ash, Acer saccharum (sugar maple) in the canopy, Sta- Paulownia tomentosa (empress-tree), sycamore, sil- phylea trifolia (bladdernut) in the tall shrub layer, and ver maple, and boxelder, that die when the bar is Asarum canadense (wild ginger), Matteuccia stru- flooded during the following winter. A small marsh thiopteris (ostrich fern), and Polystichum acrosti- persists near the south shore of the island in one lo- choides (Christmas fern) in the herb layer. cation, where Asclepias incarnata (swamp milk- The vegetation of terraces (Fig. 13) also contains weed), Lobelia cardinalis (cardinal-flower), Oron- many species common to floodplains, such as red tium aquaticum (golden-club), and Sagittaria latifolia maple, Liriodendron tulipifera (tulip-tree), hackber- (common arrowhead) are found in some years. Rock ry, pawpaw, and a few upland species such as Chion- outcrops that jut into the river at the west end provide anthus virginicus (fringe-tree) and Quercus rubra habitat for Hibiscus moscheutos (rose-mallow) and Cephalanthus occidentalis (buttonbush) as well as (northern red oak). One sloping terrace supports Dir- sycamore and willow. ca palustris (leatherwood), Tilia americana (bass- Terrace communities occur at the higher elevations wood), Cystopteris protrusa (lowland brittle fern), along the river and are flooded less frequently, having Caulophyllum thalictroides (blue cohosh), Cimicifu- a flood return interval greater than every 3 years, in ga racemosa (black cohosh), and Hydrophyllum vir- most cases as great as 25–30 years. Their soils are ginianum (Virginia waterleaf). On the island, terraces deep, sandy, mature with a developed soil profile, and offer the best display of showy spring ephemerals, rarely redeposited by flooding, in contrast with im- such as Mertensia virginica (Virginia bluebells), Di- mature riparian soils which typically have little time centra cucullaria (Dutchman’s-breeches), D. cana-

Fig. 15. Plummers Island, with cabin (Winnemana Lodge) on High Knoll, from Virginia shore in January 1905. Photo by A. A. Doolittle, from WBFC archives.

densis (squirrel-corn), Trillium sessile (sessile trilli- aster), Hieracium venosum (rattlesnake-weed), Soli- um), and Viola striata (creamy violet). dago caesia (blue-stem goldenrod), Carex nigromar- Upland forest communities occur on the two high ginata (black-edged sedge), Dichanthelium commu- knolls and among the large boulders and rock out- tatum (variable panic grass), and others, including crops of the island well above the river, and they many grasses and sedges. Vines such as Virginia- never flood (Fig. 12). Their soils are relatively thin, creeper, summer grape, winter grape, and poison-ivy clay-rich, with a developed soil profile, and are de- completely cover some of the cliffs and large boul- rived from the weathered granitic gneiss bedrock. ders, especially where they receive full afternoon sun Their topography ranges from rolling vegetated on the south side and on the high, massive rock slopes to very steep, barren, craggy cliffs and rock (‘‘Rock of Gibraltar’’) at the upper end of the island. outcrops. The cliffs on the north side of the higher Ailanthus altissima (tree-of-heaven) is established on knoll, known as Cabin Hill, are almost vertical, and the smaller knoll, and several trees have reached the their crevices and north-facing ledges provide habitat canopy. for basswood, sugar maple, Dryopteris marginalis (marginal shield fern), Christmas fern, and Polypo- Planted Species dium virginianum (rock polypody). Trees such as Quercus montana (chestnut oak), Two types of alien species make up the ‘‘intro- northern red oak, Q. alba (white oak), Carya glabra duced’’ flora of Plummers Island: (1) naturalized spe- (pignut hickory), Juniperus virginiana (eastern red- cies, i.e., species that are not native to the region and cedar), Ostrya virginiana (hop hornbeam), slippery have been introduced over the years by one means elm, U. americana (American elm), and red maple or another and become established in the region, in- form a somewhat open canopy over both knolls. cluding at Plummers Island (see Shetler & Orli 2000, Shrubs include Vaccinium stamineum (deerberry), V. 2002); (2) native species not present at Plummers Is- pallidum (lowbush blueberry), and others. The herb land that were deliberately brought in and planted on layer provides dense cover under the open canopy, the island, mainland, or both during the early years with species such as Aster divaricatus (white wood of the Club. Some, but not all, of these transplants

have always been treated as part of the flora of Plum- Aronia melanocarpa (Michx.) Elliott—black mers Island, and, for reasons explained later, a few chokeberry more of them are being added to our Checklist. *Aruncus dioicus (Walter) Fernald (as A. sylvester Though native in the region, they are regarded here Kostel.)—goat’s-beard as part of the introduced or, loosely speaking, natu- Betula lenta L.—black birch ralized flora of Plummers Island. Caltha palustris L.—marsh-marigold From the time it was obtained by the Club, the *Carya ovata (Mill.) K. Koch—shagbark hickory island was regarded as a preserve that would be al- *Catalpa bignonioides Walter—common catalpa lowed to return to nature more or less without inter- *Ceanothus americanus L. (formerly native ference. There were some exceptions to this, how- here)—New Jersey-tea ever. McKenny and Ricker (1937) wrote ‘‘No plant Clethra alnifolia L.—sweet-pepperbush or animal life may be destroyed, unless rarely for Comptonia peregrina (L.) J.M. Coult.—sweet-fern scientific studies, but Poison Ivy, Japanese honey- *Cornus alternifolia L.f.—alternate-leaved dog- suckle and the occasional Copperheads are except- wood ed.’’ In an early project, spearheaded by Albert K. Cypripedium acaule Aiton—pink lady’s-slipper Fisher, the Club initiated a regional arboretum (‘‘Ar- Dodecatheon meadia L.—shooting-star boretum Columbianum’’) on the mainland and began §Epigaea repens L.—trailing-arbutus to bring in some of the rarer native plants of the §Gaultheria procumbens L.—wintergreen region, particularly woody plants. This arboretum is *§Ilex opaca Aiton—American holly referred to on a number of specimen labels as the Iris cristata Aiton—dwarf crested iris ‘‘Fisher Garden’’ or ‘‘Fisher Farm.’’ McAtee (1930, Iris verna L.—dwarf iris p. 53) listed 35 species (below) that were planted on Liquidambar styraciflua L.—sweetgum the mainland. Lonicera sempervirens L.—trumpet honeysuckle A few of the 35 were also planted on the island, Lygodium palmatum (Bernh.) Sw.—American as a small ‘‘wildflower garden’’ (now gone without climbing fern a trace) around the fireplace chimney (McKenny & *Magnolia virginiana L.—swamp magnolia Ricker 1937) and perhaps elsewhere. McKenny and Mentha spicata L.—spearmint Ricker said the garden included a ‘‘colony of the rare Pellaea atropurpurea (L.) Link—purple cliffbrake Hart’s-tongue Fern’’ (Phyllitis scolopendrium (L.) §Pinus pungens Lamb.—table-mountain pine Newman). The garden may have been more of a con- Pinus taeda L.—Loblolly pine cept than a single place. The full list of species trans- Prunus virginiana L.—chokecherry planted to this garden or elsewhere on the island is Quercus macrocarpa Michx.—bur oak unknown, but apparently it included at least the six §Rhododendron maximum L.—rhododendron species in McAtee’s list marked here with the symbol Taxodium distichum (L.) Rich.—bald-cypress ‘‘§’’ plus Polypodium polypodioides (L.) Watt (res- §Tsuga canadensis (L.) Carrie`re—eastern hemlock urrection fern) and Pinus strobus L. (white pine). Ac- Veratrum viride Aiton—false hellebore cording to McKenny and Ricker, the Rhododendron Viburnum nudum L.—possum-haw maximum was planted on the north edge of the cliffs, Viola pedata L.—bird’s-foot violet and presumably all these species were planted on the *Vitis labrusca L.—fox grape rocky high knoll near the cabin, where the habitat was suitable, probably as an extension of the arbo- Killip and Blake, in their own list of transplants, retum (McAtee 1930, p. 53; Killip & Blake 1935; included two species, Hydrastis canadensis L. (gold- WBFC archives; WBFC web site, www.pwrc.usgs. enseal) and Spigelia marilandica L. (Indian-pink), gov/resshow/perry/bios/WBFCHome.htm, Biological that McAtee did not mention, but they did not specify Studies). A small note in the species card file labeled in their list which species were planted on the island ‘‘Island garden’’ lists by scientific or vernacular name and which on the mainland. the following 12 herbaceous taxa and a thirteenth in Thus, altogether, the published records show that unintelligible handwriting: Aquilegia, Chrysogonum, 39 species were transplanted to the island and/or Cypripedium, Dentaria, Erythronium, Jeffersonia, mainland during the early years of Club ownership ϩ Mertensia, Ornithogalum, Sanguinaria, Stellaria, (McAtee’s long list Hydrastis, Pinus strobus, Po- Trillium, and Viola striata. Apparently, they were in lypodium, Spigelia). At least 10 additional species are the wildflower garden. mentioned in fragmentary notes of McAtee (McAtee In their checklist of the flora Killip and Blake in- file, WBFC archives), but they were never docu- cluded without explanation nine of McAtee’s list of mented in print by him or others. Of the 10, none 35 planted species (marked with an asterisk ‘‘*’’). was included in the flora by Killip and Blake, and none has survived to recent times. *Aralia spinosa L.—Hercules’-club Of the 36 planted species named in print by

McAtee (list of 35 ϩ Polypodium), Killip and Blake’s one C. cordiformis (Wangenh.) K. Koch (P. C. (1935) own list of planted species included only 18. Standley 11481. 9 May 1915), the other C. gla- They did not include any of these 18 in their formal bra (Mill.) Sweet (E. P. Killip 13207. 24 Jun catalog of the flora, but they did include nine (see 1928). above) of McAtee’s other 18 species. Our Checklist Celtis mississippiensis Bosc (ϭ C. laevigata also includes these nine and another four from Willd.)—Based on misidentified specimen (A. S. McAtee’s list (see Flora Statistics). Hitchcock 12782. 13 Jun 1915) of C. tenuifolia From the wildflower garden, only the holly has Nutt. survived to the present, although no longer on the Ceratophyllum demersum L.—Based on misiden- high knoll, where it persisted until at least the early tified specimens of C. echinatum A. Gray. 1960s, as did also the hemlock (see species entries Cornus stolonifera Michx. (ϭ sericea L.)—Based in Checklist). One small but relatively old, staminate, on misidentified specimen (A. S. Hitchcock holly tree (DBH 12–15 cm) is growing in the de- 12915. 24 Jun 1917) of C. amomum Mill. from pression between the knolls. It is unclear from the the Island. record whether American holly also occurred natu- Cyperus dipsaciformis Fernald (ϭ C. retrofractus rally on the island at the time of the planting. Of the (L.) Torr.)—Based on misidentified specimen (S. wildflower-garden species planted on the mainland as F. Blake s.n. 5 Aug 1933) of C. lancastriensis well as the island (McAtee 1930, p. 54), only the Porter ex A. Gray. holly remains on the mainland today, represented by C. filiculmis Vahl—Based on misidentified speci- several shrubs and small trees that presumably are men (E. P. Killip 32633. 17 Aug 1938) of C. descendants of the original planting. lupulinus (Spreng.) Marcks. At some point long after these early introductions, Cystopteris fragilis (L.) Bernh.—In the strict Buxus sempervirens L. was planted on the Barton sense, no longer regarded as occurring in the Property (mainland), but Killip and Blake, despite Washington-Baltimore Area, where it is replaced Killip’s specimen (E. P. Killip 36989. 17 July 1949), by segregates C. protrusa (Weath.) Blasdell and did not include it in their 1953 list of additions to the C. tenuis (Michx.) Desv., both of which have flora. It also is not included here. Undoubtedly, Hed- been found on Plummers Island. era helix L. (English ivy), a longtime member of the Desmodium pauciflorum (Nutt.) DC—Based on flora, also was planted, although there is no record misidentified specimen (E. P. Killip 31069. 06 of the planting. It is well established at the Lock Aug 1933) of D. nudiflorum (L.) DC. (cf. Killip House for Lock 11 and other places on the mainland & Blake 1935, 1953). but only now is being included in the Checklist. Eragrostis hirsuta (Michx.) Nees—Based on mis- There are several other suspected deliberate intro- identified specimen (E. P. Killip & J. R. Swallen ductions, particularly among the naturalized species, 31889. 12 Jul 1936) of Eragrostis capillaris (L.) in the list of post-1953 additions (see Flora Statis- Nees. tics). Juncus dudleyi Wiegand—Based on two misiden- Excluded Species tified specimens (A. S. Hitchcock 13003. 15 July 1917; A. S. Hitchcock 15618. 29 Jul 1917) of J. As will be apparent from the synonymy, a number dichotomus Elliott. of the species recognized by Killip and Blake (1935, Petunia violacea Lindl.—Misapplied to P. axillar- 1953) are not recognized in our Checklist because is (Lam.) Britton, Sterns & Poggenb. or based they are now included in other species. In addition, on misidentified specimen (E. P. Killip 31928. the following species recognized by Killip and Blake 16 Aug 1936) of P. axillaris. are omitted from the Checklist for the reasons given Quercus coccinea Mu¨nchh.—Based on misidenti- below: fied specimen of Q. rubra L. (C. L. Pollard & Apocynum medium Greene—Specimens subse- P. Dowell 18. 16 Aug 1903), which was first quently redetermined as A. pubescens R. Br., identified as Q. palustris Mu¨nchh. and then as which has since been reduced to a variety of A. Q. coccinea. cannabinum L. Q. heterophylla (ϭϫheterophylla) F. Michaux— Carex complanata Torr. & Hook.—Based on mis- Q. phellos L. ϫ rubra L., included in phellos. identified specimens of C. hirsutella Mack. Q. saulii (ϭϫsaulei) C. K. Schneid.—Q. alba L. C. cristatella Britton—Based on misidentified col- ϫ montana Willd. (G. B. Sudworth s.n. 8 Jul lection (E. P. Killip 32608. 19 June 1938. 3 1906), included in alba. sheets) of C. tribuloides Wahlenb. Q. velutina Lam.—Based on misidentified speci- Carya alba (L.) K. Koch (ϭ C. tomentosa (Poiret) men (A. S. Hitchcock 12436. 25 Apr 1915) of Nutt.)—Based on two misidentified specimens, Q. rubra L.

Rosa virginiana Mill.—Based on several misiden- in the flora. Of the four, only the Taxodium was out- tified specimens of Rosa carolina L. side (slightly north of) its native range here. At least Sanicula marilandica L.—Included in1935 check- two trees were still standing as snags in 2004. list of Killip and Blake (as Sanicula marylan- Among fragmentary notes of McAtee in the dica) obviously on the basis of A. S. Hitchcock WBFC archives are some spring field trip lists for 12552, collected May 9, 1915, and identified as several years around 1910. They include some spe- this species. P. C. Standley 11493, collected on cies that are not vouchered with specimens and were the same date and identified only to genus, ap- not included by Killip and Blake (1935, 1953), pre- pears to be a duplicate. Although Hitchcock’s sumably for lack of confirming documentation. Ac- specimen was later (1933) annotated by Mildred cordingly, they are not included here. There is also E. Mathias as S. canadensis L., and Standley’s McAtee’s 1910 list of 534 spermatophytes, discussed specimen was annotated by Ren Hwa Shan and earlier, which includes 40 or so species that appar- Lincoln Constance in ‘‘1948–1949’’ as S. mar- ently were not included by Killip and Blake (1935, ilandica L., both specimens, which are in an ear- 1953) because they were rejected for one reason or ly flowering stage, appear to be closer to S. gre- another, and, therefore, we also have not included garia Bickn. It is clear from the disagreements them in our Checklist. Nevertheless, the fact remains of the experts that the sanicles of Plummers Is- that among the 75 or so species not included in our land are in need of careful study through the Checklist because Killip and Blake had passed over seasons. them there are quite a few credible records, which Scirpus validus Vahl (ϭ Schoenoplectus validus suggests that the cumulative flora of Plummers Is- (Vahl) A. Lo¨ve & D. Lo¨ve)—Mistakenly based land, including the mainland, since the WBFC began on an unidentifiable fragment of Juncus (E. P. studies there actually should total well over 900 spe- Killip 31986. 11 Oct 1936). cies. The boundaries of the mainland with respect to the Flora Statistics and Analysis canal and towpath on the outside and the island and river channel on the inside were never clearly defined Total Species 885 for floristic purposes (Figs. 1, 3, 4). Although Club Native Species 703 (79%) property ended at the towpath on the outer edge, a Introduced Species 182 (21%) number of species that grew in the adjacent portions Island Only or Island & Mainland of the canal were included by Killip and Blake in 809 (91%) their lists. For this reason, the canal between Locks Mainland Only 76 (9%) 10 and 12 is considered part of the mainland in our Ferns & Fern Allies 20 (2%) Checklist. As for the inner boundary, it is impossible Gymnosperms 6 (Ͻ1%) to determine whether the early collectors consistently Dicots 621 (70%) regarded plants on the rocky islets and among the Monocots 238 (27%) crossing rocks in the channel as belonging to the island flora or the mainland flora. The Checklist, like the combined lists of Killip and For our purposes, the middle of the channel is re- Blake (1935, 1953), includes all the native and nat- garded as the dividing line. In fact, where this bound- uralized ferns, fern allies, gymnosperms, and flow- ary is placed ultimately affects few if any species in ering plants that have ever been reported growing in terms of the island/mainland distinction. For exam- the wild on Plummers Island and/or the adjacent ple, the most recent collection of Paspalum repens P. mainland. In addition, as already indicated, the J. Bergius, cited in the Checklist, was made by She- Checklist includes a few species that were planted tler and Orli (2004-24) on an islet in the channel. and became naturalized or persisted for a long time, Because the islet site is nearer the shore of the island hence were noticeable elements of the flora for years than of the mainland, the collection is treated in the (see Planted Species). The status of each is made Checklist as from the island. In the past, however, it clear in its Checklist entry. had already been collected on both the island and the All but four were already included by Killip and mainland. Blake. The four transplanted species that have been The combined lists of Killip and Blake totaled 846 added here are Pinus taeda (loblolly pine), Taxodium species (see Killip & Blake 1953), compared to our distichum (bald-cypress), Tsuga canadensis (eastern 885. However, because of corrected identifications hemlock), and Viburnum nudum (swamp-haw). None and other taxonomic changes (e.g., combined spp., as of the four is still living, nor is the year each died Viola papilionacea in V. sororia), their lists would known, but all clearly persisted for years. Killip or total only about 800 in today’s taxonomy. In fact, of other early collectors preserved specimens of them, our 885 species, 92, distributed in 44 families, are indicating that the four were being treated as species new to the cumulative known flora of Plummers Is-

land, including the mainland. These are flagged in HEDERA HELIX—I the Checklist with a plus sign (ϩ) HIBISCUS TRIONUM—M Only 42 of the 92 species were discovered in or LAPSANA COMMUNIS after 1953. The other 50 were collected in earlier LIGUSTRUM OBTUSIFOLIUM—I years and, for whatever reason (misidentified, buried LONICERA MAACKII—I in unprocessed specimens, etc.), went unrecognized LUDWIGIA PEPLOIDES—W and were not included by Killip and Blake in either Myosotis verna of their lists. Thus, although they were never reported MYRIOPHYLLUM SPICATUM before, they are not species newly found since the POLYGONUM CUSPIDATUM—I last summary was published in 1953. Of the 42 spe- P. hydropiperoides—I cies dating to 1953 or later, 23, about 50%, are in- P. PERFOLIATUM—M troduced. This clearly reflects the explosive spread in ROSA MULTIFLORA—I recent years of alien species in the local flora. Rubus hispidus The 42 new species dating to l953 or later are the SOLANUM PHYSALIFOLIUM—M following, listed alphabetically within category. This SONCHUS ASPER—I represents almost one new species a year, no doubt STYLOPHORUM DIPHYLLUM—I counter-balanced by an equal or greater loss per year. Valerianella radiata—W Codes indicate if the species were collected or sight- Viburnum rafinesqueanum ed in 1997 by Wells and her students or have been seen more recently by Wells or other botanists. Add- Monocots ing up the species coded I or M, it can be seen that 26 of the 42 species (62%) were present as recently ARTHRAXON HISPIDUS—W as 2000 (Carex albolutescens) or 2003–2004. By Carex aggregata—I contrast, only 5 species (Aster lateriflorus, Solidago C. albolutescens—M (2000) rupestris, Carex planispicata, Celtis tenuifolia, Cys- C. gracilescens—I topteris protrusa, as C. fragilis) of the 50 pre-1953 Echinochloa muricata additions (10%) to the Checklist were still present Elymus macgregorii—I this recently. We have no ready explanation other E. riparius—I than chance for why 90% of these have disappeared Lemna minor in contrast to about 65% for the flora as a whole (see L. obscura below). MICROSTEGIUM VIMINEUM—I Orontium aquaticum—W Key 31 dicots, 11 monocots; 19 native species, 23 CAPS AND SMALL CAPS—Naturalized species (55%) naturalized species No code—not seen recently Clearly, many of the species in the Checklist are I—Seen on island only or island and mainland in no longer present in the Plummers Island flora. The 2003 or 2004 flora is in constant flux from season to season and M—Seen on mainland only in 2003 or 2004 ex- year to year, especially because of frequent flooding. cept as otherwise indicated Many of the species found over the years on the ac- W—Collected or seen on island by E. F. Wells and tive floodplain have been very transient, lasting a sea- students in 1997 son or two and then disappearing. In past especially dry years, when wide mudflats have been exposed Dicots during much of the summer, new species have shown ALBIZIA JULIBRISSIN—I up for at least that season. Thus, at any given time Ammannia coccinea—W the total catalog of extant species is impossible to Amorpha fruticosa determine precisely. AMPELOPSIS BREVIPEDUNCULATA—M Some species apparently have come and gone ARTEMISIA VULGARIS—I more than once. Astragalus canadensis (Canada Asclepias quadrifolia milk-vetch), for instance, was collected (as A. caro- BERBERIS THUNBERGII—M linianus) in 1903 by T. H. Kearney, but by 1935 Kil- CELASTRUS ORBICULATUS—I lip and Blake, who had not seen this or any other CONIUM MACULATUM—I specimen but included the species on the basis of a Conopholis americana reliable report, speculated that the species was ‘‘ex- EUONYMUS ALATUS—M tinct’’ on the island. In 1940, however, Killip (32928) E. FORTUNEI—M collected it again. In their 1953 supplement Killip Eupatorium serotinum—I and Blake said it had persisted ever since, but in the

years since 1953 the species has disappeared from cumulative total. It seems unlikely, given the ecolog- the flora again. ical succession that has continued to take place over The likelihood of a given species in the Checklist the many years and the steadily increasing browsing still being present in the flora can be judged to some of white-tailed deer in recent years, that any more extent by how recently it was collected or otherwise than another 50 species at best can be found at pre- documented. For this reason, the latest collection or sent, for a total of around 350 extant species. This is observation is cited for each species in the Checklist. surely a very liberal estimate. Although the most recent collections are still being The total number of 885 is almost a third (32%) processed, insofar as possible they have been cited of the 2794 species of vascular plants recently re- in the Checklist where appropriate. (For the most up- ported for the entire Washington-Baltimore Area to-date listings of specimens on deposit, search the (Shetler & Orli 2000, 2002). Nearly 36% of the flora DC Herbarium database (locality: Plummers Island) of the Washington-Baltimore Area is composed of on the Web site (persoon.si.edu/dcflora) of the Flora introduced species, almost twice the 21% of the of the Washington-Baltimore Area.) The Kress col- Plummers Island flora. The comparison may be mis- lections and the recent collections and observations leading, however, because the figures are based on of others form the basis for flagging each species in cumulative species lists, not on present floras. For the Checklist that has been seen on the island and/or Plummers Island, for which current figures are avail- mainland in 2003–2005 (see Key). able, the percentages are still the same, based on the 300 species counted in 2003–2005. Of them, 62 or ϩ Total species seen in 2003–2005 (I M) 300 21% are introduced. As shown above, however, of Native species 238 (79%) the 42 species added to the flora since 1953, 55% are Introduced species 62 (21%) introduced. A contemporary comparison with the Island ϩ island & mainland (I) whole Washington-Baltimore Area cannot be made 250 (83%) because the size of its extant flora at this point in Mainland only (M) 50 (17%) time is unknown.

Of the 885 species recorded historically for either Acknowledgments the island, the mainland, or both, the current 300 represents about 34%. If the ‘‘mainland only’’ species We are indebted to many persons for help and sup- are excluded, then the total is 809, of which the cur- port in preparing this Checklist. Early in the project rent 250 represents about 31%. Thus, the present flo- Susan K. Wiser, a former assistant of Shetler, col- ra of Plummers Island would appear to be about a lected 44 specimens and gathered some initial work- third of the cumulative flora, whether or not the ing materials. Several specialists have kindly exam- mainland-only species are included. ined specimens in their groups as indicated: L. J. Among the species that Wells and her students col- Davenport (Lemnaceae), Robert Haynes (Najada- lected or noted on the island in 1997, 80 were not ceae, Potamogetonaceae), David B. Lellinger (Cys- found here again in 2003–2005, although nine of topteris), Paul M. Peterson (various grasses), Robert them were found on the mainland, leaving 71 unac- (‘‘Rob’’) J. Soreng (various grasses), Mark Strong counted for in the present flora. In the Checklist, her (Carex), and Alan T. Whittemore (Quercus). Soreng, collections are cited, if not superseded, and her ob- Strong, and Whittemore have also participated in re- servation-only records are denoted at the end of the cent fieldwork. entries by a ‘‘W,’’ meaning last seen on the island in Rebecca L. Brown and Venkat S. Murthy assisted 1997, by Wells. (The nine that did show up in 2003– Wells in 1997 in making collections on Plummers 2005 but only on the mainland are denoted by ‘‘M, Island itself to document their study of the vegeta- W.’’) If one were to assume that all of the species tion, particularly on the floodplain. The first set (137 found as recently as 1997 are still on the island, specimens) of these important collections is depos- mainland, or both, and will turn up sooner or later, ited in the Plummers Island Herbarium of the U. S. then, adding to the 300 the 71 species not actually National Herbarium. seen again in 2003–2005, one could project an extant We could not have done this project without the flora of the island and mainland as high as 371 spe- continuing support of the Department of Botany, cies. This would represent 42% of the historical total chaired by W. John Kress. Kress, with the assistance of 885 for the island and mainland together or 46% of Michael Butts and Norman A. Bourg, made an of the historical total of 809 for the island alone. important new collection of about 150 specimens Thus, the extant flora of Plummers Island could during 2004, which were made available to us for number upwards of half of the historical total, but study and citation, thanks especially to Ida Lopez. this seems highly unlikely. It is much more likely that He also provided some of the photographs for this the present flora is closer to a third than a half of the paper, as did Bourg. We are indebted also to Matthew

C. Perry and Edward Lohnes for photographs. Dan H. Janzen. 2005. Use of DNA barcodes to identify flower- Nicolson, as always, was patient and generous with ing plants. Proceedings of the National Academy of Sci- ences 102: 8369–8374. his time and expertise whenever asked for help with Lawrey, J. D., and M. E. Hale, Jr. 1977. Studies on lichen growth nomenclatural problems. His review, as well as that rate at Plummers Island, Maryland. Natural History of of an anonymous reviewer, provided many helpful Plummers Island, Maryland XXIII. Proceedings of the Bi- suggestions for improving the manuscript. Katherine ological Society of Washington 90:698–725. Rankin and George (‘‘Rusty’’) F. Russell facilitated , and . 1981. Retrospective study of lichen lead ac- cumulation in the northeastern United States. The Bryolo- any number of specimen processing transactions, so gist 84: 449–456. that it has been possible to incorporate newly col- Leonard, E. C. 1935. Mosses. Natural History of Plummers Island lected specimens into the Plummers Island Herbari- III. Proceedings of the Biological Society of Washington um quickly. 48: 135–137. Finally, we are most grateful to the National Park , and E. P. Killip. 1939. Lichens. Natural History of Plum- Service and particularly the authorities of the C&O mers Island, Maryland VIII. Proceedings of the Biological Society of Washington 52: 23–26. Canal National Historical Park for making our field- , and M. E. Pierce. 1939. Hepaticae. Natural History of work efforts possible by continuing to issue the nec- Plummers Island, Maryland. Proceedings of the Biological essary collecting permits. We also gratefully ac- Society of Washington 52: 21–22. knowledge the financial support of the Washington Maxon, W. R. 1935. Introduction. Natural History of Plummers Biologists’ Field Club that makes the publication of Island, Maryland I. Proceedings of the Biological Society of Washington 48: 115–117. this paper possible. McAtee, W. L. 1930. Seventh supplement to the Flora of the Dis- trict of Columbia and Vicinity. Proceedings of the Biolog- Literature Cited ical Society of Washington 43: 21–54. McKenny, M., and P. L. Ricker. 1937. Winnemana—Beautiful Is- Chuang, T. I., and L. Constance. 1977. Cytogeography of Phacelia land. A Maryland Wildlife Sanctuary. Wildflower (1): 8– ranunculacea (Hydrophyllaceae). Rhodora 79: 115–122. 11. Drouet, F. 1954. Blue-green algae (Myxophyceae). Natural History Sewell, M. 2003. Biosystematics of the Phacelia ranunculacea of Plummers Island, Maryland XI. Proceedings of the Bi- complex (Hydrophyllaceae). MS Thesis. Miami University, ological Society of Washington 67:239–241. Oxford, OH. 60 p. Erwin, T. L. 1981. The ground beetles of a temperate forest site Shetler, S. G., and S. S. Orli. 2000. Annotated Checklist of the (Coleoptera: Carabidae): An analysis of fauna in relation to Vascular Plants of the Washington-Baltimore Area. Part I. size, habitat selection, vagility, seasonality, and extinction. Ferns, Fern Allies, Gymnosperms, and Dicotyledons. Natural History of Plummers Island, Maryland XXVI. Bul- Smithsonian Institution, Washington, DC. xv ϩ 188 p. (Du- letin of the Biological Society of Washington 5: 104-224. plicated) Gleason, H. A., and A. Cronquist. 1991. Manual of Vascular Plants . 2002. Annotated Checklist of the Vascular Plants of the of Northeastern United States and Adjacent Canada. New Washington-Baltimore Area. Part II. Monocotyledons. York Botanical Garden, NY. 910 p. Smithsonian Institution, Washington, DC. xiv ϩ 95 p. (Du- Hale, M. E., Jr. 1970. Single-lobe growth-patterns in the lichen plicated) Parmelia caperata. The Bryologist 73: 72–81. Standley, P. C. 1915. A new species of Iresine from the United . 1972. Infestation of the lichen Parmelia baltimorensis States. Proceedings of the Biological Society of Washington Gyel. & For. by Hypogastrura packardi Folsom (Collem- 28: 171–174. bola). Natural History of Plummers Island, Maryland XXI. Stevenson, J. A., and E. M. Ermold. 1936. Fungi. Natural History Proceedings of the Biological Society of Washington. 85: of Plummers Island, Maryland V. Proceedings of the Bio- 287–295. logical Society of Washington 49: 123–131. . 1979. Lichen growth responses to stress induced by au- Walcott, M. V. 1925. North American Wild Flowers. Smithsonian tomobile exhaust pollution. Science 204: 423–424. Institution, Washington, DC. 5 vols. (400 color pls.). Hermann, F. J. 1946. A Checklist of Plants in the Washington- Ward, L. F. 1881. Guide to the flora of Washington and vicinity. Baltimore Area. Ed. 2. Conference on District Flora, Smith- Bulletin of U.S. National Museum 22: 1–264. sonian Institution, Washington, DC. Duplicated. 114 p. Washington Biologists’ Field Club Archives. Currently (2005) Hitchcock, A. S., and P. C. Standley. 1919. Flora of the District housed in Department of Botany and maintained by chair- of Columbia and vicinity. Contributions from the U.S. Na- man of Archives Committee of WBFC, Laurence E. Skog, tional Herbarium 21: 1–329. curator of botany emeritus, National Museum of Natural Killip, E. P., and S. F. Blake. 1935. Flowering plants and ferns. History, Smithsonian Institution, Washington, DC. Natural History of Plummers Island, Maryland II. Proceed- ings of the Biological Society of Washington 48: 118–134. Web Sites , and . 1953. Flowering plants and ferns—Supple- ment. Natural History of Plummers Island, Maryland X. Flora of the Washington-Baltimore Area, 2005: http://persoon.si. Proceedings of the Biological Society of Washington 66: edu/dcflora 31–38. Washington Biologists’ Field Club (WBFC), 2005: http://www. Kress, W. J., K. J. Wurdack, E. A. Zimmer, L. A. Weigt, and D. pwrc.usgs.gov/resshow/perry/bios/WBFCHome.htm

CHECKLIST local sources. The type of synonymy is not always indicated, and, on the face of it, not all of the syno- The Checklist is a cumulative list of all the native nyms are legitimate synonyms. Some are legitimate or naturalized vascular plant species ever document- names for other species under which the Plummers ed for the Island and adjacent Mainland. A few trans- Island plants have been treated in the past, either by planted species, clearly indicated, are also included. mistake or owing to a broader species concept at the The Checklist is based primarily on the voucher spec- time. The purpose of the synonyms is not to give imens preserved in the Plummers Island Herbarium, nomenclatural history but to help the user of our which can be accessed online through the Web site Checklist to trace an accepted name to earlier local of the Flora of the Washington-Baltimore Area (see usage, which may have been in error. Thus, for two References Cited), and every specimen cited is in this fern examples, Polypodium virginianum was includ- herbarium or soon will be. The classification, circum- ed by Killip and Blake in a broad P. vulgare, and scription, and nomenclature of the species follow Cystopteris fragilis included the segregates C. pro- Shetler and Orli (2000, 2002), as well as the current trusa and C. tenuis. Consequently, P. vulgare and C. arrangement in the DC Herbarium, with two excep- fragilis are listed as synonyms of the respective spe- tions: Dentaria is placed in Cardamine here and He- cies, which, strictly speaking, they are not. In the case patica in Anemone. This, increasingly, is current of hybrids, as in Quercus, the hybrid name has been practice. Otherwise, the classification is largely con- listed as a synonym only under the parent species to servative and conventional for the practical reasons which the putative hybrid specimen has been re- discussed in Shetler and Orli (2000) and for the most ferred. part does not reflect the explosive continuing redefi- The specimen citations include, to the extent given nition of families and genera resulting from molec- on the collection label, the collector(s), collection no., ular studies and phylogenetic analyses. No attempt date of collection, and pertinent locality data. The has been made to treat infraspecific taxa in the flora. locality data are not necessarily verbatim, unless in The accepted genera and species in the list are not quotation marks, and may be condensed. Here and in italics, as is conventional for scientific names, but henceforth in the Checklist entries ‘‘Mainland’’ and in boldface Roman type to set them apart as the en- ‘‘Island’’ are treated as place names and capitalized. tries, not to be confused with the italicized synonyms (Otherwise, in the general narrative of the Introduc- and collector citations. tion they have not been capitalized.) For genera and/or species known or believed to be Unless otherwise indicated, the latest specimen naturalized aliens in the Washington-Baltimore Area, represents the most recent documented sighting of the as indicated by font in Shetler and Orli (2000, 2002), species. The lack of a recent specimen or other sight- the scientific names likewise are given in ‘‘caps and ing documentation, however, does not necessarily in- small caps’’ (FULL SIZED AND SMALLER CAPITAL LET- dicate that the species no longer occurs on the Island TERS) here. If the genus includes native and natural- or the Mainland, but in many cases this probably is ized species, then only the epithets of the alien spe- true. cies are in small caps, and the generic name is not At the end of an entry, the letter ‘‘I’’ means that in caps and small caps. A dagger (†) before the spe- the species has been observed on the Island and in cific name denotes a species found only on the Main- some cases also the Mainland, in 2003–2005; an land, and a plus (ϩ) denotes a species that is new to ‘‘M’’ means that the species has been observed only the flora, not included in either of the earlier lists of on the Mainland in 2003–2005; and a ‘‘W’’ means Killip and Blake. that the species was seen but not collected on the For each species entry, following in sequence after Island in 1997 by Wells, Brown, and Murthy during the scientific name are (1) one or more common their vegetation study (Mainland not included) but names, (2) pertinent scientific name synonyms, if has not been seen more recently. In the case of cited any, (3) the number of specimens, if any, in the specimens of Wells et al., the year 1997 is already in Plummers Island Herbarium, given in parenthesis, (4) the species entry, which, therefore, is not also marked citation of the most recent specimen on deposit at the with a ‘‘W.’’ Smithsonian, or, lacking a voucher specimen, citation of the source of information, and (5) ‘‘Comments.’’ Collecting Sites The Comments are all by Shetler but may include the quotation or citation of others. Also, anything in a Over the years, the different collectors have de- species entry that is in brackets represents an inser- veloped their own names for various sites on the Is- tion by Shetler. land and Mainland, which were not always the same The synonymy is tailored particularly to past usage for the same places. There is no existing gazetteer or for Plummers Island, either in the Plummers Island recorded documentation, such as a labeled map, for Herbarium or in the lists of Killip and Blake or other these site names. Some are obvious or traditional, and

the others have to speak for themselves from the con- East End—lower or downriver end of Island. (22) text of their associated label data. In any event, the Fern Valley—area with large colony of ostrich whole area is so small in geographic terms that local fern, Matteuccia struthiopteris, on alluvial ter- site names are likely to be of limited value to most race downslope on Cabin Hill, southeast of cab- potential users of this Checklist. Nevertheless, some in. (17) of the most frequently used site names are listed be- Ferry—tethered boat used from time to time to low with brief explanations of their locations or ap- transport WBFC members across channel to and parent locations. Major sites are labeled on the map from Island; area is near mid-point of Island of the Island and Mainland (Fig. 1). Others are keyed (north of cabin), but exact location not fixed and to the map by number, and the number is given in has moved back and forth along Channel over parentheses at the end of the entry. A few, as indi- the years, as flooding has changed shores. cated at the ends of the entries, are labeled on the Ferry Dock—a dock of sorts for ferry was built aerial photograph of the area (Fig. 2). Except in the and rebuilt after floods a number of times on obvious cases, the map locations should be viewed one or both sides of Channel, not always at same as approximations. spot. Effort to have permanent dock eventually abandoned for temporary measures as needed. Barrens (or ‘‘Barrens’’)—flood-swept, exposed (Location of dock moved back and forth with area of Island (and Mainland?) along river chan- ferry.) nel that separates Island from Mainland; largely Fisher Garden (or Farm)—western third of Main- grown up in secondary forest. (16) land area where A. K. Fisher started an arbo- Barton Property—1.4-hectare parcel between Rock retum for trees and shrubs native to region, es- Run and Lock 10 added to Mainland portion of pecially the rarer ones (see Planted Species). WBFC property in 1924. (6) Floodplain—low areas of Island subject to regular, Beltway—Capital Beltway, Interstate 495, which occasional, or rare flooding, depending on ele- crosses Potomac River just west (upriver) of Is- vation; consists of active muddy zone along riv- land and connects Maryland with Virginia via er and Channel banks and one or more higher, American Legion (Cabin John) Bridge. (Fig. 2) wooded terraces. Boat Landing—landing area on river side of Cabin Frog Pond (s)—chain of three or four small wood- Hill directly downhill (south) from cabin; not land ponds in western third of Mainland, now used for many years. (18) reduced to one or two, depending on rainfall. C&O Canal—Chesapeake and Ohio Canal, now (3) part of C&O Canal National Historical Park. Gap—saddle depression between Cabin Hill and Cabin—WBFC clubhouse built in 1901 mid-Island West knolls. (13) on highest point and still kept in repair and used; High Knoll—Cabin Hill, Cabin Knoll. (15) officially called Winnemana (‘‘beautiful is- I-495 bridge—see Beltway. (Fig. 2) land’’) Lodge in early years. Lagoon—see Channel. Cabin Hill (Knoll)—high knoll mid-Island on Locks 10–13—locks of old C&O Canal in vicinity which WBFC cabin stands. (15) of Plummers Island. Lock 10 marks eastern Cabin John Bridge (properly called American Le- boundary of Mainland of WBFCs original prop- gion Bridge; see Beltway). (Fig. 2) erty and has small canal parking area. Lock 11, Cactus Rock—flat-topped rock promontory just just west of Rock Run, is in northeast corner of southwest and downslope from cabin; overlooks original Stewart Farm parcel of Mainland. Lock Potomac River and once harbored a small pop- 12 marks western boundary of Mainland, and ulation of Opuntia humifusa, eastern prickly- Lock 13 is west of property. pear cactus. (14) (Figs. 8, 9) Lock House—lock keeper’s residence during years Channel (Lagoon)—narrow channel of Potomac of canal operation. Houses still present at Locks River that separates Island from Mainland. 10 and 11, but in use only at Lock 10. (5) Crossing Rocks (also Rock Crossing)—rocky nar- Lower end—east or downriver end of Island. (22) rows of channel near east end of Island where Mainland—original WBFC property between channel can be bridged on foot over rocks at C&O Canal, Locks 10–12, and Island (15.6 times of low water. hectares [38.5 acres]). Dead Run—a small tributary feeding into Channel Northwest Swamp—swampy woods in northwest near west end of original Mainland property. corner of Mainland property. (1) Not the well known Dead Run in Virginia across Outlook Rock—probably same as Rock of Gibral- river opposite Island. (2) tar. (10) East Sandbar—sandbar at east (downriver) end of Party spot—sheltered area among rocks near west Island. (20) end but just northeast of Rock of Gibraltar. (8)

Poachers Landing—boat landing somewhere end (northwest of lower knoll); once much more around the east end, apparently on river side of exposed. (7) Island. (21) West End—upper or upriver end of Island. (9) Prospect Rock—west end; probably same as Rock West Knoll—second highest point on Island. (12) of Gibraltar. (10) West Sandbar—river sandbar at west end. (11) Rock Crossing (see Crossing Rocks). Quick Key to Symbols and Abbreviations Rock of Gibraltar—major rock outcrop and promontory at west end. (10) CAPS AND SMALL CAPS—(1) Genus and species nat- Rock Run—small Potomac River tributary just uralized (e.g., ANTHEMIS ARVENSIS); (2) species east of Lock 11, forming original but not ulti- only (e.g., Bidens ARISTOSA). †—Species known only from Mainland. mate eastern boundary of Mainland property of ϩ—Species new to Checklist. WBFC. I—Species collected or seen in 2003–2005 on Is- Stewart Farm—large, once cultivated, eastern part land only or Island and Mainland. of Mainland, bounded on the east by Rock Run. M—Species collected or seen in 2003–2005 on (4) Mainland only. Sycamore Cove—little cove near east end on river W—Species seen but not collected in 1997 by side. (19) Wells et al.; her 1997 observations are so indi- Upper End—upriver (west) end of Island. (9) cated only if they have not been superseded by Upper Gap—depression/opening near northwest more recent collections or observations.

FERNS AND FERN ALLIES 7481, 20 May 2004. Ridge above central plain (SW of cabin). I. EQUISETACEAE (Horsetail Family) Polystichum acrostichoides (Michx.) Schott— Equisetum arvense L.—common horsetail, ﬁeld Christmas fern. (Aspidium acrostichoides horsetail. (4) M. Beyersdorfer 99, 8 May 1983. (Michx.) Sw.) (3) W.J. Kress & M. Butts 04- Mainland, sandy valley of Rock Run. 7516, 11 Jun 2004. Floodplain; mid-island near hyemale L.—common scouring-rush. (E. prealtum north shore. I. Raf.) (2) M. Beyersdorfer s.n., 1982 or 1983. Mainland, Dead Run area. OPHIOGLOSSACEAE (Adder’s-tongue Fern Family) SELAGINELLACEAE (Spikemoss Family) Botrychium †dissectum Spreng.—cut-leaved gra- Selaginella †apoda (L.) Spring—meadow spike- pefern, lace-frond grapefern, dissected grape- moss. (1) E.P. Killip 31148, 22 Apr 1934. Main- fern. (B. obliquum Muhl.) (4) E.P. Killip 32653, land, near old spring. 11 Jun 1939. Mainland, just inside fence about 100 feet east of upper gate. ADIANTACEAE (Maidenhair Fern Family) virginianum (L.) Sw.—rattlesnake fern, common Adiantum pedatum L.—northern maidenhair fern. grapefern. (3, including photograph) M. Beyers- (1) E.P. Killip 31283, 19 Aug 1934. West Knoll. dorfer s.n., 2 Sep 1984 [photograph]. Mainland, edge of C&O towpath midway between Locks ASPLENIACEAE (Spleenwort Family) 11 and 12. Asplenium ϫebenoides R.R. Scott (A. platyneuron POLYPODIACEAE (Polypody Fern Family) ϫ rhizophyllum)—Scott’s spleenwort. (1) W. Palmer s.n., 23 Apr 1899. In a rock crevice. Polypodium virginianum L.—rock polypody, com- platyneuron (L.) Britton, Sterns & Poggenb.—eb- mon polypody. (Polypodium vulgare L.) (5) M. ony spleenwort. (7) W.J. Kress & M. Butts 04- Beyersdorfer 1, 4 Apr 1982. Cabin Hill, out- 7488, 20 May 2004. Ridge above central plain, cropping behind cabin. I. mid-island. I. rhizophyllum L.—walking fern. (Camptosorus rhizophyllus (L.) Link). (5) E.C. Leonard & N. WOODSIACEAE (Cliff Fern Family) Hotchkiss 3207, 23 Jul 1960. Just off trail to east Cystopteris ϩprotrusa (Weath.) Blasdell—lowland about midway between base of rocky Cabin Hill brittle fern, southern bladder fern. (C. fragilis and summit. Comments: Ferry-Cabin trail, ver- (L.) Bernh.) (5) W.J. Kress & M. Butts 04-7484, tical rock surface. trichomanes L.—maidenhair spleenwort. (1) J.E. 20 May 2004. Central plain (SW). Comments: Benedict Jr. 2926, 19 Aug 1934. Twelve paces The dominant segregate of C. fragilis s.l. on the south of cabin, on rocks. Island. I. ϩtenuis (Michx.) Desv.—Mackay’s brittle fern, AZOLLACEAE (Mosquito Fern Family) upland brittle fern. (C. fragilis (L.) Bernh.) (2) W.R. Maxon 6495, 1 Aug 1920. Rich alluvial Azolla caroliniana Willd.—eastern mosquito fern. sandy loam [2 sheets]. Comments: Segregate of (1) E.C. Leonard & N. Hotchkiss 3591, 9 May C. fragilis s.l. 1961. Channel above ferry, on mud and surface Matteuccia struthiopteris (L.) Tod.—ostrich fern. of water. (Pteretis nodulosa (Michx.) Nieuwl., P. pensylvanica (Willd.) Fernald). (4) M. Beyersdorfer DENNSTAEDTIACEAE (Bracken Fern Family) 223, 5 Sep 1982. Fern Valley, south of Cabin Hill. I. Dennstaedtia punctiloba (Michx.) T. Moore—hay- Onoclea sensibilis L.—sensitive fern. (5) M. Beyers- scented fern. (1) E.P. Killip & J.E. Benedict dorfer 68, 21 May 1983. Mainland, C&O Ca- 31287, 19 Aug 1934. South slope of Cabin nal. I. Hill. M. Woodsia obtusa (Spreng.) Torr.—blunt-lobed cliff fern. (4) E.C. Leonard & N. Hotchkiss 3323, 27 DRYOPTERIDACEAE (Wood Fern Family) Sep 1960. Upper Gap, West End, rock crevice. Dryopteris marginalis (L.) A. Gray—marginal Comments: Observed in 2004 by Shetler and shield fern, marginal wood fern. (Aspidium mar- Orli in crevices of sandstone blocks in walls of ginalis (L.) Sw.) (11) W.J. Kress & M. Butts 04- Lock 12, just north of Mainland boundary. I.

GYMNOSPERMS Butts 04-7504, 8 Jun 2004. Mid-island, north CUPRESSACEAE (Cypress Family) shore, along river [channel]. I. rubrum L.—red maple. (1) Collector Unknown Juniperus virginiana L.—eastern red-cedar, Virgin- s.n., 15 May 1926. West end of Island. I. ia juniper. (4) W.J. Kress & M. Butts 04-7480, saccharinum L.—silver maple. (6) W.J. Kress & 20 May 2004. Just north of Cactus Rock. I. M. Butts 04-7503, 20 May 2004. Mid-island, Taxodium ϩ†distichum (L.) Rich.—bald-cypress. north shore, along river [channel]. I. (1) E.P. Killip 36575, 17 May 1942. Mainland, saccharum Marshall s.l.—sugar maple. (A. bar- eastern end of east Frog Pond. Comments: batum Michx., A. leucoderme Small., A. nigrum Planted by A.K. Fisher. Still persisting in 1982, F. Michx.) (14) W.J. Kress & M. Butts 04-7531, according to M. Beyersdorfer, but dead by Dec. 23 Jun 2004. Below Cactus Rock (W side). I. 2002 (George E. Watson) or well before (prob- Comments: Specimens of sugar maple have ably). been misidentiﬁed as A. barbatum and A. leucoderme. Acer nigrum is included in A. sac- PINACEAE (Pine Family) charum. Pinus †echinata Mill.—shortleaf pine, yellow pine. (Killip & Blake 1935). AMARANTHACEAE (Amaranth Family) ϩtaeda L.—loblolly pine. (1) E.P. Killip 36646, Amaranthus albus L.—tumbleweed. (Amaranthus 24 Jan 1943. Mainland, four trees east of upper graecizans L.) (1) E.P. Killip 13474, 8 Sep trail, not far from Canal. Comments: Planted by 1930. Sandbar, east end. A.K. Fisher. Long gone. hybridus L.—common pigweed, smooth pigweed. virginiana Mill.—scrub pine, Virginia pine, Jersey (A. retroﬂexus L., misapplied (Ward 1881)). (7) pine. (P. inops (Ward) Sol. ex Aiton). (3) M. E.C. Leonard & N. Hotchkiss 3532, 9 May Beyersdorfer 438, 31 Oct 1982. Cabin Hill. 1961. West end, low weedy bank. Comments: Gone by 2003. SPINOSUS L.—spiny amaranth, thorny amaranth. Tsuga ϩcanadensis (L.) Carrie`re—eastern hemlock. (8) W.J. Kress & M. Butts 04-7541, 23 Jun (3) M. Beyersdorfer 262, 12 Sep 1982. Com- 2004. SW shore: beach. I. ments: Planted by A.K. Fisher on Island and Iresine rhizomatosa Standl.—bloodleaf, Juda’s- Mainland (McAtee 1930, pp. 53–54). Tree about bush. (5) P.C. Standley 12500, 3 Oct 1915 [2 4 m high still persisting on island in 1982 (M. sheets: holotype & isotype]. Comments: This Beyersdorfer), but gone by 2003. species described from Island (Standley 1915). Extirpated for many years. DICOTYLEDONS

ACANTHACEAE (Water-Willow Family) ANACARDIACEAE (Sumac Family) Justicia americana (L.) Vahl—water-willow, Amer- Rhus copallinum L.—shining sumac. (3) M. Be- ican water-willow, dense-flowered water-willow. yersdorfer 405, 31 Oct 1982. Cactus Rock. (Dianthera americana L.) (5) M. Beyersdorfer †glabra L.—smooth sumac. (1) E.P. Killip 13227, 117, 26 May 1983. East end of Island, in wa- 14 Jul 1928. [Mainland], edge of Fisher Garden. ter. I. typhina L.—staghorn sumac. (2) M. Beyersdorfer Ruellia ϩcaroliniensis (J.F. Gmel.) Steud.—hairy 432, 31 Oct 1982. Sycamore Cove on the banks ruellia, slender ruellia. (R. parviflora (Nees) toward east end. Britton) (4) E.C. Leonard & N. Hotchkiss 3197, Toxicodendron radicans (L.) Kuntze—poison-ivy. 23 Jul 1960. Between Cabin Hill and west end, (Rhus radicans L., R. toxicodendron L.) (6) W.J. along trail. Comments: Three of the four spec- Kress & M. Butts 04-7470, 13 May 2004. On imens were collected before 1935. One was rock at W side of Cactus Rock. I. identified as R. strepens, but the two identified †vernix (L.) Kuntze—poison-sumac. (Rhus vernix as R. parviflora apparently were overlooked by L.) Comments: Reported by Killip & Blake Killip & Blake in 1935 and 1953. (1935) from Mainland but specimen now miss- strepens L.—smooth ruellia. (2) S.F. Blake s.n., ing; they added: ‘‘Extinct.’’ 19 Oct 1933. On hill west of Cabin [West Knoll]. ANNONACEAE (Custard-apple Family) ACERACEAE (Maple Family) Asimina triloba Dunal—pawpaw. (13) W.J. Kress & Acer negundo L.—boxelder, ash-leaved maple. (Ru- M. Butts 04-7433, 6 May 2004. Along path to lac negundo (L.) Hitchc.) (7) W.J. Kress & M. cabin. I.

APIACEAE (UMBELLIFERAE) W.L. McAtee spring list, 30 Mar 1913 (WBFC (Parsley Family) Archives). W.

Angelica †venenosa (Greenway) Fernald—hairy an- APOCYNACEAE (Dogbane Family) gelica. (A. villosa (Walter) Britton, Sterns & Poggenb.) (1) E.P. Killip 13318, 9 Sep 1928. Apocynum cannabinum L.—Indian-hemp, hemp Mainland, Stewart Farm. dogbane. (A. pubescens R. Br., A. sibiricum Chaerophyllum procumbens (L.) Crantz—spread- Jacq.) (9) W.J. Kress & N.A. Bourg 04-7575, 31 ing chervil. (4) E.C. Leonard & N. Hotchkiss Jul 2004. On rock outcrop at E end. Comments: 3489, 9 May 1961. West end ridge. M. Very variable species. See also A. medium in ϩ†tainturieri Hook.—southern chervil. (1) P.C. ‘‘Excluded Species’’ in Introduction. I. Standley 11418, 9 May 1915. Mainland. Com- ments: Originally identiﬁed as C. procumbens, AQUIFOLIACEAE (Holly Family) but probably C. tainturieri, though intermediate. Ilex opaca Aiton—American holly. (2) W.J. Kress & Cicuta maculata L.—common water-hemlock, spot- M. Butts 04-7485, 20 May 2004. Central plain ted cowbane. (1) E.P. Killip 32599, 19 Jun1938. (west of cabin). Comments: Included by Killip East end. & Blake (1935) with comment, ‘‘Formerly one CONIUM ϩMACULATUM L.—poison-hemlock. (4) plant grew on Island.’’ Known to be introduced W.J. Kress & M. Butts 04-7474, 13 May 2004. to both Island and Mainland (McAtee 1930, pp. Directly below Cactus Rock (SW). I. 53–54) and, thus, probably not native there. I. Cryptotaenia canadensis (L.) DC.—honewort, wild †verticillata (L.) A. Gray—black-alder, winterber- chervil. (Deringa canadensis (L.) Kuntze). (8) ry. (2) E.P. Killip & 31262, 22 Jul 1934. Main- E.F. Wells, R.L. Brown & V.S. Murthy 4387, 30 land, Northwest Swamp. M. Jul 1997. Floodplain. I. DAUCUS CAROTA L.—Queen Anne’s-lace, wild carrot. ARALIACEAE (Ginseng Family) (5) W.J. Kress & M. Butts 04-7569, 22 Jul 2004. Along beach at East End. I. Aralia †spinosa L.—Hercules’-club, devil’s-walk- Erigenia bulbosa (Michx.) Nutt.—harbinger-of- ing-stick, angelica-tree. (1) E.P. Killip 31268, spring. (8) M. Beyersdorfer 12, 25 Mar 1983. 29 Jul 1934. Mainland, northwest corner of Gap woods toward channel side. Fisher Garden. Comments: Introduced (McAtee Osmorhiza claytonii (Michx.) C.B. Clarke—hairy 1930, p. 54). sweet-cicely, bland sweet-cicely, sweet-jarvil. HEDERA ϩ†HELIX L.—English ivy. Comments: (2) A.S. Hitchcock 12764, 6 Jun 1915. Mainland, well established at Lock House of longistylis (Torr.) DC.—anise-root, smooth sweet- Lock 11, C&O Canal, and elsewhere. Present cicely, long-styled sweet-cicely. (11) W.J. Kress for years without being recorded. M. & M. Butts 04-7444, 6 May 2004. Along path directly below (ENE) terrace. I. ARISTOLOCHIACEAE (Birthwort Family) PASTINACA SATIVA L.—wild parsnip, parsnip. (Killip Aristolochia serpentaria L.—Virginia-snakeroot. & Blake 1935). (1) A.S. Hitchcock 15822, 16 Sep 1917. Sanicula canadensis L.—black snakeroot, Canada Asarum canadense L.—wild ginger. (A. reﬂexum sanicle. (5) T.H. Kearney & W.R. Maxon 1, 24 E.P. Bicknell). (11) W.J. Kress & M. Butts 04- Jul 1910. Edge of rocky woods. W. 7441, 6 May 2004. Along path directly below odorata (Raf.) K.M. Pryor & L.R. Philippe—clus- (ENE) terrace. I. tered snakeroot, fragrant snakeroot, fragrant sanicle. (S. gregaria E.P. Bicknell). (9) E.F. Wells, ASCLEPIADACEAE (Milkweed Family) R.L. Brown & V.S. Murthy 4341, 1 Jul 1997. Floodplain. I. Asclepias incarnata L.—swamp milkweed. (A. in- Thaspium †barbinode (Michx.) Nutt.—hairy-joint- carnata var. pulchra (Ehrh. ex Willd.) Pers., A. ed meadow-parsnip, bearded meadow-parsnip. pulchra Ehrh. ex Willd.) (11) W.J. Kress & M. (1) E.P. Killip 13228, 14 Jul 1928. [Mainland], Butts 04-7565, 22 Jul 2004. Above channel near woods near Fisher Garden. W point, across from I-495 bridge. I. Zizia ϩaurea (L.) W.D.J. Koch—common golden- ϩquadrifolia Jacq.—four-leaved milkweed. (1) Alexanders. (Thaspium aureum (L.) Nutt.) (5) E.S. Steele s.n., 31 May 1897. Comments: M. Beyersdorfer 14, 11 Apr 1982. East tip. Steele’s specimen overlooked by Killip & Blake Comments: A.S. Hitchcock 12479, 1915, and (1935, 1953). P.C. Standley 11286, 1915, apparently over- †syriaca L.—common milkweed. (Killip & Blake looked by Killip and Blake (1935, 1953). In a 1935).

†tuberosa L.—butterfly-weed, pleurisy-root. (1) divaricatus L.—white wood aster, common white E.P. Killip 13226, 14 Jul 1928. Mainland, near heart-leaved aster. (Eurybia divaricata (L.) G.L. Fisher Garden. Nesom). (13) W.J. Kress & N.A. Bourg 04-7585, Cynanchum laeve (Michx.) Pers.—honeyvine, sand- 29 Aug 2004. On rocks on W side, below cab- vine. (Ampelamus albidum (Nutt.) Britton, Gon- in. I. olobus laevis Michx.) (16) W.J. Kress & N.A. †infirmus Michx.—cornel-leaved aster, Appala- Bourg 04-7620, 5 Sep 2004. On rock outcrop at chian flat-topped white aster. (Doellingeria in- E end. I. firma (Michx.) Greene). (1) E.P. Killip 13319, Matelea obliqua (Jacq.) Woodson—(Gonolobus ob- 9 Sep 1928. [Mainland], edge of Stewart Farm. liquus (Jacq.) R. Br. ex J. Schult., Vincetoxicum lanceolatus Willd.—panicled aster, tall white aster. obliquum (Jacq.) Britton). (4) E.P. Killip 32116, (A. paniculatus Lam., A. simplex Willd., Sym- 13 Jun 1937. Just west of Gap between Cabin phyotrichum lanceolatum (Willd.) G.L. Nesom). and West knolls, close to trail. (12) S.G. Shetler & E.R. Shetler 2004.33, 11 Oct 2004. West end, floodplain. I. ASTERACEAE (COMPOSITAE) (Aster Family) ϩlateriflorus (L.) Britton—calico aster, starved aster, goblet aster. (A. vimineus Lam., Symphy- Achillea millefolium L.—common yarrow, milfoil. otrichum lateriflorum (L.) A. Love & D. Love). (3) P.C. Standley 11856, 24 Jul 1915. (4) E.C. Leonard & N. Hotchkiss 3216, 27 Sep Ageratina altissima (L.) R.M. King & H. Rob.— 1960. High Knoll, south slope. Comments: T.H. white snakeroot. (Ageratum altissimum L., Eu- Kearney’s nos. 206 and 220, both collected Oct. patorium rugosum Houtt., E. urticifolium Rei- 1, 1905, and clearly duplicates, apparently were chard). (9) W.J. Kress & N.A. Bourg 04-7589, not seen by Killip and Blake (1935, 1953). I. 29 Aug 2004. Among rocks, W side below Cab- novae-angliae L.—New England aster. (Lasallea in. I. novae-angliae (L.) Semple & Brouillet, Sym- Ambrosia artemisiifolia L.—common ragweed. (A. phyotrichum novae-angliae (L.) G.L. Nesom, elatior E.F. Wells, R.L. Brown & V.S. L.) (2) Virgulus novae-angliae (L.) Reveal & Keener). Murthy 4495, 20 Sep 1997. Floodplain. (2) E.P. Killip 32641, 24 Sep 1938. ‘‘Barrens’’ trifida L.—giant ragweed. (7) E.F. Wells, R.L. near new ferry posts. Brown & V.S. Murthy 4873, 31 Aug 1997. patens Aiton—late purple aster, clasping aster. Floodplain. (Lasallea patens (Aiton) Semple & Brouillet, Antennaria plantaginifolia (L.) Richardson—plan- Symphyotrichum patens (Aiton) G.L. Nesom, tain-leaved everlasting, plantain-leaved pussy- Virgulus patens (Aiton) Reveal & Keener). (2) toes. (A. arnoglossa Greene, A. fallax Greene, A.S. Hitchcock 15865, 7 Oct 1917. A. parlinii Fernald). (8) M. Beyersdorfer 65, 2 pilosus Willd.—white heath aster, awl aster. (A. er- May 1983. Cabin Hill summit, west side. icoides L., misapplied, Symphyotrichum pilosum ANTHEMIS ARVENSIS L.—corn chamomile, field (Willd.) G.L. Nesom). (13) N. Hotchkiss & E.C. chamomile. (3) S.F. Blake s.n., 20 Oct 1936. Waste weedy ground formed by 1936 flood. Leonard 3559, 9 May 1961. Upper Gap [3 sheets]. W. ARCTIUM MINUS Bernh.—common burdock. (1) S.F. Blake s.n., 19 Oct 1933. North of West Knoll. prenanthoides Muhl. ex Willd.—crooked-stem Arnoglossum atriplicifolium (L.) H. Rob.—pale In- aster, zigzag aster. (Symphyotrichum prenan- dian-plantain. (Cacalia atriplicifolia L., Mesa- thoides (Muhl. ex Willd.) G.L. Nesom). (2) E.P. denia atriplicifolia (L.) Raf.) (4) E.C. Leonard Killip 13333, 22 Sep 1928. Mainland, lower & N. Hotchkiss 3336, 27 Sep 1960. River trail trail. W. near base of Cabin Hill. †puniceus L.—purple-stemmed aster, bristly aster. ARTEMISIA ANNUA L.—annual wormwood. (12) W.J. (A. salicifolius Lam., Symphyotrichum puniceum Kress & N.A. Bourg 04-7622, 5 Sep 2004. On (L.) A. Lo¨ve&D.Lo¨ve). (1) E.P. Killip 31341, rock outcrop at E end. I. 29 Sep 1934. Mainland, Stewart Farm. ϩVULGARIS L.—common mugwort. (1) E.F. Wells, Bidens ARISTOSA (Michx.) Britton—midwestern tick- R.L. Brown & V.S. Murthy 4377, 30 Jul 1997. seed-sunflower. (6) E.P. Killip 36659, 16 Sep Floodplain. M. 1943. ‘‘Barrens’’ along channel. Aster cordifolius Michx.—common blue wood aster, bipinnata L.—Spanish-needles. (5) E.C. Leonard common blue heart-leaved aster. (A. sagittifolius & N. Hotchkiss 3248, 27 Sep 1960. Prospect Wedem. ex Willd., Symphyotrichum cordifolium Rock [2 sheets]. (L.) G.L. Nesom, S. sagittifolium (Wedem. ex cernua L.—nodding bur-marigold, stick-tight. (B. Willd.) G.L. Nesom). (9) E.F. Wells, R.L. Brown chrysanthemoides Michx., in part, B. leptomeria & V.S. Murthy 5185, 21 Sep 1997. Floodplain. I. Greene (type from DC area)). (10) M. Beyers-

dorfer 311, 25 Sep 1982. East end, near river’s ‘‘new record for D.C. area’’ (Killip & Blake edge. 1953). frondosa L.—devil’s beggar-ticks, stick-tight. (5) Eclipta prostrata (L.) L.—eclipta, yerba-de-tago. E.C. Leonard & N. Hotchkiss 3233, 27 Sep (E. alba (L.) Hassk.) (5) E.F. Wells, R.L. Brown 1960. West tip. W. & V.S. Murthy 4546, 21 Sep 1997. Flood- polylepis S.F. Blake—Ozark tickseed-sunflower. plain. M. (5) E.F. Wells, R.L. Brown & V.S. Murthy 5164, Elephantopus carolinianus Raeusch.—elephant’s- 12 Jun 1997. Floodplain. foot, leafy elephant’s-foot. (4) M. Beyersdorfer TRIPARTITA L.—beggar-ticks, tickseed. (B. comosa 325, 26 Sep 1982. East end. (A. Gray) Wiegand, B. connata Muhl. ex Willd.) Erechtites hieraciifolia (L.) Raf.—fireweed, pile- (10) E.C. Leonard & N. Hotchkiss 3526, 9 May wort, sneezeweed. (3) E.C. Leonard 3469, 29 1961. West end, low weedy bank. Oct 1960. High Knoll. W. vulgata Greene—tall beggar-ticks, tall stick-tight, Erigeron annuus (L.) Pers.—daisy fleabane, annual common beggar-ticks. (5) A.S. Hitchcock 15717, fleabane, white-top. (7) W.J. Kress & N.A. 9 Sep 1917. Bourg 04-7579, 7 Aug 2004. W end, on south- Centaurea CYANUS L.—bachelor’s-button, cornflow- facing shoreline, 150 m from I-495. I. er, bluebottle. (1) E.P. Killip 31866, 5 Jul 1936. philadelphicus L.—Philadelphia fleabane, com- ‘‘Barrens’’ along channel. mon fleabane, Philadelphia daisy. (5) M. Bey- MACULOSA Lam.—spotted knapweed. (C. bieber- ersdorfer 80, 10 May 1983. East end near flats steinii DC.) (1) E.P. Killip 32159, 1 Aug 1937. on river side. ‘‘Barrens’’ near new ferry posts. pulchellus Michx.—robin’s-plantain. (E. bellidi- Chrysogonum virginianum L.—golden-star, gold- folius Muhl. ex Willd.) (1) A.S. Hitchcock en-knees, green-and-gold. (4) M. Beyersdorfer 12563, 9 May 1915. 113, 26 May 1983. Mainland, east of path, mid- strigosus Muhl. ex Willd.—lesser daisy fleabane, way between Canal—dock. rough fleabane, white-top. (E. ramosus (Walter) E.P. Killip Chrysopsis †mariana (L.) Elliott—Maryland gold- Britton, Sterns & Poggenb.) (2) 32659, 9 Jul 1939. Gap near upper end. en-aster, shaggy golden-aster. (Killip & Blake Eupatorium altissimum L.—tall thoroughwort, tall 1935). boneset. (8) E.C. Leonard & N. Hotchkiss 3556, CICHORIUM INTYBUS L.—chicory. (1) E.P. Killip 9 May 1961. Upper Gap, between rocks. 31884, 12 Jul 1936. Near unused ferry posts. coelestinum L.—mistflower, blue-boneset, wild- Cirsium altissimum (L.) Hill—tall thistle. (6) E.P. ageratum, hardy-ageratum. (Conoclinium coe- Killip 31334, 24 Sep 1934. In front of cabin. lestinum (L.) DC.) (6) W.J. Kress & M. Butts discolor (Muhl. ex Willd.) Spreng.—field thistle. 04-7564, 22 Jul 2004. North shore, mid-island (2) E.P. Killip 32228, 19 Sep 1937. Between along channel. I. Gap and upper part of channel, about halfway hyssopifolium L.—hyssop-leaved boneset, hys- down. sop-leaved thoroughwort. (Eupatorium torrey- VULGARE (Savi) Ten.—bull thistle, common this- anum Short & Peter). (3) E.C. Leonard & N. tle. (C. lanceolatum (L.) Hill., misapplied). (1) Hotchkiss 3262, 27 Sep 1960. Prospect E.P. Killip 32160, 1 Aug 1937. ‘‘Barrens’’— Rock. W. along channel toward east end, near ‘‘tomato perfoliatum L.—boneset, thoroughwort. (2) E.C. site.’’ W. Leonard 3589, 9 May 1961. Bank of channel Conyza canadensis (L.) Cronquist—horseweed, above ferry. colt’s-tail. (Erigeron canadensis L., Leptilon purpureum L.—purple-node joe-pye-weed, sweet canadense (L.) Britton). (2) E.C. Leonard & N. joe-pye-weed, green-stemmed joe-pye-weed. Hotchkiss 3261, 27 Sep 1960. Prospect (Eupatoriadelphus purpureus (L.) R.M. King & Rock. W. H. Rob.) (4) S.G. Shetler & E.F. Wells 2004.13, Coreopsis TINCTORIA Nutt.—golden coreopsis, 21 Jul 2004. Mainland, near Crossing Rocks. I. plains tickseed. (1) S.F. Blake 12091, 20 Oct rotundifolium L.—round-leaved thoroughwort, 1936. Waste weedy ground formed by 1936 round-leaved boneset. (Eupatorium pubescens flood. Muhl. ex Willd.) (6) M. Beyersdorfer 138, 11 †verticillata L.—whorled coreopsis, whorled tick- Jul 1982. East end just off the trail. seed, thread-leaved tickseed. (1) E.P. Killip ϩserotinum Michx.—late-flowering thorough- 31045, 25 Jun 1933. Mainland, along main trail. wort, late-flowering boneset. (3) S.G. Shetler & CREPIS PULCHRA L.—small-flowered hawk’s-beard. E.R. Shetler 2004.31, 11 Oct 2004. West end, (1) E.P. Killip 31846, 5 Jul 1936. ‘‘Barrens’’ sandy depression on floodplain. I. along channel just below ferry. Comments: sessilifolium L.—upland boneset. (2) E.P. Killip

32663, 6 Aug 1939. Upper Gap, west side at E.P. Killip 31126, 24 Sep 1933. Mainland, west edge of woods. of middle gate. Euthamia graminifolia (L.) Nutt.—grass-leaved canadensis L.—wild lettuce, tall lettuce. (L. sag- goldenrod, lance-leaved goldenrod, common ittifolia Elliott, L. steelei Britton). (2) E.P. Killip flat-topped goldenrod. (Solidago graminifolia 32165, 2 Aug 1937. Mainland, lower trail to- (L.) Salisb.) (3) E.P. Killip 32947, 6 Oct 1940. ward east end. W. River side of Upper Gap. floridana (L.) Gaertn.—Florida blue lettuce, Flor- GALINSOGA PARVIFLORA Cav.—smooth galinsoga, ida lettuce, woodland lettuce. (L. villosa Jacq.) lesser quickweed. (5) W.J. Kress & M. Butts 04- (5) E.P. Killip 31114, 4 Sep 1933. Mainland, 7572, 11 Jun 2004. Mid-island near north along main trail. M. shore. I. SERRIOLA L.—prickly lettuce, compass-plant. (L. QUADRIRADIATA Ruiz & Pav.—raceweed, common scariola L., L. virosa L.) (1) E.P. Killip 31925, quickweed. (G. caracasana (DC.) Sch. Bip., G. 9 Aug 1936. ‘‘Barrens’’ along channel below ciliata (Raf.) Blake). (10) E.C. Leonard & N. ferry landing. Hotchkiss 3581, 9 May 1961. Bank of channel LAPSANA ϩCOMMUNIS L.—nipplewort. (1) S. Wiser above ferry [May collection date question- & W. Burket 31, 14 Aug 1986. East end, bank able]. M. of channel near Crossing Rocks. Open flood- Gnaphalium obtusifolium L.—fragrant cudweed, plain area. sweet everlasting. (1) E.P. Killip 31135, 1 Oct LEUCANTHEMUM †VULGARE Lam.—ox-eye daisy. 1933. Near cabin. (Chrysanthemum leucanthemum L.) (1) E.P. purpureum L.—purple cudweed. (1) E.P. Killip Killip 13327, 9 Sep 1928. [Mainland], Stewart 31894, 12 Jul 1936.‘‘Barrens’’ near new ferry Farm. posts. Polymnia canadensis L.—white-flowered leafcup, Helenium autumnale L.—yellow sneezeweed, com- pale-flowered leafcup, small-flowered leafcup. mon sneezeweed. (4) E.F. Wells, R.L. Brown & (5) M. Beyersdorfer 441, 31 Oct 1982. V.S. Murthy 5169, 12 Jun 1997. Floodplain. uvedalia L.—yellow-flowered leafcup, large-flow- flexuosum Raf.—purple sneezeweed, southern ered leafcup, bear’s-foot. (5) E.C. Leonard & N. sneezeweed. (H. nudiflorum Nutt.) (1) E.P. Kil- Hotchkiss 3209, 27 Sep 1960. High Knoll, east lip 32631, 31 Aug 1938. River side of Gap. slope [2 sheets]. W. Helianthus †ANNUUS L.—common sunflower. (2) Prenanthes serpentaria Pursh—lion’s-foot, gall-of- E.P. Killip 32180, 15 Aug 1937. [Mainland], the-earth, rattlesnake-root. (1) T.H. Kearney Stewart Farm. 203, 1 Oct 1905. decapetalus L.—thin-leaved sunflower, forest sun- Rudbeckia †fulgida Aiton—orange coneflower, bril- flower. (11) E.F. Wells, R.L. Brown & V.S. Mur- liant coneflower, eastern coneflower. (1) E.P. thy 4492, 20 Sep 1997. Floodplain. Killip 13735, 13 Sep 1931. [Mainland], Stewart divaricatus L.—woodland sunflower, divaricate Farm. sunflower. (1) E.P. Killip 32666, 13 Aug 1939. hirta L.—black-eyed-Susan. (R. serotina Nutt.) Gap at upper end, near channel side. (2) E.P. Killip & 32654, 24 Jun 1939. ‘‘Bar- occidentalis Riddell—naked-stemmed sunflower, rens’’ near trail to ferry. western sunflower, McDowell’s sunflower. (H. laciniata L.—tall coneflower, green-headed cone- dowellianus M.A. Curtis). (2) E.P. Killip 32938, flower, cut-leaved coneflower. (10) W.J. Kress 25 Aug 1940. ‘‘Barrens,’’ near upper ferry post. & N.A. Bourg 04-7576, 31 Jul 2004. E end, on tuberosus L.—Jerusalem-artichoke. (2) E.P. Killip river bank at water’s edge. I. 31955, 7 Sep 1936. ‘‘Barrens,’’ near tree bridge triloba L.—three-lobed coneflower. (8) E.P. Killip [2 sheets]. 32935, 24 Aug 1940. Flood-swept land. Heliopsis helianthoides (L.) Sweet—ox-eye, false Senecio aureus L.—golden ragwort, heart-leaved sunflower, sunflower-everlasting. (4) W.J. Kress groundsel. (8) M. Beyersdorfer 41, 28 Apr 1983. & M. Butts 04-7567, 22 Jul 2004. Along trail Northwest of Cabin Hill in the Gap—channel near E point. I. side. I. Hieracium venosum L.—rattlesnake-weed, veiny †obovatus Muhl.—round-leaved ragwort, running hawkweed. (3) M. Beyersdorfer 16-84, 31 May groundsel, squaw-weed. (1) S.F. Blake 11883, 5 1984. West End. Rocky ledge. May 1935. Mainland, near pond off upper path. Krigia virginica (L.) Willd.—dwarf-dandelion, Vir- Solidago bicolor L.—silverrod. (5) E.C. Leonard & ginia dwarf-dandelion. (6) R.S. Cowan 1693, 4 N. Hotchkiss 3224, 27 Sep 1960. Summit of Jun 1961. West slope of Cabin Hill. I. High Knoll. Lactuca biennis (Moench) Fernald—tall blue let- caesia L.—blue-stem goldenrod, wreath golden- tuce. (L. spicata (Lam.) Hitchc., misapplied.) (3) rod, axillary goldenrod. (9) M. Beyersdorfer

307, 25 Sep 1982. Trail from east end up Cabin & N. Hotchkiss 3314, 27 Sep 1960. Upper Gap. Hill, before Fern Valley. I. Comments: Earlier specimens of T.H. Kearney canadensis L.—tall goldenrod, Canada goldenrod, (1903), J.C. Crawford (1914) and P.C. Standley common goldenrod. (S. altissima L.) (12) E.C. (1915) apparently not seen by Killip & Blake Leonard 3462, 29 Oct 1960. Upper Gap. (1935, 1953). W. flexicaulis L.—zigzag goldenrod, broad-leaved noveboracensis (L.) Michx.—New York iron- goldenrod. (7) E.F. Wells, R.L. Brown & V.S. weed. (7) W.J. Kress & N.A. Bourg 04-7623, 5 Murthy 4488, 20 Sep 1997. Floodplain. I. Sep 2004. At edge of Island next to trail before gigantea Aiton—late goldenrod, smooth golden- reaching rock outcrops. I. rod. (S. serotina Aiton). (11) E.F. Wells, R.L. Xanthium strumarium L.—common cocklebur. (X. Brown & V.S. Murthy 5172, 12 Sep 1997. americanum Walter, X. chinense Mill., X. com- Floodplain. mune Britton, X. italicum Moretti, X. pensylvan- juncea Aiton—early goldenrod. (6) M. Beyersdor- icum Wallr., X. pungens Wallr., X. saccharatum fer 217, 28 Aug 1982. Cabin Hill, west slope. Wallr.) (14) E.F. Wells, R.L. Brown & V.S. Mur- ϩnemoralis Aiton—gray goldenrod, old-field thy 4550, 21 Sep 1997. Floodplain. M. goldenrod, dwarf goldenrod. (5) E.C. Leonard & N. Hotchkiss 3315, 27 Sep 1960. Upper Gap. BALSAMINACEAE (Touch-me-not Family) Comments: T.H. Kearney 140 (1903) and 214 (1905) apparently not seen by Killip & Blake Impatiens capensis Meerb.—spotted touch-me-not, (1935, 1953). orange touch-me-not, orange jewelweed. (I. bi- ϩrupestris Raf.—riverbank goldenrod. (2) T.H. flora Walter). (6) W.J. Kress & M. Butts 04- Kearney 186, 30 Aug 1903. Comments: T.H. 7518, 17 Jun 2004. Floodplain, mid-island, Kearney 123 (1903) and 186 (1903) apparently north shore. I. not seen by Killip & Blake (1935, 1953). pallida Nutt.—pale touch-me-not, yellow touch- simplex Kunth—riverbank goldenrod. (S. race- me-not, yellow jewelweed. (4) E.C. Leonard & mosa Greene). (10) S.G. Shetler & E.F. Wells N. Hotchkiss 3561, 9 May 1961. Bank of chan- & R.J. Soreng 2004.38, 30 Oct 2004. West end, nel above ferry. on boulders at river’s edge. I. ulmifolia Muhl. ex Willd.—elm-leaved goldenrod. BERBERIDACEAE (Barberry Family) W.J. Kress & N.A. Bourg 04-7582, (10) 7 Aug BERBERIS ϩTHUNBERGII DC.—Japanese barberry. (2) 2004. In grassy area next to cabin on W side. I. M. Beyersdorfer 18, 11 Apr 1982. Cabin Hill ϩ SONCHUS ASPER (L.) Hill—spiny-leaved sow-this- base, northwest side (Gap). M. tle. (1) S.G. Shetler & E.F. Wells 2004.16, 21 Caulophyllum thalictroides (L.) Michx.—blue co- Jul 2004. Sandy riverbank at edge of woods. I. hosh. (1) A.S. Hitchcock 12449, 25 Apr 1915. I. Synosma suaveolens (L.) Raf. ex Britton—sweet- Jeffersonia diphylla (L.) Pers.—twinleaf. (13) W.J. scented Indian-plantain, hastate Indian-plantain. Kress 04-7486, 20 May 2004. Central plain (Cacalia suaveolens L.) (4) E.P. Killip 36631, (west of cabin). I. 17 Jul 1942. East end. Podophyllum peltatum L.—mayapple, mandrake. TARAXACUM LAEVIGATUM (Willd.) DC.—red-seeded (7) M. Beyersdorfer 94, 10 May 1983. Gap, low- dandelion. (Leontodon erythrospermum (Andrz. lands. M, W. ex Besser) Britton, T. erythrospermum Andrz. A.S. Hitchcock 12476, ex Besser). (1) 2 May BETULACEAE (Birch Family) 1915. OFFICINALE F.H. Wigg.—common dandelion. Alnus serrulata (Aiton) Willd.—common alder, (Leontodon taraxacum L.) (3) M. Beyersdorfer smooth alder, hazel alder. (A. rugosa (Du Roi) 55, 28 Apr 1983. Mainland, path from Lock 11 Spreng., misapplied). (1) E.P. Killip 31185, 30 to Crossing Rocks. W. May 1934. Mainland, Northwest Swamp. Com- Verbesina alternifolia (L.) Britton ex Kearney— ments: ‘‘Formerly on Island (no specimen pre- wingstem. (Actinomeris alternifolia (L.) DC., served); still on mainland’’ (Killip & Blake Ridan alternifolia (L.) Britton). (12) W.J. Kress 1935). & N.A. Bourg 04-7587, 29 Aug 2004. In bot- Betula nigra L.—river birch, red birch. (4) E.F. tomland below rocks on W side below cabin. I. Wells, R.L. Brown & V.S. Murthy 4444, 31 Aug occidentalis (L.) Walter—yellow crownbeard, 1997. Floodplain. southern flatseed-sunflower. (4) E.P. Killip Carpinus caroliniana Walter—American hornbeam, 32945, 28 Sep 1940. Upper Gap. W. ironwood, blue-beech, musclewood. (5) M. Be- Vernonia ϩglauca (L.) Willd.—broad-leaved iron- yersdorfer 96, 10 May 1983. Path to Cabin Hill weed, Appalachian ironweed. (4) E.C. Leonard through Fern Valley. I.

Ostrya virginiana (Mill.) K. Koch—hop hornbeam, lyrata L.—lyre-leaved rockcress. (6) E.P. Killip ironwood. (11) W.J. Kress & M. Butts 04-7543, 36829, 1 Jun 1947. East end. 23 Jun 2004. Cactus Rock (E side). I. shortii (Fernald) Gleason—Short’s rockcress. (A. dentata (Torr.) Torr. & A. Gray). (4) P.C. Stan- BIGNONIACEAE (Trumpet-creeper Family) dley 13111, 30 Apr 1916. Alluvial flats. BARBAREA VERNA (Mill.) Asch.—early winter-cress. Campsis radicans (L.) Seem. ex Bureau—trumpet- (Campe verna (Michx.) Heller). (3) E.P. Killip creeper. (Bignonia radicans L.) (8) W.J. Kress 13356, 30 May 1930. River side of Island. W. & N.A. Bourg 04-7578, 7 Aug 2004. W side, on VULGARIS W.T. Aiton—common winter-cress, yel- rock outcrop next to river, 75 m from I-495. I. low-rocket. (Campe barbarea (L.) W. Wight ex CATALPA BIGNONIOIDES Walter—common catalpa, Piper, C. stricta (Andrz.) W. Wight ex Piper). southern catalpa, Indian-bean. (2) W.J. Kress & (6) W.J. Kress & M. Butts 04-7451, 6 May 2004. M. Butts 04-7560, 15 Jul 2004. W point, rocks E point, at river’s edge. I. near I-495 bridge. Comments: Introduced to BRASSICA JUNCEA (L.) Czern.—Indian mustard, Chi- Mainland (McAtee 1930, p. 54). I. nese mustard, brown mustard. (2) A.S. Hitch- cock 15647, 29 Jul 1917. BORAGINACEAE (Borage Family) NIGRA (L.) W.D.J. Koch—black mustard. (3) S.G. Shetler & S.S. Orli 2004.10, ECHIUM VULGARE L.—viper’s bugloss, blueweed, 30 Jun 2004. Sandy blue-devil, blue-thistle. (1) E.P. Killip 32625, 10 riverbank at edge of woods. I. Jul 1938. ‘‘Barrens’’ south of upper new ferry RAPA L.—turnip, bird’s rape, field mustard. (B. post. campestris L.) (3) E.P. Killip & N. Hotchkiss & Hackelia virginiana (L.) I.M. Johnst.—beggar’s- J.R. Swallen 31996, 11 Oct 1936. ‘‘Barrens’’ lice, stickseed. (Lappula virginiana (L.) near ferry landing. Greene). (2) P.C. Standley 11839, 24 Jul 1915. CAPSELLA BURSA-PASTORIS (L.) Medik.—shepherd’s- Bursa bursa-pastoris Lithospermum ARVENSE L.—corn gromwell. (Bug- purse. ( (L.) Britton). (2) lossoides arvensis (L.) I.M. Johnst.) (1) J.E. A.S. Hitchcock 12536, 9 May 1915. Benedict & E.P. Killip 32441, 8 May 1938. Up- Cardamine angustata O.E. Schulz—slender tooth- per Gap near channel. wort, Appalachian toothwort. (Dentaria hetero- Mertensia virginica (L.) Pers. ex Link—Virginia phylla O.E. Schulz). (4) M. Beyersdorfer 21, 11 bluebells, bluebells, Virginia-cowslip. (10) W.J. Apr 1983. Cabin Hill, in sloping valley in front Kress & M. Butts 04-7438, 6 May 2004. Ter- of cabin. race. I. bulbosa (Schreb. ex Muhl.) Britton, Sterns & Pog- Myosotis laxa Lehm.—smaller forget-me-not. (3) genb.—spring cress, bulbous cress. (3) A.S. E.F. Wells, R.L. Brown & V.S. Murthy 5145, 12 Hitchcock 12403, 18 Apr 1915. Jun 1997. Floodplain. concatenata (Michx.) Sw.—cut-leaved toothwort, ϩverna Nutt.—spring forget-me-not, early scor- cut-leaved pepperroot, five-parted toothwort. pion-grass, spring scorpion-grass. (M. virginica (Dentaria laciniata Muhl. ex Willd.) (7) M. Be- (L.) Britton, Sterns & Poggenb., misapplied). (1) yersdorfer 48, 28 Apr 1983. Cabin Hill, west N. Hotchkiss & H.K. Svenson s.n., 5 May 1962. side. I. ϩ Rock valley. HIRSUTA L.—hairy bittercress. (1) Leonard and Hotchkiss 3500, 1961 [misidentified as C. parviflora BRASSICACEAE (CRUCIFERAE) ]. M. parviflora (Mustard Family) L.—small-flowered bitter-cress. (7) E.P. Killip 40207, 26 Jan 1950. Mainland, along ALLIARIA PETIOLATA (M. Bieb.) Cavara & Grande— lower trail. garlic-mustard. (A. officinalis Andrz. ex M. pensylvanica Muhl. ex Willd.—Pennsylvania bit- Bieb.) (9) W.J. Kress & M. Butts 04-7435, 6 tercress. (6) S.G. Shetler 2004.5, 15 May 2004. May 2004. Along path to cabin. Directly north Mainland, Northwest Swamp. M. of terrace. I. Draba VERNA L.—whitlow-grass. (3) E.P. Killip ARABIDOPSIS THALIANA (L.) Heynh.—mouse-ear 36817, 20 Apr 1947. Near largest pool in Gap. cress. (2) P.C. Standley 11422, 9 May 1915. ERYSIMUM CHEIRANTHOIDES L.—wormseed mustard. Arabis canadensis L.—sickle-pod. (2) A.S. Hitch- (Cheirinia cheiranthoides (L.) Link) (7) W.J. cock 12771, 6 Jun 1915. Kress & M. Butts 04-7542, 23 Jun 2004. SW laevigata (Muhl ex Willd.) Poir.—smooth rock- shore: beach. I. cress. (6) M. Beyersdorfer 29, 14 Apr 1983. HESPERIS MATRONALIS L.—dame’s-rocket, dame’s- West end, path on river side to Rock of Gibral- violet.: (2) W.J. Kress & M. Butts 04-7450, 6 tar. I. May 2004. Near E point, close to river. I.

Lepidium CAMPESTRE (L.) W.T. Aiton—field-cress, terrestris Raf.—Austin’s water-starwort. (C. aus- cow-cress. (2) E.P. Killip 31854, 5 Jul 1936. tinii Engelm.) (1) A.S.Hitchcock 15699, 9 Sep ‘‘Barrens,’’ lower end toward river. 1917. North shore. virginicum L.—wild peppergrass, poor-man’s- pepper. (4) E.P. Killip 31862, 5 Jul 1936. ‘‘Bar- CAMPANULACEAE (Bellflower Family) rens’’ along channel. W. Campanula americana L.—tall bellflower. (5) A.S. NASTURTIUM OFFICINALE W.T. Aiton—watercress. Hitchcock 13005, 15 Jul 1917. (Radicula nasturtium-aquaticum Britten & Ren- Triodanis perfoliata (L.) Nieuw.—Venus’s-looking- dle, Rorippa nasturtium-aquaticum (L.) Hayek., glass, round-leaved triodanis. (Specularia biflo- Sisymbrium nasturtium-aquaticum L.) (2) E.C. ra (Ruiz & Pavoń) Fisch. & C.A. Mey., S. per- Leonard & N. Hotchkiss 3420, 27 Sep 1960. foliata (L.) DC., T. biflora (Ruiz & Pavoń) Channel at ferry landing. Greene). (2) A.S. Hitchcock 12777, 6 Jun 1915. Rorippa palustris (L.) Besser—common yellow- cress, marsh yellow-cress. (Radicula palustris CANNABACEAE (Hemp Family) (L.) Moench, Rorippa hispida (Desv.) Britton, R. islandica (Oeder) Borba´s, misapplied, R. ob- CANNABIS SATIVA L.—hemp, marijuana, pot, grass. tusa (Nutt.) Britton, misapplied). (6) E.F. Wells, (1) S.F. Blake s.n., 24 May 1931. Near cabin. R.L. Brown & V.S. Murthy 4551, 21 Sep 1997. Humulus JAPONICUS Siebold & Zucc.—Japanese Floodplain. I. hop. (H. scandens (Lour.) Merr., misapplied). (9) sessiliflora (Nutt.) Hitchc.—southern yellow-cress. W.J. Kress & N.A. Bourg 04-7615, 29 Aug (Radicula sessiliflora (Nutt.) Greene). (1) A.S. 2004. W side, bottomland below rocks and cab- Hitchcock s.n., 16 Sep 1917. in. I. lupulus T.H. Kearney SYLVESTRIS (L.) Besser—creeping yellow-cress. L.—common hop, hops. (1) (Radicula sylvestris (L.) Druce). (6) S.G. Shetler 31, 19 Aug 1903. W. & E.F. Wells 2004.14, 21 Jul 2004. Rocky islet CAPRIFOLIACEAE (Honeysuckle Family) at east end. I. SISYMBRIUM OFFICINALE (L.) Scop.—hedge mustard. Lonicera JAPONICA Thunb.—Japanese honeysuckle. (Erysimum officinale L.) (1) E.P. Killip 31852, (8) W.J. Kress & M. Butts 04-7466, 13 May 5 Jul 1936. ‘‘Barrens’’ along channel. 2004. E side of Cactus Rock. I. THLASPI PERFOLIATUM L.—perfoliate pennycress. (3) ϩMAACKII (Rupr.) Maxim.—Amur honeysuckle. E.P. Killip 36816, 20 Apr 1947. (3) S.G. Shetler & E.R. Shetler 2004.36, 11 Oct 2004. West end, shrubby area on sandy flood- BUDDLEJACEAE (Butterfly-bush Family) plain. I. Sambucus canadensis L.—common elder, black el- BUDDLEJA DAVIDII Franch.—orange-eye butterfly- derberry, elder, elderberry. (2) W.J. Kress & M. bush. (2) E.P. Killip 32933, 21 Aug 1940. Butts 04-7568, 22 Jul 2004. East end, near Flood-swept land. Comments: ‘‘This persisted point. I. for a few years but is now extinct’’ (Killip & Symphoricarpos orbiculatus Moench—coralberry, Blake 1953). Indian-currant, blackbrush. (5) E.C. Leonard & N. Hotchkiss 3298, 27 Sep 1960. Upper Gap. I. CACTACEAE (Cactus Family) Triosteum ϩ†perfoliatum L.—perfoliate horse-gen- Opuntia humifusa (Raf.) Raf.—eastern prickly-pear. tian, tinker’s-weed, wild-coffee. (8) E.P. Killip (O. compressa (Salisb.) J.F. Macbr., O. opuntia 42246, 25 Sep 1952. Mainland, woods west of (L.) H. Karst., O. vulgaris Mill., misapplied). (5) northwest corner of Stewart Farm. Comments: A.S. Hitchcock 12763, 6 Jun 1915. Comments: Based on collections then in hand, it was listed Photographs (in herbarium) by H.S. Barber from by Killip & Blake (1935) as T. aurantiacum E.P. spring of 1907 show Cactus Rock densely cov- Bicknell, a misidentification. ered by robust plants of this species. When it Viburnum acerifolium L.—maple-leaved viburnum, disappeared is not on record, but it has been dockmackie, maple-leaved arrow-wood. (4) M. gone for many years (see Changing Vegetation Beyersdorfer 114, 26 May 1983. Mainland, high Cover and Flora). rise just to east on path from C&O Lock 11 to ferry dock. M. dentatum CALLITRICHACEAE (Water-starwort Family) † L.—arrow-wood, southern arrow- wood, roughish arrow-wood. (V. pubescens (Ai- Callitriche †STAGNALIS Scop.—European water-star- ton) Pursh, V. scabrellum Torr. & A. Gray ex wort. (4) E.P. Killip 36833, 7 Jun 1947. Main- Chapm.) (3) M. Beyersdorfer 96, 10 Jun 1982. land [2 sheets]. Mainland, near fence by C&O Canal.

ϩ†nudum L.—possum-haw, swamp-haw, smooth Stellaria †longifolia Muhl. ex Willd.—long-leaved withe-rod, naked withe-rod. (1) E.P. Killip stitchwort. (Alsine longifolia (Muhl. ex Willd.) 31471, 4 May 1935. Mainland, pool near old Britton). (1) E.P. Killip 31178, 27 May 1934. spring. Comments: Presumably persisting from Mainland, Barton property. earlier planting (see McAtee 1930, p. 54). MEDIA (L.) Vill.—common chickweed. (Alsine me- prunifolium L.—black-haw. (10) W.J. Kress & M. dia L., S. neglecta Weihe). (7) E.F. Wells, R.L. Butts 04-7506, 8 Jun 2004. Floodplain near NW Brown & V.S. Murthy 4356, 1 Jul 1997. Flood- point. I. plain. I. ϩraﬁnesqueanum Schult.—downy arrow-wood. pubera Michx.—star chickweed. (Alsine pubera (V. afﬁne Bush ex C.K. Schneid.) (5) E.C. Leon- (Michx.) Britton). (8) E.F. Wells, R.L. Brown & ard & N. Hotchkiss 3291, 27 Sep 1960. Between V.S. Murthy 4882, 27 Apr 1998. Floodplain. I. rock outcrops of Upper Gap [2 sheets]. CELASTRACEAE (Staff-tree Family)

CARYOPHYLLACEAE (Pink Family) Celastrus ϩORBICULATUS Thunb.—Oriental bittersweet. (2) W.J. Kress & M. Butts 04-7448, 6 Arenaria SERPYLLIFOLIA L.—sandwort, thyme- May 2004. SE end, river’s edge. I. leaved sandwort. (2) E.P. Killip 32921, 26 May scandens L.—American bittersweet. (3) E.C. 1940. East end. Leonard & N. Hotchkiss 3321, 27 Sep 1960. Cerastium arvense L.—field chickweed. (C. velutin- Upper Gap [2 sheets]. um M. Beyersdorfer 95, Raf.) (8) 10 Jun 1982. Euonymus ϩ†ALATUS (Thunb.) Siebold—winged East end. burning-bush, winged euonymus. (1) M. Bey- GLOMERATUM Thuill.—clammy chickweed. (C. ersdorfer 71, 10 May 1983. C&O Canal Tow- viscosum L., misapplied). (4) S.G. Shetler path just east of Rocky [sic] Run. M. 2004.1, 1 May 2004. East end. I. americanus L.—strawberry-bush. (9) M. Beyers- nutans Raf.—nodding chickweed. (C. longipedun- dorfer 17-84, 31 May 1984. West end. I. culatum Muhl. ex Britton). (2) A.S. Hitchcock atropurpureus Jacq.—wahoo, burning-bush. (2) 12537, 9 May 1915. A.S. Hitchcock 12929, 24 Jun 1917. DIANTHUS ARMERIA E.P. Kil- L.—deptford pink. (2) ϩFORTUNEI (Turcz.) Hand.-Mazz.—climbing eu- lip 32119, 13 Jun 1937. South of West Knoll. onymus. (2) S.G. Shetler 2004.8, 15 May 2004. Paronychia canadensis (L.) Wood—forked-chick- Mainland, along west bank of Rock Run. M. weed, smooth forked-chickweed. (Anychia canadensis (L.) Britton, Sterns & Poggenb.) (4) S. CERATOPHYLLACEAE (Hornwort Family) Wiser 1, 11 Jul 1986. Vicinity of Cactus Rock. ϩ fastigiata (Raf.) Fernald—forked-chickweed, Ceratophyllum †echinatum A. Gray—hornwort, hairy forked-chickweed. (Anychia polygonoides coontail. (C. muricatum Cham., misapplied). (4) Raf.) (1) E.P. Killip 13703, 23 Aug 1931. Near E.P. Killip 36576, 7 Jun 1942, as C. demersum Cactus Rock. L. Comments: In 1953, Killip and Blake added C. demersum SAPONARIA OFFICINALIS L.—bouncing-bet, soapwort. to the species list on the basis of (9) W.J. Kress & M. Butts 04-7550, 1 Jul 2004. P.C. Standley 11771, 27 Jun 1915, which, how- SW Point (rocks). I. ever, was later re-identified by N.C. Fassett as Silene antirrhina L.—sleepy catchfly. (5) E.P. Killip C. echinatum. In 1982, M. Beyersdorfer (350A) 32118, 13 Jun 1937. Where trail crosses Gap collected C. echinatum in the C&O Canal ad- between Cabin Hill and West Knoll. jacent to the Mainland property. †caroliniana Walter—wild pink. (S. pensylvanica CHENOPODIACEAE (Goosefoot Family) Michx.) (1) E.P. Killip 30890, 7 May 1933. Mainland, west of main trail. Chenopodium ALBUM L.—lamb’s-quarters, pigweed. LATIFOLIA Poir.—white campion, white-cockle, (6) S. Wiser & C. Van Metre 65, 3 Oct 1986. evening lychnis. (Lychnis alba Mill., S. praten- East end on bank of channel. M, W. sis (Rafn.) Godr. & Gren.) (5) W.J. Kress & M. AMBROSIOIDES L.—Mexican-tea, wormseed. (6) Butts 04-7546, 23 Jun 2004. SW Point S.G. Shetler, E.F. Wells & R.J. Soreng 2004.40, (rocks). I. 30 Oct 2004. Sandy muddy shores of river. I. nivea (Nutt.) Muhl. ex Otth—snowy campion. (S. ϩberlandieri Moq.—pitseed goosefoot, village alba Muhl.) (3) A.S. Hitchcock 12964, 1 Jul goosefoot. (C. paganum Rchb., misapplied). (1) 1917. P.C. Standley 11444, 9 May 1915., as C. pa- stellata (L.) Aiton—starry campion, widow’s-frill. ganum. Comments: Standley’s specimen appar- (7) W.J. Kress & M. Butts 04-7558, 15 Jul 2004. ently overlooked by Killip & Blake (1935, W point, rocks near I-495 bridge. I. 1953).

CISTACEAE (Rockrose Family) Sicyos angulatus L.—bur-cucumber, one-seeded bur- cucumber, star-cucumber. (7) E.F. Wells, R.L. Lechea racemulosa Michx.—pinweed. (3) S.F. Brown & V.S. Murthy 4518, 21 Sep 1997. Blake s.n., 19 Oct 1933. On hill west of cabin. Floodplain. I.

CONVOLVULACEAE (Bindweed Family) CUSCUTACEAE (Dodder Family) Calystegia sepium (L.) R. Br.—hedge bindweed, Cuscuta gronovii Willd. ex Schult.—common dod- wild morning-glory. (Convolvulus sepium L.) der, Gronovius dodder. (16) S.G. Shetler & E.F. (2) E.P. Killip 31913, 1 Aug 1936. ‘‘Barrens’’ Wells 2004.22, 21 Jul 2004. Northeast of Cabin toward lower end. Hill, along channel. I. Ipomoea HEDERACEA Jacq.—ivy-leaved morning- pentagona Engelm.—five-angled dodder, field glory. (8) M. Beyersdorfer 348, 10 Oct 1982. dodder. (C. arvensis Beyr. ex Engelm., C. cam- East end by river. pestris Yunck.) (3) E.C. Leonard & N. Hotch- lacunosa L.—small-flowered morning-glory, kiss 3389, 27 Sep 1960. Poachers Landing, al- white morning-glory. (18) W.J. Kress & N.A. luvial riverbank. Bourg 04-7619, 5 Sep 2004. E end, on mudflats polygonorum Engelm.—smartweed dodder. (11) near river shore and rock outcrop. I. E.C. Leonard & N. Hotchkiss 3550, 9 May pandurata (L.) G. Mey.—wild potato-vine, wild 1961. Prospect Rock. Comments: Six of the 11 sweet-potato. (5) E.P. Killip 32151, 1 Aug 1937. sheets were collected by Leonard and Hotchkiss Path of flood [sic] toward upper end. and dated 9 May 1961, but May is almost cer- PURPUREA (L.) Roth—common morning-glory. tainly in error. (2) E.C. Leonard & N. Hotchkiss 3376, 27 Sep 1960. Poachers Landing, east end. DIPSACACEAE (Teasel Family)

CORNACEAE (Dogwood Family) DIPSACUS SYLVESTRIS Huds.—common teasel, wild teasel, teasel. (D. fullonum ssp. sylvestris Cornus alternifolia L. f.—alternate-leaved dog- (Huds.) A.R. Clapham). (1) E.P. Killip 32920, wood, pagoda dogwood, green osier. (Killip & 29 Apr 1940. Along channel at north end of Blake 1935). Listed by Killip & Blake as reli- Upper Gap. ably recorded for Island but ‘‘extinct.’’ Also introduced to Mainland (McAtee 1930, p. 54), but EBENACEAE (Ebony Family) not persisting. amomum Mill.—silky dogwood, silky cornel, red- Diospyros virginiana L.—persimmon. (1) E.P. Kil- willow, knob-styled dogwood. (C. obliqua Raf., lip 31286, 19 Aug 1934. Cabin Hill, west slope. C. purpusii Koehne, C. sericea L., misapplied, Comments: Observed by Shetler in 2004 on C. stolonifera Michx., misapplied). (17) E.P. Mainland side of Crossing Rocks at Island’s east Killip 41382, 9 Sep 1951. end. M. florida L.—flowering dogwood. (5) M. Beyers- dorfer 49, 28 Apr 1983. Mainland, near Frog ERICACEAE (Heath Family) Ponds, adjacent to the large Ilex. I. Kalmia latifolia L.—mountain-laurel, ivy-laurel, calico-bush. (3) M. Beyersdorfer 109, 26 May CRASSULACEAE (Stonecrop Family) 1983. Mainland, on rise just to east of path to Penthorum sedoides L.—ditch stonecrop, Virginia ferry dock. One clump on Island at northwest stonecrop. (4) W.J. Kress & N.A. Bourg 04- end. 7618, 3 Sep 2004. E end, on mudflats near river Lyonia †ligustrina (L.) DC.—maleberry. (Xolisma shore and rock outcrop. I. ligustrina (L.) Britton). (Killip & Blake 1935). Sedum ternatum Michx.—three-leaved stonecrop, Rhododendron †periclymenoides (Michx.) Shin- wild stonecrop. (7) W.J. Kress & M. Butts 04- ners—pinxter-flower, pink azalea, pink-honey- 7562, 15 Jul 2004. Ridge above floodplain, on suckle. (Azalea nudiflora Pursh, R. nudiflorum rock. I. (L.) Torr.) (3) M. Beyersdorfer 91, 10 May 1983. Mainland, path to ferry dock. Vaccinium †corymbosum L.—highbush blueberry, CUCURBITACEAE (Gourd Family) swamp blueberry. (V. atrococcum (A. Gray) A. Echinocystis lobata (Michx.) Torr. & A. Gray—wild Heller). (2) E.P. Killip 31200, 3 Jun 1934. cucumber, prickly-cucumber, wild balsam-apple. Mainland, near Northwest Swamp. (Micrampelis lobata (Michx.) Greene). (1) A.S. pallidum Aiton—lowbush blueberry, late lowbush Hitchcock 15702, 9 Sep 1917. blueberry, hillside blueberry, upland blueberry.

(V. vacillans Kalm ex Torr.) (4) E.C. Leonard Leonard & N. Hotchkiss 3295, 25 Sep 1960. & N. Hotchkiss 3569, 9 May 1961. High Upper Gap, rock outcrops. Knoll. I. Amphicarpaea bracteata (L.) Fernald—hog-peanut. stamineum L.—deerberry, squaw-huckleberry. (A. pitcheri T. & G., Falcata comosa (L.) (Polycodium stamineum Small). (10) W.J. Kress Kuntze, F. pitcheri (T. & G.) Kuntze). (6) M. & M. Butts 04-7563, 15 Jul 2004. Ridge above Beyersdorfer 244, 12 Sep 1982. Near Fern Val- floodplain, on rock. I. ley. I. Apios americana Medik.—common groundnut, wild EUPHORBIACEAE (Spurge Family) bean. (Glycine apios L.) (Killip & Blake 1935, Acalypha gracilens A. Gray—slender three-seeded- ‘‘probably extinct.’’) mercury, short-stalk copperleaf. (5) E.C. Leon- Astragalus canadensis L.—Canada milk-vetch, rat- ard & N. Hotchkiss 3245, 27 Sep 1960. Rock tle-vetch. (Astragalus carolinianus L.) (2) E.P. of Gibraltar. Killip 32928, 23 Jun 1940. South of West Knoll, ϩrhomboidea Raf.—common three-seeded-mer- just below where trail bends toward river. cury, rhombic copperleaf. (6) E.F. Wells, R.L. Baptisia australis (L.) R. Br.—blue false indigo. Brown & V.S. Murthy 4389, 30 Jul 1997. Flood- (Killip & Blake 1935, ‘‘sporadic’’). plain. Comments: Early specimen of P.C. Stan- †tinctoria (L.) R. Br. ex W. T. Aiton—wild indigo, dley (12524, 1915) was misidentified as A. vir- yellow wild indigo, rattleweed. (1) E.P. Killip ginica. M. 31048, 25 Jun 1933. Mainland, between main virginica L.—Virginia three-seeded-mercury, Vir- trail and Stewart Farm. ginia copperleaf. (A. digyneia Raf.) (7) E.C. Cercis canadensis L.—redbud, Judas-tree. (9) W.J. Leonard & N. Hotchkiss 3383, 27 Sep 1960. Kress & M. Butts 04-7509, 8 Jun 2004. Flood- Poachers Landing, sandy alluvial riverbank. plain near NW point. I. Euphorbia commutata Engelm.—wood spurge, Chamaecrista fasciculata (Michx.) Greene—par- tinted spurge. (Tithymalus commutatus (En- tridge-pea. (Cassia fasciculata Michx.) (5) E.C. gelm.) Klotzsch & Garcke.) (8) M. Beyersdorfer Leonard & N. Hotchkiss 3308, 27 Sep 1960. 13-84, 21 May 1984. West end river side, just Upper Gap, between outcropping rocks. east of Rock of Gibraltar. ‘‘Party spot.’’ nictitans (L.) Moench—sensitive-pea, small-flow- corollata L.—flowering spurge. (Tithymalopsis ered partridge-pea. (Cassia nictitans L.) (3) E.P. paniculata (Ell.) Small). (9) A.S. Hitchcock Killip 31840, 5 Jul 1936. ‘‘Barrens’’ along chan- 15632, 29 Jul 1917. nel. maculata L.—spotted spurge, milk-purslane. Clitoria mariana L.—butterfly-pea. (4) E.P. Killip (Chamaesyce maculata (L.) Small, C. supina 13684, 26 Jul 1931. Near Cactus Rock. (Raf.) Moldenke, E. nutans Lag., misapplied., E. Crotalaria sagittalis L.—rattlebox. (1) E.P. Killip supina Raf.) (6) S.G. Shetler, E.F. Wells & R.J. 32155, 1 Aug 1937. ‘‘Barrens’’ near new ferry Soreng 2004.41, 30 Oct 2004. West end, sandy posts. muddy shores of river. I. Desmodium canescens (L.) DC.—hoary tick-trefoil. nutans Lag.—eyebane. (Chamaesyce hypericifolia (Meibomia canescens (L.) Kuntze). (3) E.P. Kil- (L.) Millsp., misapplied, C. maculata L., mis- lip 32225, 19 Sep 1937. Path of flood near upper applied, C. nutans (Lag.) Small, C. preslii end; edge of woods toward north end. (Guss.) Arthur, E. hypericifolia L., misapplied, cuspidatum (Muhl. ex Willd.) DC. ex Loudon— E. maculata L., misapplied, E. preslii Guss.) (8) big tick-trefoil. (D. bracteosum (Michx.) DC., W.J. Kress & N.A. Bourg 04-7621, 5 Sep 2004. Meibomia bracteosa (Michx.) Kuntze). (3) N. E end, on rock outcrop. Comments: Originally Hotchkiss & E.C. Leonard 3211, 27 Sep 1960 identified as E. maculata. I. [2 sheets]. Phyllanthus caroliniensis Walter—Carolina leaf- glabellum (Michx.) DC.—(D. dillenii Darl., in flower. (5) S.G. Shetler & S.S. Orli 2004.27, 3 large part, D. perplexum B.G. Schub., Meibomia Aug 2004. Mainland, sandy bank of channel dillenii (Darl.) Kuntze, in large part, M. glabella near Crossing Rocks. I. (Michx.) Kuntze). (11) W.J. Kress & N.A. Bourg 04-7624, 5 Sep 2004. E end, sandy river shore FABACEAE (Legume Family) next to trail before reaching rock outcrops. I. ALBIZIA ϩJULIBRISSIN Durazz.—mimosa, silk-tree. nudiflorum (L.) DC.—naked-flowered tick-trefoil. Comments: Small seedling observed by Shetler (Meibomia nudiflora (L.) Kuntze). (3) E.P. Kil- and Wells in woods along channel NE of Cabin lip 31069, 6 Aug 1933. Mainland, west of main Hill on 21 July 2004. I. trail. Amorpha ϩfruticosa L.—false indigo. (1) E.C. paniculatum (L.) DC.—panicled tick-trefoil.

(Meibomia paniculata (L.) Kuntze). (3) E.P. northern wild senna. (Cassia hebecarpa Fernald, Killip 40171, 18 Sep 1949. Gap at upper end. C. marilandica L., misapplied, C. nictitans var. Galactia volubilis (L.) Britton—hairy milk-pea. (4) hebecarpa Fernald). (6) M. Beyersdorfer 187, E.C. Leonard & N. Hotchkiss 3554, 9 May 15 Aug 1982. Mainland side of Crossing Rocks 1961. Upper Gap, rock crevice. Comments: T.H. at Island’s east end. Kearney 1 (19 Aug 1903) and C.F. Wheeler s.n. Strophostyles umbellata (Muhl. ex Willd.) Brit- (21 Sep 1903) apparently not seen by Killip & ton—perennial wooly-bean. (1) E.P. Killip Blake (1935). 32630, 14 Aug 1938. Along trail just west of GLEDITSIA TRIACANTHOS L.—honey-locust. (4) W.J. sand bank above Cactus Rock [2 sheets]. Kress & M. Butts 04-7552, 1 Jul 2004. Along Tephrosia †virginiana (L.) Pers.—goat’s-rue, cat- beach near SW point. I. gut. (Cracca virginiana L.) (2) E.P. Killip Lespedeza capitata Michx.—bush-clover, round- 31335, 29 Sep 1934. Mainland, west of main headed bush-clover. (2) E.P. Killip 36641, 13 trail, toward Northwest Swamp. Comments: Not Sep 1942. East end. among species starred (*) by Killip & Blake intermedia (S. Watson) Britton—(L. frutescens (1935) as restricted to Mainland, even though (L.) Elliott, misapplied). (2) E.P. Killip 31121, both specimens came from Mainland. 17 Sep 1933. Near cabin. Trifolium ARVENSE L.—rabbit-foot clover. (2) E.P. procumbens Michx.—trailing bush-clover. (3) Killip 31848, 5 Jul 1936. ‘‘Barrens’’ along chan- E.C. Leonard & N. Hotchkiss 3223, 27 Sep nel. 1960. High Knoll. CAMPESTRE Schreb.—low hop clover, pinnate hop repens (L.) Barton—creeping bush-clover. (7) N. clover. (T. procumbens L. misapplied). (1) E.P. Hotchkiss & E.C. Leonard 3558, 9 May 1961. Killip & C.V. Morton 36629, 12 Jul 1942. Cabin Upper Gap [2 sheets]. Hill, west slope near top. STIPULACEA Maxim.—Korean clover, Korean les- HYBRIDUM L.—alsike clover. (2) E.C. Leonard & pedeza. (Kummerowia stipulacea (Maxim.) Ma- N. Hotchkiss 3588, 9 May 1961. River trail. kino). (6) E.C. Leonard & N. Hotchkiss 3564, 9 PRATENSE L.—red clover. (2) E.P. Killip 31885, 12 May 1961. River trail w[est] [3 sheets]. Jul 1936. ‘‘Barrens’’ along channel. W. ϩSTRIATA (Thunb.) Hook. & Arn.—Japanese clo- REPENS L.—white clover. (3) M. Beyersdorfer 103, ver, Japanese bush-clover, Japanese lespedeza. 18 May 1983. Crossing Rocks. W. (Kummerowia striata (Thunb.) Schindl.) (2) Vicia carolinianum Walter—pale vetch, wild vetch, E.F. Wells, R.L. Brown & V.S. Murthy 4441, 31 wood vetch. (1) A.S. Hitchcock 12477, 2 May Aug 1997. Comments: A.S. Hitchcock 15836 1915. (16 Sep 1917) apparently overlooked by Killip SATIVA L.—common vetch, spring vetch. (Includ- & Blake in 1935 and 1953. ing V. angustifolia L.) (1) E.P. Killip 31180, 30 violacea (L.) Pers.—violet bush-clover. (11) E.C. May 1934. Mainland, Fisher Garden. Leonard & N. Hotchkiss 3316, 27 Sep 1960. Upper Gap, between outcropping rocks [2 FAGACEAE (Beech Family) sheets]. virginica (L.) Britton—Virginia bush-clover, slen- Castanea dentata (Marshall) Borkh.—chestnut, der bush-clover. (4) S.G. Shetler & E.R. Shetler American chestnut. (1) A.K. Fisher s.n., 14 Oct 2004.34, 11 Oct 2004. Mainland, sandy bank at 1934. Mainland. Comments: ‘‘Extinct on both Rock Crossing. Comments: Specimen over- Island and mainland; preserved specimen from looked in 1935 (Killip & Blake 1953). mainland only’’ (Killip & Blake 1935). MEDICAGO LUPULINA L.—black medick. (2) E.P. Kil- pumila Mill.—chinquapin. Comments: Killip & lip 31843, 5 Jul 1936. ‘‘Barrens’’ along channel. Blake included it in their 1935 list based on ob- SATIVA L.—alfalfa. (1) E.P. Killip 32622, 3 Jul servations but added, ‘‘Extinct, at least on Is- 1938. ‘‘Barrens’’ near lower of new ferry posts. land.’’ MELILOTUS ALBUS Medik.—white sweet-clover. (6) Fagus grandifolia Ehrh.—beech, American beech. W.J. Kress & M. Butts 04-7544, 23 Jun 2004. (2) M. Beyersdorfer 54, 28 Apr 1983. Mainland, SW Point (rocks). I. path to ferry dock, just below Lock 12. M. OFFICINALIS (L.) Lam.—yellow sweet-clover. (1) Quercus alba L.—white oak. (Q. ϫsaulei C.K. E.P. Killip 32114, 31 May 1937. ‘‘Barrens’’ Schneid.) (4) M. Beyersdorfer 104, 23 Jun near upper of new ferry posts. 1982. I. Robinia pseudoacacia L.—black locust. (5) M. Be- †bicolor Willd.—swamp white oak. (1) E.P. Killip yersdorfer 11-84, 21 May 1984. Rock of Gi- 31342, 3 Nov 1934. [Mainland], near upper braltar table. I. gate. Only tree of this species on property. Senna hebecarpa (Fernald) H.S. Irwin & Barneby— †falcata Michx.—Spanish oak, southern red oak.

(Q. rubra L., misapplied). (1) E.P. Killip 31206, GERANIACEAE (Geranium Family) 3 Jun 1934. Mainland, woods east of Fisher Gar- Geranium carolinianum L.—Carolina cranesbill. den. Comments: Only known from Mainland, (2) A.S. Hitchcock 12703, 31 May 1915. but not so indicated by Killip & Blake maculatum L.—wild geranium, wild cranesbill. (1935). M. (7) M. Beyersdorfer 32, 25 Apr 1982. Gap, to- †marilandica (L.) Mu¨nchh.—blackjack oak. (1) ward channel. W. E.P. Killip 31207, 3 Jun 1934. Mainland, woods east of Fisher Garden. HALORAGACEAE (Water-milfoil Family) montana Willd.—chestnut oak, mountain chestnut oak, rock chestnut oak. (Q. prinus L., in part). ϩMyriophyllum SPICATUM L.—European water- (10) W.J. Kress & M. Butts 04-7489, 20 May milfoil. (M. exalbescens Fernald, misapplied). 2004. Ridge above central plain, mid-island. I. (1) M. Beyersdorfer 350B, 10 Oct 1982. Main- muhlenbergii Engelm.—yellow oak, chestnut oak, land, C&O Canal. Comments: Mixed with a col- chinquapin oak. (3) E.P. Killip 32660, 9 Jul lection of Ceratophyllum echinatum A. Gray (as 1939, as Q. prinus. Upper Gap, edge of woods, C. demersum L.) (Beyersdorfer 350A). just north of laurel patch. Comments: Killip specimen re-determined as this species by A.T. HAMAMELIDACEAE (Witch-hazel Family) Whittemore (Apr 2003). M. Hamamelis virginiana L.—witch-hazel. (3) M. palustris Mu¨nchh.—pin oak. (1) T.H. Kearney 57, Beyersdorfer 70, May 1982. Top of Cabin Hill, 19 Aug 1903. dry cliff side. I. phellos L.—willow oak. (Q. ϫheterophylla F. Michx.) ‘‘One tree formerly grew on Island’’ HYDROPHYLLACEAE (Waterleaf Family) (Killip & Blake 1935). Comments: Under Q. heterophylla, they also reported one tree on the Ellisia nyctelea L.—water-pod, ellisia. (Nyctelea am- Mainland, presumably still growing at the time. bigua (Nutt.) Standl.) (5) E.C. Leonard & N. rubra L.—northern red oak. (Q. borealis F. Hotchkiss 3504, 9 May 1961. East end near Michx., Q. maxima (Marshall) Ashe). (16) W.J. channel. Kress & M. Butts 04-7524, 17 Jun 2004. Cabin Hydrophyllum canadense L.—broad-leaved water- Hill, south side of cabin. I. leaf, maple-leaved waterleaf. (13) W.J. Kress & stellata Wangenh.—post oak. (3) A.S. Hitchcock M. Butts 04-7502, 27 May 2004. Mid-island 12952, 1 Jul 1917. M. near north shore. I. virginianum L.—Virginia waterleaf, eastern wa- FUMARIACEAE (Fumitory Family) terleaf. (5) M. Beyersdorfer 69, 10 May 1983. Base of Cabin Hill, along path to east end. Corydalis flavula (Raf.) DC—yellow fumewort, M, W. pale corydalis, yellow corydalis. (Capnoides fla- Phacelia dubia (L.) Trel.—small-flowered phacelia, vulum (Raf.) Kuntze). (6) M. Beyersdorfer 24, Appalachian phacelia. (12) W.J. Kress & M. 14 Apr 1983. Cactus Rock. I. Butts 04-7458, 11 May 2004. Cactus Rock. I. Dicentra canadensis (Goldie) Walp.—squirrel-corn. purshii Buckley—Miami-mist, Pursh’s phacelia. (Bicuculla (Bikukulla) canadensis (Goldie) (13) M. Beyersdorfer 66, 2 May 1983. Cactus Millsp.) (13) E.F. Wells, R.L. Brown & V.S. Rock. Murthy 4884, 27 Apr 1998. Floodplain. I. ranunculacea (Nutt.) Constance—Coville’s pha- cucullaria (L.) Bernh.—Dutchman’s-breeches. celia, buttercup phacelia. (P. covillei S. Watson (Bicuculla (Bikukulla) cucullaria (L.) Millsp.) (Isotype: F.V. Coville s.n., 1889, Larkspur Is- (5) M. Beyersdorfer 4, 4 Apr 1982. ‘‘Gap’’ area land [Montgomery Co., MD], US42482)). (16) of Island. S.G. Shetler & 2004.3, 1 May 2004. Slope in front of cabin. Comments: See T.I. Chuang & L. Constance (1977) and Sewell (2003) con- GENTIANACEAE (Gentian Family) cerning status of P. covillei as a separate species. I. Gentiana villosa L.—striped gentian, Sampson’s- snakeroot. (1) T.H. Kearney 179, 30 Aug 1903. HYPERICACEAE (St. John’s-wort Family) Obolaria virginica L.—pennywort. (Killip & Blake 1935). Hypericum gentianoides (L.) Britton, Sterns & Pog- Sabatia angularis (L.) Pursh—common marsh-pink, genb.—orange-grass, pineweed. (Sarothra gen- rose-pink. (3) E.P. Killip 32628, 31 Jul 1938. tianoides L.) (3) E.P. Killip 31917, 2 Aug 1936. Gap at upper end, toward northwest corner. ‘‘Barrens’’ near entrance to channel.

hypericoides (L.) Crantz—St. Andrew’s-cross. royal. (3) E.P. Killip 32634, 21 Aug 1938. Gap (Ascyrum hypericoides L.) (2) A.S. Hitchcock at upper end. 15767, 9 Sep 1917. I. LAMIUM ϩAMPLEXICAULE L.—henbit. (1) P.C. Stan- mutilum L.—small-flowered St. John’s-wort, dley 11284, 18 Apr 1915. Comments: Standley’s dwarf St. John’s-wort. (H. majus (Gray) Britt.) specimen overlooked by Killip & Blake (1935, (5) E.F. Wells, R.L. Brown & V.S. Murthy 4372, 1953). 30 Jul 1997. Floodplain. I. PURPUREUM L.—purple dead-nettle, red dead-net- †PERFORATUM L.—common St. John’s-wort. (1) tle. (L. hybridum Vill., misapplied). (7) W.J. E.P. Killip 31064, 2 Jul 1933. [Mainland], Stew- Kress & M. Butts 04-7476, 13 May 2004. art Farm. Beach, SW end. I. prolificum L.—shrubby St. John’s-wort. (7) W.J. LEONURUS CARDIACA L.—motherwort. (1) E.P. Killip Kress & M. Butts 04-7547, 23 Jun 2004. SW 31276, 4 Aug 1934. Cabin Hill near fireplace. Point (rocks). I. Lycopus americanus Muhl.—American water-hore- punctatum Lam.—dotted St. John’s-wort, spotted hound, cut-leaved water-horehound. (5) S. Wiser St. John’s-wort. (H. denticulatum Walter, mis- & C. Van Metre 49, 11 Sep 1986. West end, to applied). (8) W.J. Kress & M. Butts 04-7519, 17 the west of Cactus Rock, rocky ‘‘islands’’ di- Jun 2004. Cabin Hill near picnic tables. I. rectly offshore. W. rubellus Moench—stalked water-horehound. (1) JUGLANDACEAE (Walnut Family) E.P. Killip 32156, 1 Aug 1937. ‘‘Barrens’’ near new ferry posts. Carya cordiformis (Wangenh.) K. Koch—bitternut, ϩϫsherardii E.S. Steele (ϭ Lycopus virginicus ϫ bitternut hickory. (Hicoria cordiformis (Wan- L. uniflorus)—Sherard’s water-horehound. (2) genh.) Britton). (16) W.J. Kress & M. Butts 04- T.H. Kearney 119, 23 Aug 1903. 7548, 1 Jul 2004. Cactus Rock. I. virginicus L.—bugleweed, Virginia bugleweed, glabra (Mill.) Sweet—pignut, pignut hickory, Virginia water-horehound. (8) S.G. Shetler & sweet pignut, false shagbark. (C. ovalis (Wan- S.S. Orli 2004.29, 3 Aug 2004. Mainland, genh.) Sarg., Hicoria glabra (Mill.) Britton, H. Northwest Swamp [2 sheets]. M. microcarpa (Nutt.) Britton). (16) W.J. Kress & Mentha arvensis L.—field mint, wild mint. (M. can- M. Butts 04-7520, 17 Jun 2004. Cabin Hill near adensis L.) (3) E.P. Killip 31931, 22 Aug 1936. picnic tables. I. ‘‘Barrens’’ along channel toward lower end. ovata (Mill.) K. Koch—shagbark hickory. (Hicor- ϫGRACILIS Sole (ϭ M. arvensis ϫ M. spicata)— ia ovata (Mill.) Britton). (Killip & Blake 1935). small-leaved mint, red mint, Scotch mint. (M. Comments: Record possibly based on trans- cardiaca J. Gerard ex Baker, M. ϫ gentilis L., planting to Mainland reported by McAtee (1930, misapplied). (1) E.P. Killip 32170, 3 Aug 1937. p. 54). The one large, extant tree in 2004 ap- On rocks toward north end of upper flood path. peared to have been a graft. M. Monarda clinopodia L.—basil-balm, basil bee- Juglans cinerea L.—butternut, white walnut. (Killip balm. (4) M. Beyersdorfer 130, 4 Jul 1982. & Blake 1935). Channel side of Gap. nigra L.—black walnut. (5) E.F. Wells, R.L. NEPETA CATARIA L.—catnip. (3) E.F. Wells, R.L. Brown & V.S. Murthy 4392, 30 Jul 1997. Flood- Brown & V.S. Murthy 4371, 30 Jul 1997. Flood- plain. I. plain. PERILLA FRUTESCENS (L.) Britton—perilla, beef- LAMIACEAE (Mint Family) steak-plant, perilla-mint. (5) E.F. Wells, R.L. Brown & V.S. Murthy 4479, 20 Sep 1997. Agastache nepetoides (L.) Kuntze—yellow giant- Floodplain. I. hyssop, catnip giant-hyssop. (3) S.F. Blake s.n., Physostegia virginiana (L.) Benth.—obedient-plant, 19 Oct 1933. Front of cabin. obedience. (Dracocephalum virginianum L., P. Collinsonia canadensis L.—richweed, horse-balm, speciosa (Sweet) Sweet) (1) E.P. Killip 32142, citronella. (4) W.J. Kress & M. Butts 04-7571, 4 Jul 1937. Lower end, toward river. 22 Jul 2004. E end, near shore of river. I. Prunella vulgaris L.—heal-all, selfheal. (2) E.P. Kil- Cunila origanoides (L.) Britton—dittany. (4) M. Be- lip 31070, 13 Aug 1933. Near boat landing. M. yersdorfer 259, 12 Sep 1982. Cabin Hill. I. Pycnanthemum †incanum (L.) Michx.—hoary GLECHOMA HEDERACEA L.—gill-over-the-ground, mountain-mint. (Koellia incana (L.) Kuntze). ground-ivy. (9) W.J. Kress & M. Butts 04-7447, (1) E.P. Killip 13234, 14 Jul 1928. [Mainland], 6 May 2004. Along path halfway between ter- west side of Stewart Farm. race and river. I. tenuifolium Schrad.—narrow-leaved mountain- Hedeoma pulegioides (L.) Pers.—American penny- mint. (Koellia flexuosa (Walter) MacMill., mis-

applied, P. flexuosum (Walter) Britton, Sterns & LIMNANTHACEAE (Meadow-foam Family) Poggenb., misapplied). (3) E.P. Killip 32621, 26 Floerkea proserpinacoides Jun 1938. At base of Sycamore at river end of Willd.—false mermaid. P.C. Standley 13115, Gap. (5) 7 May 1916. I. ϩverticillatum (Michx.) Pers.—verticillate mountain-mint. (Koellia verticillata (Michx.) Kuntze). LINACEAE (Flax Family) (2 sheets of 1 collection) E.P. Killip 41367, 17 Linum medium (Planch.) Britton—common yellow Aug 1951. Comments: Originally identified as flax, stiff yellow flax. (1) S.F. Blake s.n., 26 Jul P. virginianum (L.) T. Durand & B.D. Jacks. ex 1924. Cabin Hill, west slope. B.L. Rob. & Fernald and included as such in Killip & Blake (1953). LOBELIACEAE (Lobelia Family) Salvia lyrata L.—lyre-leaved sage. (6) M. Beyers- dorfer s.n., 19 Oct 1984. Between Rock of Gi- Lobelia cardinalis L.—cardinal-flower. (3) M. Be- braltar and Cactus Rock, just east of rock out- yersdorfer 208, 26 Aug 1982. Channel bank at crop in river. W. west end by stream that enters from under Satureja CALAMINTHA (L.) Scheele—basil-thyme. bridge. M, W. (Clinopodium nepeta (L.) Kuntze, S. nepeta (L.) inflata L.—Indian-tobacco. (4) E.F. Wells, R.L. Scheele). (1) S.F. Blake s.n., 20 Oct 1936. Waste Brown & V.S. Murthy 4539, 21 Sep 1997. weedy ground formed by 1936 flood. Floodplain. vulgaris (L.) Fritsch.—basil, wild basil. (Clino- siphilitica L.—great lobelia, great blue lobelia, podium vulgare L.) (3) A.S. Hitchcock 15628, blue cardinal-flower. (5) E.F. Wells, R.L. Brown 29 Jul 1917. & V.S. Murthy 4523, 21 Sep 1997. Floodplain. Scutellaria elliptica Muhl. ex Spreng.—hairy skullcap. (S. ovalifolia Pers.) (6) W.J. Kress & M. LYTHRACEAE (Loosestrife Family) Butts 04-7510, 8 Jun 2004. Slope below cabin ϩ (west side). I. Ammannia coccinea Rottb.—tooth-cup. (7) E.F. ϩintegrifolia L.—large-flowered skullcap, hyssop Wells, R.L. Brown & V.S. Murthy 4435, 31 Aug skullcap. (2) E.P. Killip 32610, 26 Jun 1938. 1997. Floodplain. ‘‘Barrens’’ just north of sand bank toward east Cuphea viscosissima Jacq.—blue waxweed, clammy end. Comments: Apparently both P.C. Standley cuphea, tarweed. (C. petiolata (L.) Koehne, 11768 (1915) and Killip 32610 (1938) were Parsonsia petiolata (L.) Rusby). (3) E.P. Killip overlooked by Killip & Blake in compiling their 13478, 21 Sep 1930. West end, sandbar. checklists (1935, 1953). Lythrum alatum Pursh—winged loosestrife, wing- lateriflora L.—mad-dog skullcap. (S. epilobiifolia angled loosestrife. (2) E.P. Killip 32144, 6 Jul A. Ham., misapplied by Killip & Blake in 1937. Lower end, close to river. 1935). (3) E.C. Leonard & N. Hotchkiss 3543, Rotala ramosior (L.) Koehne—tooth-cup. (2) E.P. 9 May 1961. Near base of Outlook Rock. Killip 31923, 9 Aug 1936. Halfway between fer- Stachys ϩtenuifolia Willd.—common hedge-nettle, ry landing and upper end, marshy soil at edge smooth hedge-nettle. (1) E.P. Killip 32171, 3 of pool. Aug 1937. Flood path near upper end. Com- ments: Treated as S. aspera Michx. by Killip & MAGNOLIACEAE (Magnolia Family) Blake in 1953. Liriodendron tulipifera L.—tulip-tree, yellow-pop- Teucrium canadense L.—American germander, lar, tulip-poplar. (3) W.J. Kress & M. Butts 04- American wood-sage. (7) W.J. Kress & M. Butts 7459, 13 May 2004. Terrace. I. 04-7527, 23 Jun 2004. Near E point. I. Magnolia †virginiana L.—swamp magnolia, sweet- Trichostema dichotomum L.—blue-curls. (2) A.S. bay, swamp-bay. (1) M. Beyersdorfer 112, 20 Hitchcock 15814, 16 Sep 1917. Jun 1982. [Mainland], border of Frog Pond— opposite Taxodium. Comments: Perhaps the LAURACEAE (Laurel Family) planted one (McAtee 1930, p. 54).

Lindera benzoin (L.) Blume—spicebush. (Benzoin MALVACEAE (Mallow Family) aestivale (L.) Nees). (7) W.J. Kress & M. Butts 04-7443, 6 May 2004. Along path directly be- ABUTILON THEOPHRASTI Medik.—velvet-leaf, Indi- low (ENE) terrace. I. an-mallow. (4) E.F. Wells, R.L. Brown & V.S. Sassafras albidum (Nutt.) Nees—sassafras, white Murthy 5165, 12 Jun 1997. Floodplain. I. sassafras. (S. variifolium (Salisb.) Kuntze.) (2) Hibiscus laevis All.—halberd-leaved rose-mallow, M. Beyersdorfer 202, 22 Aug 1982. smooth rose-mallow. (H. militaris Cav.) (8) W.J.

Kress & M. Butts 04-7559, 15 Jul 2004. W Fraxinus americana L.—white ash. (F. biltmoreana point, rocks near I-495 bridge. I. Beadle). (16) E.C. Leonard & N. Hotchkiss moscheutos L.—rose-mallow, swamp rose-mal- 3572, 9 May 1961. Cabin Hill [3 sheets]. I. low. (H. palustris L.) (1) A.H. Hitchcock 15729, pennsylvanica Marshall—red ash, green ash. (F. 9 Sep 1917. M, W. lanceolata Borkh.) (13) E.F. Wells, E.F. & R.L. ϩTRIONUM L.—flower-of-an-hour. (2) E.P. Killip Brown & V.S. Murthy 4411, 25 Jul 1997. Flood- 43333, 12 Aug 1953 [2 sheets]. East sandbar. plain. I. MALVA NEGLECTA Wallr.—common mallow, cheeses. LIGUSTRUM ϩ†OBTUSIFOLIUM Siebold & Zucc.— (M. rotundifolia L., misapplied). (1) E.P. Killip border privet. (2) S.G. Shetler & S.S. Orli & J.R. Swallen 31906, 19 Jul 1936. ‘‘Barrens’’ 2004.26, 3 Aug 2004. Mainland, in woods near east of new ferry posts. ponds. Comments: A sterile specimen of Ligus- Sida hermaphrodita (L.) Rusby—Virginia-mallow, trum has been collected on the Island (W.J. Virginia sida. (5) E.P. Killip 32626, 24 Jul 1938. Kress & M. Butts 04-7507, 8 Jun 2004), which Along side of river just above water gauge. might be this species. I. spinosa L.—false mallow, prickly-mallow, prickly sida. (S. angustifolia Lam., misapplied). (6) W.J. ONAGRACEAE (Evening-primrose Family) Kress & N.A. Bourg 04-7618, 05 Sep 2004. E Circaea lutetiana L.—common enchanter’s-night- end, on mudflats near river shore, channel shade. (C. latifolia Hill, C. quadrisulcata (Max- side. I. im.) Franch. & Savigny). (2) A.S. Hitchcock MENISPERMACEAE (Moonseed Family) 12969, 1 Jul 1917. Epilobium coloratum Biehler—eastern willow-herb, Menispermum canadense L.—moonseed. (7) E.F. purple-leaved willow-herb. (1) A.S. Hitchcock Wells, R.L. Brown & V.S. Murthy 5162, 12 Jun 15704, 9 Sep 1917. 1997. Floodplain. I. Gaura biennis L.—gaura, biennial gaura. (3) E.P. Killip 13320, 9 Sep 1928. [Mainland], Stewart MOLLUGINACEAE (Carpetweed Family) Farm. Mollugo verticillata L.—carpetweed. (5) W.J. Kress Ludwigia alternifolia L.—seedbox, square-pod wa- & M. Butts 04-7445, 6 May 2004. Along path ter-primrose. (5) E.F. Wells, R.L. Brown & V.S. directly below (ENE) terrace. I. Murthy 4406, 30 Jul 1997. Floodplain. M. palustris (L.) Elliott—common water-purslane, MONOTROPACEAE (Indian-pipe Family) marsh-purslane. (Isnardia palustris L.) (7) M. Beyersdorfer 294, 25 Sep 1982. East end, Cross- Monotropa uniflora L.—Indian-pipe. (2) E.P. Killip ing Rocks, rocky crevices. M, W. & M.K. Brady 32655, 3 Jul 1939. Just beneath ϩPEPLOIDES (Kunth) P.H. Raven—creeping prim- one of lower stone steps toward Landing Rock. rose-willow, creeping water-primrose. (1) E.F. Wells, R.L. Brown & V.S. Murthy 4866, MORACEAE (Mulberry Family) 31 Aug 1997. Floodplain. MACLURA POMIFERA (Raf.) C.K. Schneid.—osage- Oenothera biennis L.—common evening-primrose. orange. (Toxylon pomiferum Raf. ex Sarg.) (Kil- (O. gauroides Hornem.) (10) E.F. Wells, R.L. lip & Blake 1935). I. Brown & V.S. Murthy 5182, 12 Jun 1997. Morus ALBA L.—white mulberry, silkworm mulber- Floodplain. M. ry. (2) N. Hotchkiss & E.C. Leonard 3357, 27 †fruticosa L.—sundrops. (Kneiffia fruticosa (L.) Sep 1960. Between boat landing and Poachers Raim., K. tetragona (Roth) Pennell, O. tetra- Landing [2 sheets]. I. gona Roth). (1) E.P. Killip 31053, 25 Jun 1933. rubra L.—red mulberry. (3) A.S. Hitchcock [Mainland], Stewart Farm. 12663, 22 May 1915. laciniata Hill—cut-leaved evening-primrose. (Rai- mannia laciniata (Hill) Rose). (2) E.P. Killip NYSSACEAE (Black-gum Family) 31891, 12 Jul 1936. ‘‘Barrens’’ near ferry land- Nyssa sylvatica Marshall—black-gum, sour-gum, ing. pepperidge, black tupelo. (2) E.P. Killip 31261, 22 Jul 1934. Mainland, Northwest Swamp. W. OROBANCHACEAE (Broom-rape Family) Conopholis ϩamericana (L.f.) Wallr.—cancer-root, OLEACEAE (Olive Family) squaw-root. (1) M. Beyersdorfer 73, 10 May Chionanthus virginicus L.—fringe-tree, old-man’s- 1983. Cabin Hill slope that leads into valley in beard. (10) W.J. Kress & M. Butts 04-7462, 13 front of cabin. May 2004. Near Cactus Rock. I. Orobanche uniflora L.—one-flowered cancer-root,

cancer-root, one-flowered broom-rape. (Thalesia PLANTAGINACEAE (Plantain Family) uniflora (L.) Britton). (5) M. Beyersdorfer 105, Plantago ARISTATA Michx.—bracted plantain, buck- 18 May 1983. Path to west end just past Gap, horn, bottle-brush plantain. (1) E.P. Killip river side—‘‘party spot.’’ I. 31890, 12 Jul 1936. ‘‘Barrens’’ just below ferry OXALIDACEAE (Wood-sorrel Family) landing. LANCEOLATA L.—English plantain, narrow-leaved ϩ Oxalis CORNICULATA L.—creeping wood-sorrel. plantain, ribgrass, buckhorn. (3) E.P. Killip (Xanthoxalis corniculata (L.) Small). (2) A.S. 31867, 5 Jul 1936. ‘‘Barrens’’ along channel. Hitchcock 12571, 9 May 1915. Comments: This rugelii Decne.—common plantain, broad-leaved specimen and one collected by P.C. Standley plantain, American plantain. (5) E.F. Wells, R.L. (11485) on the same day and probably at the Brown & V.S. Murthy 4529, 21 Sep 1997. same time and place were misidentified. Floodplain. dillenii Jacq.—southern wood-sorrel, slender virginica L.—dwarf plantain, hoary plantain. (1) wood-sorrel. (O. filipes Small, O. florida Salisb., S.F. Blake s.n., 26 Jul 1924. O. stricta L., misapplied, Xanthoxalis filipes Small, X. stricta L., misapplied). (9) W.J. Kress PLATANACEAE (Plane-tree Family) & M. Butts 04-7455, 11 May 2004. Cabin Hill, under picnic tables. I. Platanus occidentalis L.—sycamore, American grandis Small—great wood-sorrel, big wood-sor- plane-tree. (7) W.J. Kress & M. Butts 04-7475, rel. (Xanthoxalis grandis (Small) Small). (8) 13 May 2004. Beach, SW end. I. P.C. Standley 11641, 6 Jun 1915. Damp woods. stricta L.—common wood-sorrel, upright wood- POLEMONIACEAE (Phlox Family) sorrel. (O. cymosa Small, O. europaea Jord., Phlox divaricata L.—wild blue phlox, forest phlox. Xanthoxalis cymosa (Small) Small, X. stricta (11) W.J. Kress & M. Butts 04-7436, 6 May (L.) Small). (17) S.G. Shetler & E.F. Wells 2004. Terrace. I. 2004.17, 21 Jul 2004. Mainland, edge of woods paniculata L.—summer phlox, garden phlox, fall along trail near Crossing Rocks. I. phlox, perennial phlox. (3) S. Wiser 12, 8 Aug violacea L.—violet wood-sorrel. (Ionoxalis viola- 1986. West end, floodplain, towards channel. cea (L.) Small). (5) W.J. Kress & M. Butts 04- †subulata L.—moss-pink, moss phlox. (Killip & 7463, 13 May 2004. Near Cactus Rock. I. Blake 1935, ‘‘extinct’’). PAPAVERACEAE (Poppy Family) POLYGALACEAE (Milkwort Family) CHELIDONIUM MAJUS L.—celandine, greater celandine. (4) M. Beyersdorfer 1-84, 11 May 1984. Polygala polygama Walter—racemed milkwort. (3) Below Rock of Gibraltar, sandy alluvial soil. E.P. Killip 40536, 3 Jul 1950. West Knoll, Papaver DUBIUM L.—orange poppy, smooth-fruited northwest corner. poppy, long-headed poppy. (2) E.P. Killip verticillata L.—whorled milkwort. (1) E.P. Killip 31027, 4 Jun 1933. South of West Knoll, open & F. Drouet 36517, 24 Jul 1941. Upper Gap, grassland. toward west side. Sanguinaria canadensis L.—bloodroot. (6) M. Bey- ersdorfer 11, 25 Mar 1983. Gap, channel POLYGONACEAE (Smartweed Family) side. M. Polygonum amphibium L.—water smartweed. (Per- STYLOPHORUM ϩDIPHYLLUM (Michx.) Nutt.—celan- sicaria amphibia (L.) S.F. Gray, P. muhlenbergii dine-poppy, wood-poppy. Comments: One (Meisn. in DC.) Small, Polygonum coccineum plant, in flower, base of Cabin Hill, NE side Muhl. ex Willd., P. muhlenbergii (Meisn. in (D.H. Nicolson, 3 May 2003). I. DC.) S. Watson). (5) M. Beyersdorfer 212, 26 PASSIFLORACEAE (Passion-flower Family) Aug 1982. Bank of channel by ferry dock. AVICULARE L.—knotweed. (P. buxiforme Small). Passiflora lutea L.—yellow passion-flower. (3) E.F. (3) E.P. Killip 32595, 19 Jun 1938. Near bar Wells, R.L. Brown & V.S. Murthy 4417, 25 Jul toward east end [2 sheets]. W. 1997. Floodplain. CESPITOSUM Blume—Asiatic water-pepper. (P. longisetum Bruijn). (11) W.J. Kress & M. Butts PHYTOLACCACEAE (Pokeweed Family) 04-7513, 11 Jun 2004. Mid-island, near north Phytolacca americana L.—pokeweed, pokeberry, shore. I. poke. (6) W.J. Kress & M. Butts 04-7511, 11 ϩCUSPIDATUM Siebold & Zucc.—Japanese knot- Jun 2004. Below Cactus Rock (west side). I. weed. (1) S.G. Shetler, E.F. Wells & R.J. Soreng

2004.39, 30 Oct 2004. NW side, terrace above (3) E.P. Killip 31902, 18 Jul 1936. ‘‘Barrens’’ active floodplain. I. along channel. W. erectum L.—erect knotweed. (1) E.P. Killip & verticillatus L.—swamp dock, water dock. (2) S.F. Blake 36552, 2 Nov 1941. Mudbar below E.P. Killip 32598, 19 Jun 1938. ‘‘Barrens’’ to- sandpile. ward east end, river side. HYDROPIPER L.—common smartweed, water-pepper. (Persicaria hydropiper (L.) Opiz.) (5) E.F. PORTULACACEAE (Purslane Family) Wells, R.L. Brown & V.S. Murthy 4869, 31 Aug Claytonia virginica L.—spring-beauty. (7) W.J. 1997. Floodplain. Kress & M. Butts 04-7440, 6 May 2004. Along ϩ hydropiperoides Michx.—mild water-pepper, path directly below (ENE) terrace. I. Persicaria hydropiperoides false water-pepper. ( PORTULACA OLERACEA L.—common purslane. (2) (Michx.) Small). (4) S.G. Shetler & E.F. Wells E.C. Leonard & N. Hotchkiss 3395, 27 Sep 2004.18, 21 Jul 2004. Mainland, edge of woods 1960. East end, riverbank. I. near Crossing Rocks. I. lapathifolium L.—dock-leaved smartweed. (Per- PRIMULACEAE (Primrose Family) sicaria lapathifolia (L.) S.F. Gray). (12) E.F. Wells, R.L. Brown & V.S. Murthy 5166, 12 Jun ANAGALLIS ARVENSIS L.—scarlet pimpernel, com- 1997. Floodplain. M. mon pimpernel. (1) S.F. Blake s.n., 26 Jul 1924. ORIENTALE L.—prince’s-feather. (Persicaria orien- Lysimachia ciliata L.—fringed loosestrife. (Steiro- talis (L.) Spach). (1) E.P. Killip & J.E. Benedict nema ciliatum (L.) Raf.) (6) E.F. Wells, R.L. 31259, 22 Jul 1934. East sandbar. Brown & V.S. Murthy 4337, 1 Jul 1997. Flood- pensylvanicum L.—pinkweed, Pennsylvania plain. I. smartweed. (Persicaria pensylvanica (L.) M. NUMMULARIA L.—moneywort. (5) W.J. Kress & Go´mez). (12) W.J. Kress & M. Butts 04-7526, M. Butts 04-7491, 25 May 2004. Floodplain 23 Jun 2004. River’s edge of E point. I. near west point. I. ϩ†terrestris (L.) Britton, Sterns & Poggenb.— ϩPERFOLIATUM L.—mile-a-minute, perfoliate tear- swamp loosestrife, swamp-candles. (1) D.L. thumb. (1) E.F. Wells, R.L. Brown & V.S. Mur- Topping s.n., 21 Jun 1897. Near Plummers Is- thy 4336, 1 Jul 1997. Floodplain. M. land [?Mainland]. Comments: Overlooked or PERSICARIA L.—lady’s-thumb. (Persicaria mitis omitted by Killip & Blake (1935, 1953). Gilib., P. persicaria (L.) Small). (6) A.S. Hitch- Samolus parviflorus Raf.—water-pimpernel, brook- cock 15646, 29 Jul 1917. W. weed. (S. floribundus Kunth). (3) E.P. Killip punctatum Elliott—water smartweed, dotted 36546, 2 Nov 1941. Mid-mudbar. smartweed. (Persicaria punctata (Elliott) Small). (10) E.F. Wells, R.L. Brown & V.S. Mur- PYROLACEAE (Shinleaf Family) thy 4536, 21 Sep 1997. Floodplain. I. sagittatum L.—arrow-leaved tearthumb. (Tracau- Chimaphila †maculata (L.) Pursh—spotted winter- lon sagittatum (L.) Small). (2) E.F. Wells, R.L. green. (2) M. Beyersdorfer 80, 2 Jun 1982. Brown & V.S. Murthy 4548, 21 Sep 1997. Mainland, off main trail to ferry. Floodplain. scandens L.—false buckwheat. (Bilderdykia scan- RANUNCULACEAE (Buttercup Family) dens (L.) Greene). (8) E.F. Wells, R.L. Brown Anemone americana H. Hara—hepatica, round- & V.S. Murthy 4484, 20 Sep 1997. Floodplain. lobed hepatica. (Hepatica americana (DC.) Ker tenue Michx.—slender knotweed. (1) T.H. Kear- Gawl.) (4) M. Beyersdorfer 7, 18 Apr 1982. ney 33, 19 Aug 1903. Mainland, south of the Northwest Swamp. virginianum L.—jumpseed. (Tovara virginiana quinquefolia L.—wood anemone, windflower. (3) (L.) Raf.) (7) W.J. Kress & N.A. Bourg 04-7581, A.S. Hitchcock 12806, 7 May 1916. 7 Aug 2004. W side upland forest at base of virginiana L.—thimblewood, tall anemone. (8) S. hill, facing I-495. I. Wiser 2, 11 Jul 1986. West end, sandy soil. Rumex ACETOSELLA L.—sheep sorrel. (2) A.S. Anemonella thalictroides (L.) Spach—rue-anemo- Hitchcock 12765, 6 Jun 1915. ne, windflower. (Syndesmon thalictroides (L.) altissimus A. Wood—pale dock, water dock. (10) Hoffmanns. ex Britton, Thalictrum thalictroides W.J. Kress & M. Butts 04-7492, 25 May 2004. (L.) Eames & B. Boivin). (1) E.P. Killip 30862, Floodplain near west point. I. 29 Apr 1933. Mainland, near main trail. Com- CRISPUS L.—curly dock. (1) A.S. Hitchcock 12689, ments: ‘‘Reported from Island also’’ (Killip & 31 May 1915. I. Blake 1935). OBTUSIFOLIUS L.—bitter dock, broad-leaved dock. Aquilegia canadensis L.—wild columbine, Canadi-

an columbine. (4) E.C. Leonard 3122, 30 Apr woods near Northwest Swamp. Comments: 1960. Near west end, rock outcrop of old chan- Once native here, but these specimens could be nel. I. from plantings (McAtee 1930, p. 54). Cimicifuga racemosa (L.) Nutt.—black snakeroot, black cohosh, bugbane. (3) M. Beyersdorfer ROSACEAE (Rose Family) 129, 10 Jun 1983. East end, lowlands. M, W. Clematis viorna L.—leather-flower, vase-vine. Agrimonia †parviflora Aiton—small-fruited agri- (Viorna urnigera Spach). (10) M. Beyersdorfer mony. (1) E.P. Killip 31085, 19 Aug 1933. Be- 210, 26 Aug 1982. Northwest side of Island. tween Stewart Farm and north fence, near mid- †virginiana L.—virgin’s-bower. (1) E.P. Killip dle gate. 13323, 9 Sep 1928. [Mainland], edge of Stewart pubescens Wallr.—downy agrimony, hairy agri- Farm. mony. (11) M. Beyersdorfer 131, 18 Aug 1983. CONSOLIDA AJACIS (L.) Schur.—rocket larkspur. West end, opposite inlet of stream that goes un- (Delphinium ajacis L., D. ambiguum L., mis- der Beltway. W. applied). (1) E.P. Killip 32596, 19 Jun 1938. rostellata Wallr.—woodland agrimony. (A. eupa- ‘‘Barrens’’ toward east end, river side. toria L., misapplied). (2) E.P. Killip 31109, 4 Delphinium tricorne Michaux—dwarf larkspur. Sep 1933. West Knoll. (Killip & Blake 1935). Amelanchier arborea (F. Michx.) Fernald—com- Ranunculus abortivus L.—kidney-leaved crowfoot, mon serviceberry, downy serviceberry, shad- kidney-leaved buttercup, small-flowered crow- bush. (A. canadensis (L.) Medik., misapplied). foot, aborted buttercup. (8) E.F. Wells, R.L. (1) E.P. Killip 31147, 21 Apr 1934. Mainland, Brown & V.S. Murthy 4331, 15 May 1997. near old spring. Comments: ‘‘. . . formerly re- Floodplain. I. ported from Island also’’ (Killip & Blake BULBOSUS L.—bulbous buttercup, bulbous crow- 1953). I. foot. (1) E.P. Killip 40520, 7 May 1950. East Aruncus †dioicus (Walter) Fernald—goat’s-beard. end near junction of trails to Crossing Rocks and (A. vulgaris (Maxim.) Raf. ex Hara). (1) E.P. East Sandbar. M. Killip 31047, 25 Jun 1933. Mainland, woods be- hispidus Michaux—hispid buttercup, swamp but- tween main trail and Stewart Farm. Comments: tercup. (R. septentrionalis Poir.) (7) S.F. Blake Apparently introduced (McAtee 1930). s.n., 7 May 1933. Ferry landing side of Island. Crataegus uniflora Muenchh.—one-flowered haw- micranthus Nutt.—small-flowered crowfoot. (7) thorn, dwarf hawthorn. (1) E.P. Killip 31179, 30 E.P. Killip 31146, 22 Apr 1934. Near Outlook May 1934. Mainland, main trail near Fisher Rock. Garden. Comments: ‘‘. . . two plants formerly on recurvatus Poir.—hooked crowfoot. (3) W.J. Island also’’ (Killip & Blake 1935). I. Kress & M. Butts 04-7442, 6 May 2004. Along DUCHESNEA INDICA (Andrews) Focke—false straw- path, directly below (ENE) terrace. I. berry, Indian-strawberry. (2) W.J. Kress & M. sceleratus L.—cursed crowfoot. (2) E.C. Leonard Butts 04-7478, 15 May 2004. Mid-island. Com- 21124, 30 Apr 1960. [Mainland], bed of drained ments: Reported without voucher specimen by [C&O] Canal opposite Island. Killip & Blake (1935). I. Thalictrum coriaceum (Britton) Small—thick- Fragaria virginiana Duchesne—wild strawberry. leaved meadow-rue, leatherleaf meadow-rue. (T. (3) E.F. Wells, R.L. Brown & V.S. Murthy 4517, caulophylloides Small). (12) W.J. Kress & M. 21 Sep 1997. Floodplain. Butts 04-7482, 20 May 2004. Central plain Geum †aleppicum Jacq.—yellow avens. (G. stric- (SW). I. tum Aiton). (1) E.P. Killip 31074, 13 Aug 1933. pubescens Pursh—tall meadow-rue, late meadow- Mainland, along lower trail. rue. (T. polygamum Muhl. ex Spreng.) (2) M. canadense Jacq.—white avens. (G. meyerianum Beyersdorfer 118, 10 May 1983. Flats, east end Rydb.) (12) W.J. Kress & M. Butts 04-7517, 11 by Sycamore Cove, path from east end [2 Jun 2004. Floodplain, mid-island. I. sheets]. Malus †SYLVESTRIS Mill.—apple. (M. pumila Mill., revolutum DC.—skunk meadow-rue, wax-leaved misapplied., Pyrus malus L.) (1) E.P. Killip meadow-rue, purple meadow-rue. (4) A.S. 31474, 5 May 1935. Mainland, Stewart Farm. Hitchcock 12932, 24 Jun 1917. Comments: Undoubtably persisting from cultivation. RHAMNACEAE (Buckthorn Family) Physocarpus opulifolius (L.) Maxim.—ninebark. (Opulaster opulifolius (L.) Kuntze). (5) E.C. Ceanothus †americanus L.—New Jersey-tea. (2) Leonard & N. Hotchkiss 3493, 9 May 1961. E.P. Killip 32135, 20 Jun 1937. [Mainland], West end, rock crevice.

Porteranthus †trifoliatus (L.) Britton—bowman’s- flagellaris Willd.—northern dewberry, dewberry. root, false ipecac, Indian-physic. (Gillenia tri- (R. baileyanus Britton, R. camurus L.H. Bailey, foliata (L.) Moench). (1) E.P. Killip 31183, 30 R. enslenii Tratt., R. procumbens Muhl., mis- May 1934. Mainland, west of main trail about applied, R. prosper L.H. Bailey). (12) W.J. 30 ft south of fence. Kress & M. Butts 04-7465, 13 May 2004. E side Potentilla arguta Pursh—tall cinquefoil (five-fin- of Cactus Rock. I. ger). (1) E.P. Killip 31995, 11 Oct 1936. Bar ϩhispidus L.—swamp dewberry, dewberry. (2) midway between Cactus Rock and Outlook M. Beyersdorfer 76, 10 May 1983. West end, Rock. rocky table, behind Rock of Gibraltar. canadensis L.—common cinquefoil (five-finger), occidentalis L.—black raspberry. (2) P.C. Stan- running cinquefoil. (P. pumila Poir.) (3) P.C. dley 11428, 9 May 1915. Standley 11456, 9 May 1915. I. pensilvanicus Poir.—blackberry, Pennsylvania norvegica L.—rough cinquefoil (five-finger), blackberry. (R. ostryifolius Rydb., R. par L.H. strawberry-weed. (P. monspeliensis L.) (3) E.P. Bailey). (3) E.P. Killip 31103, 3 Sep 1933. Near Killip 31252, 21 Jul 1934. West sandbar. Cactus Rock. simplex Michx.—old-field cinquefoil (five finger), PHOENICOLASIUS Maxim.—wineberry. (3) W.J. common cinquefoil. (P. canadensis L., misap- Kress & M. Butts 04-7483, 20 May 2004. Cen- plied). (2) A.S. Hitchcock 12562, 9 May tral plain (SW). I. 1915. W. SPIRAEA †THUNBERGII Siebold ex Blume—Thun- Prunus americana Marshall—wild plum. (6) E.P. berg’s meadowsweet. (1) E.P. Killip 30877, 6 Killip 36654, 18 Jul 1943. [Mainland], along May 1933. [Mainland], Barton Property (intro- C&O Canal between Locks 10 and 11. duced). Comments: ‘‘Escape’’ (Killip & Blake ϩangustifolia Marshall—chickasaw plum. (1) 1935). P.C. Standley 13107, 30 Apr 1916. On rocks at upper end. Comments: Identity subject to ques- RUBIACEAE (Madder Family) tion. Specimen overlooked or discounted by Kil- lip & Blake (1935, 1953). In a spring-flowering Cephalanthus occidentalis L.—buttonbush. (8) W.J. list of W.L. McAtee for Apr 23, 1911 (WBFC Kress & M. Butts 04-7556, 1 Jul 2004. W point Archives). of Island, rocks near I-495 bridge. I. AVIUM L.—sweet cherry. (3) M. Beyersdorfer 37, Diodia teres Walter—buttonweed, rough button- 28 Apr 1983. Mainland, near Canal fence by weed. (2) E.P. Killip 32183, 15 Aug 1937. Northwest Swamp. ‘‘Barrens’’ north of gap between hills. †PERSICA (L.) Batsch—peach. (Killip & Blake Galium aparine L.—cleavers. (5) E.F. Wells, R.L. 1935). Brown & V.S. Murthy 4345, 1Jul 1997. Flood- serotina Ehrh.—wild black cherry, wild cherry. plain. I. (5) W.J. Kress & M. Butts 04-7553, 1 Jul 2004. circaezans Michx.—wild licorice, forest bedstraw. Cliff above W point. I. (6) E.C. Leonard & N. Hotchkiss 3225, 27 Sep PYRUS †COMMUNIS L.—pear. (1) E.P. Killip 31177, 1960. West slope of High Knoll. 27 May 1934. Mainland, Barton Property. Com- concinnum Torr. & A. Gray—shining bedstraw. ments: Undoubtedly persisting from cultivation. (5) M. Beyersdorfer 132, 4 Jul 1982. Gap Rosa carolina L.—pasture rose. (8) N. Hotchkiss & floor. M. E.C. Leonard 3307, 27 Sep 1960. Upper Gap [3 pilosum Aiton—hairy bedstraw. (3) A.S. Hitch- sheets]. cock 13013, 15 Jul 1917. ϩMULTIFLORA Thunb.—multiflora rose. (1) M. Be- †tinctorium (L.) Scop.—southern three-lobed yersdorfer 112, 26 May 1983. Mainland, old bedstraw, wild madder. (2) E.P. Killip 13209, 24 picnic grove by Lock 12–13, just next to Belt- Jun 1928. Mainland, west of trail, near Canal [2 way. I. sheets]. palustris Marshall—swamp rose. (1) E.P. Killip triflorum Michx.—sweet-scented bedstraw. (3) 31260, 22 Jul 1934. Mainland, Northwest E.P. Killip 36845, 3 Aug 1947. Swamp. Houstonia caerulea L.—bluets, Quaker-ladies. Rubus ϩallegheniensis Porter—common blackber- (Hedyotis caerulea (L.) Hook.) (4) M. Beyers- ry. (10) N. Hotchkiss & E.C. Leonard 3188, 23 dorfer 34, 28 Apr 1983. Mainland, high knoll Jul 1960. Cactus Rock, ledge on cliff facing riv- just to the left of main path to ferry dock. M. er [5 sheets]. longifolia Gaertn.—long-leaved bluets, long- argutus Link—tall blackberry, southern blackber- leaved summer bluets. (Hedyotis longifolia ry. (6) E.P. Killip 31202, 3 Jun 1934. Mainland, (Gaertn.) Hook.) (1) C.L. Pollard & P. Dowell near pools west of old spring. W. 28, 16 Aug 1903.

purpurea L.—large summer bluets. (6) W.J. Kress SCROPHULARIACEAE (Figwort Family) & M. Butts 04-7499, 27 May 2004. West side of cabin. I. Agalinis auriculata (Michx.) Blake—auricled agal- Mitchella repens L.—partridge-berry. (4) M. Be- inis, auricled gerardia. (Gerardia auriculata yersdorfer 88, 2 Jun 1982. West end, rocks. Michx., Otophylla auriculata (Michx.) Small, Tomanthera auriculata (Michx.) Raf.) (2) E.P. Killip 31940, 30 Aug 1936. Along river close to RUTACEAE (Rue Family) channel [2 sheets]. Ptelea trifoliata L.—hop-tree, wafer-ash. (3) W.J. Chelone glabra L.—white turtlehead. (Killip & Kress & M. Butts 04-7477, 13 May 2004. Near Blake 1935). beach at SW end. Comments: Earlier collection Gratiola neglecta Torr.—clammy hedge-hyssop. (G. of D.L. Topping (s.n., 1897) apparently not seen virginiana L., misapplied). (5) S. Wiser 7, 11 Jul by Killip & Blake in 1935. Killip’s 32600 was 1986. West end, near bank of channel. actually collected by W.T. Swingle (Killip & Linaria VULGARIS Mill.—butter-and-eggs, toadflax. Blake 1953). I. (2) P.C. Standley 11778, 27 Jun 1915. South shore. Lindernia dubia (L.) Pennell—false pimpernel. (Il- SALICACEAE (Willow Family) ysanthes attenuata (Spreng.) Small, I. dubia L. Populus deltoides Bartram ex Marshall—cotton- Barnhart). (10) E.F. Wells, R.L. Brown & V.S. wood. (P. virginiana Foug.) (9) M. Beyersdorfer Murthy 4531, 21 Sep 1997. Floodplain. I. 289, 19 Sep 1982. West end, river rocks. I. Mecardonia acuminata (Walter) Small—purple Salix †BABYLONICA L.—weeping willow. (Killip & hedge-hyssop, water-hyssop. (Bacopa acumina- Blake 1935). ta (Walter) B.L. Rob.) (4) E.P. Killip 32678, 3 caroliniana Michx.—Carolina willow, Ward’s wil- Sep 1939. Gap, west side. low. (S. wardii (Bebb) Bebb). (6) M. Beyers- Mimulus alatus Aiton—winged monkey-flower. (7) dorfer 368, 17 Oct 1982. West end path around M. Beyersdorfer 132, 18 Aug 1983. West end of Rock of Gibraltar. Island by stream inlet under Beltway. M, W. ϩ†humilis Marshall—prairie willow, upland wil- ringens L.—common monkey-flower, square- low, small pussy willow. (1) C.L. Pollard s.n., stemmed monkey-flower. (2) E.P. Killip 31945, 4 Apr 1897. [Mainland], bank of Canal, oppo- 5 Sep 1936. Pool about halfway between ferry site Island. Comments: Pollard’s specimen over- landing and upper end. looked by Killip & Blake (1935, 1953). Also in PAULOWNIA TOMENTOSA (Thunb.) Siebold & Zucc. one of W.L. McAtee’s spring-flowering lists, ex Steud.—empress-tree, princess-tree, imperi- 1912 (WBFC Archives). al-tree. (1) E.F. Wells, R.L. Brown & V.S. Mur- nigra Marshall—black willow. (6) M. Beyersdor- thy 4515, 21 Sep 1997. Floodplain. I. fer 120, 26 Sep 1982. East end. M, W. Penstemon hirsutus (L.) Willd.—hairy beard- tongue, northeastern beard-tongue. (4) A.K. SAURURACEAE (Lizard’s-tail Family) Fisher s.n., 18 May 1941. Along trail to east end, east of new ferry post. Saururus cernuus L.—lizard’s-tail. (3) E.C. Leon- laevigatus Aiton—smooth beard-tongue, eastern ard & N. Hotchkiss 3269, 27 Sep 1960. Upper beard-tongue. (2) E.P. Killip 32117, 13 Jun Gap, alluvial soil between rock outcrops. Com- 1937. Near upper end, in path of flood. Com- ments: Gone from the Island in 1935 (Killip & ments: Specimen of D.L. Topping (s.n., 1897), Blake: ‘‘Extinct?’’) but present again by 1946 misidentified as P. digitalis (Sweet) Nutt., ap- (Killip & Blake 1953). I. parently overlooked by Killip & Blake (1935,1953). SAXIFRAGACEAE (Saxifrage Family) Scrophularia marilandica L.—Maryland figwort, eastern figwort. (3) W.J. Kress & M. Butts 04- Heuchera americana L.—common alumroot, rock- 7566, 22 Jul 2004. Along trail near E point. I. geranium. (8) M. Beyersdorfer 12-84, 21 May VERBASCUM BLATTARIA L.—moth mullein. (3) E.P. 1984. West Knoll, rocky outcrop. Killip 31972, 20 Sep 1936. Path of main current Hydrangea arborescens L.—wild hydrangea, Amer- of flood near upper end. ican hydrangea. (5) E.C. Leonard & N. Hotch- PHLOMOIDES L.—clasping-leaved mullein. (3) E.P. kiss 3158, 23 Jul 1960. West end of West Knoll. Killip 36557, 11 Oct 1941. Mudbar at east end. Saxifraga virginiensis Michx.—early saxifrage. (6) Comments: New to DC area at the time (Killip M. Beyersdorfer 53, 28 Apr 1982. West face of & Blake 1953). Cabin Hill, rocky outcroppings. I. THAPSUS L.—common mullein, great mullein. (4)

M. Beyersdorfer 266, 12 Sep 1982. Behind Solanum carolinense L.—horse-nettle. (5) W.J. Rock of Gibraltar, rock crevice on rock table. I. Kress & M. Butts 04-7539, 23 Jun 2004. SW Veronica ϩamericana Schwein. ex Benth.—Amer- shore, at water’s edge. I. ican brooklime, American speedwell. (2) S. Wis- nigrum L. s.l.—black nightshade. (S. americanum er & C. Van Metre 71, 3 Oct 1986. Along chan- Mill., perhaps misapplied, S. nodiﬂorum Jacq., nel west of cabin, in rock crevices. Comments: S. ptychanthum Dunal). (9) W.J. Kress & M. Specimen of P.C. Standley (11773, 1915) ap- Butts 04-7514, 11 Jun 2004. Mid-island, near parently overlooked by Killip & Blake (1935, north shore. I. 1953). ϩ†PHYSALIFOLIUM Rusby—hairy nightshade. (S. anagallis-aquatica L.—water speedwell, brook- sarrachoides Sendt., misapplied). (1) S.G. She- pimpernel. (V. glandifera Pennell). (4) S.G. She- tler & E.F. Wells 2004.19, 21 Jul 2004. Main- tler 2004.9, 15 May 2004. Mainland, among land, near Crossing Rocks. M. rocks at Rock Crossing. M. ARVENSIS L.—corn speedwell. (2) A.S. Hitchcock STAPHYLEACEAE (Bladdernut Family) 12581, 9 May 1915. Staphylea trifolia L.—bladdernut. (11) W.J. Kress HEDERIFOLIA L.—ivy-leaved speedwell. (7) W.J. Kress & M. Butts 04-7446, 6 May 2004. Along & M. Butts 04-7434, 6 May 2004. Along path path directly below (ENE) terrace. I. to cabin. I. peregrina L.—purslane speedwell. (3) F. Pennell 2861A, 4 Jun 1941. East end of Island. THYMELAEACEAE (Mezereum Family) Veronicastrum virginicum (L.) Farw.—culver’s- Dirca palustris L.—leatherwood. (4) E.C. Leonard root. (Leptandra virginica (L.) Nutt.) (7) E.C. 3113, 30 Apr 1960. Outcrop near west end, Leonard & N. Hotchkiss 3320, 27 Sep 1960. among rocks. I. Rock outcrop of Upper Gap. TILIACEAE (Linden Family) SIMAROUBACEAE (Quassia Family) Tilia americana L.—basswood, American linden. AILANTHUS ALTISSIMA (Mill.) Swingle—tree-of- (T. heterophylla Vent., T. neglecta Spach). (8) heaven. (5) W.J. Kress & M. Butts 04-7555, 1 W.J. Kress & M. Butts 04-7554, 1 Jul 2004. Jul 2004. Slope above beach near SW point. I. Cliff above SW point. I.

SOLANACEAE (Nightshade Family) ULMACEAE (Elm Family) Datura stramonium L.—jimson-weed. (10) W.J. Celtis occidentalis L.—hackberry, northern hackber- Kress & M. Butts 04-7540, 23 Jun 2004. SW ry. (C. crassifolia Lam.) (21) W.J. Kress & N.A. shore, beach. I. Bourg 04-7584, 29 Aug 2004. On rocks on W LYCOPERSICON ESCULENTUM Mill.—tomato. (4) M. side below cabin. I. Beyersdorfer 395, 24 Oct 1982. Entrance to ϩtenuifolia Nutt.—dwarf hackberry. (C. pumila channel. Pursh, misapplied). (1) A.S. Hitchcock 12782, NICANDRA PHYSALODES (L.) Gaertn.—apple-of-Peru. 13 Jun 1915. Comments: Annotated as ‘‘C. mis- (Physalodes peruvianum (Mill.) Kuntze). (1) sissippiensis Bosc’’ (ϭ C. laevigata Willd.) and E.P. Killip 31947, 7 Sep 1936. ‘‘Barrens’’ to- treated as that species in Hitchcock & Standley ward lower end. (1919) and Killip & Blake (1935). I. PETUNIA AXILLARIS (Lam.) Britton, Sterns & Pog- Ulmus americana L.—American elm. (6) M. Be- genb.—common garden petunia. (P. violacea yersdorfer 121, 27 Jun 1982. West end. I. Lindl.,? misapplied). (1) E.P. Killip & J.R. rubra Muhl.—slippery elm, red elm. (U. fulva Swallen 31928, 16 Aug 1936. Michx.) (14) W.J. Kress & M. Butts 04-7557, 1 Physalis heterophylla Nees—clammy ground-cher- Jul 2004. W point, rocks near I-495 bridge. I. ry, common ground-cherry. (4) E.P. Killip 31055, 25 Jun 1933. [Mainland], Stewart Farm. URTICACEAE (Nettle Family) longifolia Nutt.—smooth ground-cherry, longleaf ground-cherry. (P. philadelphica Lam., misap- Boehmeria cylindrica (L.) Sw.—false nettle. (11) plied, P. subglabrata Mack. & Bush). (12) W.J. E.F. Wells, R.L. Brown & V.S. Murthy 4877, 31 Kress & N.A. Bourg 04-7573, 31 Jul 2004. On Aug 1997. Floodplain. I. rock outcrop at E end. I. Laportea canadensis (L.) Wedd.—wood-nettle. (Ur- pubescens L.—hairy ground-cherry, downy ticastrum divaricatum (L.) Kuntze). (6) E.F. ground-cherry. (3) E.F. Wells, R.L. Brown & Wells, R.L. Brown & V.S. Murthy 4502, 20 Sep V.S. Murthy 4533, 21 Sep 1997. Floodplain. 1997. Floodplain. I.

Parietaria pennsylvanica Muhl. ex Willd.—pellito- cucullata Aiton—blue marsh violet. (1) E.P. Killip ry. (1) A.S. Hitchcock 12916, 24 Jun 1917. W. 30874, 6 May 1933. Flats north of Cabin Hill. Pilea pumila (L.) A. Gray—richweed, clearweed. (6) palmata L.—wood violet, palmate-leaved violet. E.F. Wells, R.L. Brown & V.S. Murthy 4552, 21 (Viola stoneana House, V. triloba Schwein., Sep 1997. Floodplain. misapplied). (6) E.C. Leonard & N. Hotchkiss Urtica dioica L.—stinging nettle, nettle. (U. gracilis 3483, 9 May 1961. West slope of High Knoll. Aiton, U. procera Muhl. ex Willd.) (12) W.J. pubescens Aiton—downy yellow violet, smooth Kress & M. Butts 04-7501, 27 May 2004. Mid- yellow violet. (V. eriocarpa (Nutt.) Schwein., V. island near north shore. I. pensylvanica Michx.) (8) E.F. Wells, R.L. Brown & V.S. Murthy 4886, 27 Apr 1998. VALERIANACEAE (Valerian Family) Floodplain. I. sororia Willd.—common blue violet. (V. papilion- Valeriana pauciflora Michx.—valerian. (9) W.J. acea Pursh). (23) M. Beyersdorfer 47, 28 Apr Kress & M. Butts 04-7479, 13 May 2004. Mid- 1983. Path from east end to Cabin Hill by Syc- island near north shore. I. amore Cove. W. Valerianella LOCUSTA (L.) Latourr.—European corn- striata Aiton—creamy violet, striped violet. (13) salad, blue corn-salad. (V. olitoria (L.) Pollich). W.J. Kress & M. Butts 04-7438, 6 May 2004. (7) E.P. Killip 36692, 25 May 1945. Trail on Terrace. I. ‘‘Barrens’’ about 20 ft. east of ferry trail. triloba Schwein.—three-lobed violet. (2) E.C. ϩ radiata (L.) Dufr.—beaked corn-salad. (1) E.F. Leonard & N. Hotchkiss 3505, 9 May 1961. Wells, R.L. Brown & V.S. Murthy 4332, 15 May Trail (upper) to ferry, rock outcrop. 1997. Floodplain. VITACEAE (Grape Family) VERBENACEAE (Vervain Family) AMPELOPSIS ϩ†BREVIPEDUNCULATA (Maxim.) Phyla lanceolata (Michx.) Greene—fogfruit. (Lippia Trautv.—porcelain-berry. (A. heterophylla lanceolata Michx.) (4) S.G. Shetler & S.S. Orli (Thunb.) Siebold & Zucc.) (1) S.G. Shetler & 2004.28, 3 Aug 2004. Bank of channel, near E.R. Shetler 2004.37, 11 Oct 2004. Mainland, crossing rocks. M. towpath where trail to Island cuts off—just be- Verbena hastata L.—blue vervain, common ver- low Lock 11. M. vain. (4) S.G. Shetler & S.S. Orli 2004.25, 3 Parthenocissus quinquefolia (L.) Planch.—Virgin- Aug 2004. Small rock island in middle of chan- ia-creeper. (6) W.J. Kress & M. Butts 04-7469, nel. I. 13 May 2004. Cactus Rock. I. simplex Lehm.—narrow-leaved vervain. (V. an- Vitis aestivalis Michx.—summer grape, pigeon gustifolia Michx.) (1) A.S. Hitchcock 12690, 31 grape. (V. argentifolia Munson). (6) E.C. Leon- May 1915. ard & N. Hotchkiss 3179, 23 Jul 1960. Cactus urticifolia L.—white vervain. (6) W.J. Kress & M. Rock, climbing on trees and shrubs. W. Butts 04-7525, 23 Jun 2004. Rivers edge at E †labrusca L.—fox grape. (2) E.P. Killip 31184, point. I. 30 May 1934. Mainland, near Northwest Swamp. Comments: Probably introduced VIOLACEAE (Violet Family) (McAtee 1930, p. 54). riparia Michx.—riverbank grape, frost grape. (V. Hybanthus concolor (T.F. Forst.) Spreng.—green vi- cordifolia Michx., misapplied, V. vulpina L., olet. (Cubelium concolor (T.F. Forst.) Raf.) (11) misapplied). (7) W.J. Kress & M. Butts 04-7454, E.C. Leonard 3106, 30 Apr 1960. South slope 11 May 2004. E point, at river’s edge. I. of West Knoll. rupestris Scheele—sand grape, sugar grape. (2) ϩ Viola affinis Leconte—Leconte’s violet. (1) G.P. A.K. Fisher s.n., Jun 1906 [2 sheets]. Van Eseltine 266, 15 Apr 1915. Comments: This vulpina L.—frost grape, winter grape, chicken specimen, collected as ‘‘Viola familiaris’’ in grape. (V. cordifolia Michx., V. riparia Michx., 1915 and annotated V. affinis by Ezra Brainerd misapplied). (11) E.C. Leonard & N. Hotchkiss in 1917, apparently was overlooked or ignored 3250, 27 Sep 1960. Rock of Gibraltar. I. by Killip & Blake (1935, 1953). Some (e.g., Gleason & Cronquist 1991) include V. affinis in MONOCOTYLEDONS V. sororia. M. ALISMATACEAE bicolor Pursh—field pansy, wild pansy. (V. kitai- (Water-plantain or Arrowhead Family) beliana Roem. & Schult. var. rafinesquei (Greene) Fernald, V. rafinesquei Greene). (4) Alisma subcordatum Raf.—common water-plan- A.S. Hitchcock 12583, 9 May 1915. tain. (A. plantago-aquatica L. var. parviflorum

(Pursh) Torr.) (2) E.C. Leonard & N. Hotchkiss albicans Willd. ex Spreng.—white-tinged sedge, 3587, 9 May 1961. Damp alluvial bank of chan- Emmon’s sedge. (C. artitecta Mack., C. emmon- nel above ferry. sii Dewey, C. varia Host, misapplied). (11) Col- Sagittaria latifolia Willd.—common arrowhead, lector Unknown 4161, 1 May 1971. I. broad-leaved arrowhead, duck-potato, wapato. ϩ†albolutescens Schwein.—green-white sedge. (S. pubescens Muhl. ex Nutt.) (7) E.C. Leonard (C. straminea Willd. ex Schkuhr, misapplied). 3592, 9 May 1961. Damp grassy bank below (1) C. Lea 1485, 11 May 2000. [Mainland], be- ferry [2 sheets]. W. tween C&O Canal and Potomac River, edge of montevidensis Cham. & Schltdl.—giant arrow- vernal pool, south of Lock 12. head, Mississippi arrowhead, tidal sagittaria. albursina E. Sheld.—white bear sedge. (6) E.P. (Lophotocarpus calycinus (Engelm.) J.G. Sm.) Killip 31029, 4 Jun 1933. I. (1) E.P. Killip 13484, 28 Sep 1930. In deep pool †amphibola Steud.—eastern narrow-leaf sedge. just off sandbar at west end. (5) C. Lea 1482, 11 May 2000. Mainland, be- rigida Pursh—sessile-fruited arrowhead. (1) E.P. tween C&O Canal and Potomac River, south of Killip 13496, 5 Oct 1930. Pool at east end. Lock 12. I. annectens (E.P. Bicknell) E.P. Bicknell—yellow- ARACEAE (Arum Family) fruit sedge. (4) E.P. Killip 36826, 30 May 1947. Arisaema dracontium (L.) Schott—green-dragon. Gap at upper end [2 sheets]. (4) E.F. Wells, R.L. Brown & V.S. Murthy 5151, †atlantica L.H. Bailey—bog sedge, prickly bog 12 Jun 1997. Floodplain. sedge, Howe’s sedge. (C. cephalantha (L.H. triphyllum (L.) Schott—jack-in-the-pulpit, Indi- Bailey) E.P. Bicknell, misapplied, C. incomperta an-turnip. (5) M. Beyersdorfer 28, 25 Apr 1982. E.P. Bicknell). (2 sheets of 1 collection) P.C. At base of Cabin Hill by ferry path. I. Standley 11663, 6 Jun 1915. Mainland. Orontium ϩaquaticum L.—golden-club. Low blanda Dewey—charming sedge, eastern wood- swale at inner edge of mudflat along river below land sedge. (10) E.P. Killip 32444, 8 May 1938. Cabin (observed in vegetative condition by E.F. ‘‘Barrens’’ near sand bank, east end. I. Wells, 31 Aug 1997). W. cephalophora Muhl. ex Willd.—oval-leaf sedge. Peltandra virginica (L.) Schott—arrow-arum, tuck- (10) W.J. Kress & M. Butts 04-7460, 13 May ahoe, green arrow-arum. (4) M. Beyersdorfer 2004. South corner of cabin. I. 149, 14 Jul 1982. Mainland swamp on northwest ϩcommunis L.H. Bailey—fibrous-root sedge. (C. corner of property by Lock 12 and 13. M. pedicellata (Dewey) Britton). (3) E.C. Leonard & N. Hotchkiss 3485A, 9 May 1961. Upper Gap, COMMELINACEAE (Dayflower Family) west end [2 sheets]. Comments: Kearney & Commelina COMMUNIS L.—Asiatic dayflower. (7) Maxon s.n., 1902, apparently overlooked by Kil- W.J. Kress & N.A. Bourg 04-7577, 31 Jul 2004. lip & Blake (1935, 1953). W side, on rock outcrop terrace, 50m below cab- †comosa Boott—bearded sedge. (1) P.C. Standley in, facing I-495. Comments: Earliest collection, 11633B, 6 Jun 1915. Mainland, edge of pool in T.H. Kearney 167, 30 Aug 1903, apparently woods. Comments: Indicated by Killip & Blake never seen by Killip & Blake (1935, 1953). I. (1935) to be on Island as well as Mainland, but erecta L.—slender dayflower, white-mouth day- there are no voucher specimens preserved from flower. (C. virginica L., misapplied). (10) E.C. Island. Leonard & N. Hotchkiss 3149, 23 Jul 1960. ϩconjuncta Boott—soft fox sedge. (1) E.P. Killip Trail bordering river between Cabin Hill and 31188, 30 May 1934. West end. Comments: west end. This specimen and, thus, this species overlooked virginica L.—Virginia dayflower. (C. erecta L., by Killip & Blake (1935, 1953). I. misapplied, C. hirtella Vahl). (9) S. Wiser & W. †crinita Lam.—fringed sedge. (4) E.P. Killip Burket 34, 14 Aug 1986. East end, near crossing 31035, 10 Jun 1933. Mainland, swamp near old rocks; open area midway between channel and spring. Comments: Indicated by Killip & Blake river. (1935) to be on Island as well as Mainland, but Tradescantia virginiana L.—Virginia spiderwort, there are no voucher specimens preserved from widow’s-tears. (11) W.J. Kress & M. Butts 04- Island. 7457, 11 May 2004. Cactus Rock. I. frankii Kunth—Frank’s sedge. (C. stenolepis Torr.) (7) S.G. Shetler 95-1, 17 Oct 1995. East CYPERACEAE (Sedge Family) end, sunny bank on river side. Carex ϩaggregata Mack.—glomerate sedge. (2) ϩgracilescens Steud.—slender loose-flowered M.T. Strong 3350, 3351, 1 May 2004 [unmount- sedge. (1) M. T. Strong 3342, 1 May 2004 [un- ed as of Dec 2004]. mounted as of Dec 2004].

†gracillima Schwein.—graceful sedge. (1) P.C. minea Willd. ex Schkuhr, misapplied). (3) P.C. Standley 11663, 6 Jun 1915. Mainland, edge of Standley 11651, 6 Jun 1915. Upper end, among pool in deep woods. rocks. granularis Muhl. ex Willd.—limestone-meadow oligocarpa Schkuhr ex Willd.—rich-woods sedge, sedge. (2) E.P. Killip 32934,— May 1940 [2 few-fruited sedge. (7) C. Lea 1481, 11 May sheets]. Comments: Mainland or Island?—exact 2000. Mainland, between C&O Canal and Po- collection site not known, according to label of tomac River, south of Lock 12. sheet no. 03150290. The label of this sheet also pensylvanica Lam.—Pennsylvania sedge. (4) E.P. indicates that Killip himself was not the collec- Killip 13656, 10 May 1931. [Mainland], near tor, as further confirmed in Killip & Blake old spring. I. (1953, ‘‘collector uncertain’’). ϩplanispicata Naczi—flat-spiked sedge. (C. am- grayi J. Carey—Gray’s sedge. (C. asa-grayi L.H. phibola Steud., in part). (1) P.C. Standley Bailey). (7) W.J. Kress & M. Butts 04-7496, 25 11399, 9 May 1915. I. May 2004. Floodplain near NW point. Com- †prasina Wahlenb.—drooping sedge. (C. miliacea ments: Apparently overlooked by Killip & Muhl. ex Schkuhr). (2) C. Lea 957, 21 May Blake (1935, 1953) despite E.P. Killip’s 1933 1995. [Mainland], near Island. M. collection (31015, 2 sheets). I. radiata (Wahlenb.) Small—eastern star sedge. (C. grisea Wahlenb.—inflated narrow-leaf sedge. (C. convoluta Mack., misapplied, C. rosea Schkuhr amphibola Steud., in part). (3) E.P. Killip ex Willd., misapplied). (10) C. Lea 483, 21 May 31014, 29 May 1933. Near west end. W. 1995. [Mainland], near Island, grassy edge of hirsutella Mack.—hirsute sedge, fuzzy-wuzzy towpath. I. sedge. (C. complanata Torr. & Hook., in part, retroflexa Muhl. ex Schkuhr—reflexed sedge. (3) C. triceps of authors, not Michx.) (4) E.P. Killip E.P. Killip 31173, 27 May 1934. Mainland, near 31009, 28 May 1933. West trail, south of West main trail. Knoll. rosea Schkuhr ex Willd.—rosy sedge. (C. convo- hirtifolia Mack.—pubescent sedge. (2) E.P. Killip luta Mack.) (2) E.C. Leonard & N. Hotchkiss & S.F. Blake 31193, 2 Jun 1934. Just east of 3195, 23 Jul 1960. Near summit of Cabin Hill, Cabin. along trail from ferry to cabin. hitchcockiana Dewey—Hitchcock’s sedge. (1) scoparia Schkuhr ex Willd.—pointed broom E.P. Killip 30865, 6 May 1933. West foot of sedge. (C. cristellata Britton, misapplied). (4) Cabin Hill. E.P. Killip 32651, 4 Jun 1939 [2 sheets]. jamesii Schwein.—James’ sedge. (C. steudelii †shortiana Dewey—Short’s sedge. (3) E.P. Killip Kunth). (5) E.P. Killip 13677, 31 May 1921. 13203, 24 Jun 1928. Mainland, along lower trail Foot of west side of Cabin Hill. I. [2 sheets]. †laevivaginata (Ku¨k.) Mack.—smooth-sheathed sparganioides Muhl. ex Willd.—bur-reed sedge. sedge. (3) C. Lea 960, 21 May 1995. [Main- (7) E.P. Killip 31016, 30 May 1933. Near cabin. land], near Island, wooded swamp. ϩsquarrosa L.—squarrose sedge. (2) W.J. Kress laxiflora Lam.—loose-flowered sedge. (C. anceps & M. Butts 04-7497, 25 May 2004. Floodplain Muhl.) (2) E.C. Leonard & N. Hotchkiss 3476A, near NW point. Comments: P.C. Standley 9 May 1961. Upper Gap, west end, rock out- 11644, 1915, overlooked by Killip & Blake crop. (1935, 1953). I. LEAVENWORTHII Dewey—Leavenworth’s sedge. stipata Muhl. ex Willd.—stalkgrain sedge. (2) (1) P.C. Standley 11433, 9 May 1915. E.P. Killip 32613, 26 Jun 1938. Near entrance lupulina Muhl. ex Willd.—hop sedge. (4) E.P. to channel, marshy streamlet. I. Killip 36626, 12 Jul 1942. Mainland, large Frog tribuloides Wahlenb.—blunt broom sedge. (C. Pond. cristellata Britton). (10) W.J. Kress & M. Butts lurida Wahlenb.—sallow sedge. (3) E.P. Killip 04-7498, 25 May 2004. Floodplain near NW 32614, 26 Jun 1938. Near entrance to channel, point. I. marshy streamlet. virescens Muhl. ex Willd.—ribbed sedge. (7) W.J. muhlenbergii Schkuhr ex Willd.—Muhlenberg’s Kress & M. Butts 04-7472, 13 May 2004. Below sedge. (C. plana Mack.) (1) E.P. Killip 13358, Cactus Rock on W side. I. 30 May 1930. Outlook Rock, near west end. vulpinoidea Michx.—foxtail sedge. (2) E.P. Killip nigromarginata Schwein.—black-edged sedge, 32607, 19 Jun 1938. Marshy streamlet, near en- black-margined sedge. (2) E.P. Killip 30888, 7 trance to channel [2 sheets]. May 1933. Mainland, northwest corner near willdenowii Schkuhr ex Willd.—Willdenow’s fence. W. sedge. (3) E.P. Killip 31197, 3 Jun 1934. Main- normalis Mack.—greater straw sedge. (C. stra- land, Northwest Swamp. I.

Cyperus bipartitus Torr.—shining cyperus, shining S.F. Blake 36555, 2 Nov 1941. Mudbar, between flatrush. (C. diandrus Torr., misapplied, C. ri- Rock of Gibraltar and channel [2 sheets]. vularis Kunth). (3) E.P. Killip 31965, 13 Sep engelmannii Steud.—Engelmann’s spikerush. (1) 1936 [2 sheets]. E.P. Killip 31871, 5 Jul 1936. Near pools half- echinatus (L.) A.W. Wood—globose cyperus, way between ferry and upper end. globe flatsedge. (C. ovularis (Michx.) Torr.) (2) obtusa (Willd.) Schult.—blunt spikerush. (6) E.C. E.C. Leonard & N. Hotchkiss 3311, 27 Sep Leonard & N. Hotchkiss 3566, 9 May 1961. 1960. Upper Gap, small pocket in outcropping West end, south side, riverbank. rocks. tenuis (Willd.) Schult.—slender spikerush, kill- erythrorhizos Muhl.—red-rooted galingale, red- cow, doghair. (E. capitata (L.) R. Br., misap- root flatsedge. (9) E.F. Wells, R.L. Brown & V.S. plied). (2) E.P. Killip 41376, 24 Aug 1951. Murthy 4458, 31 Aug 1997. Floodplain. Among rocks. esculentus L.—yellow nutsedge, chufa, edible nut- Fimbristylis autumnalis (L.) Roem. & Schult.— grass, yellow nutgrass. (7) W.J. Kress & M. slender fimbry. (F. mucronulata (Michx.) S.F. Butts 04-7549, 1 Jul 2004. SW point (rocks). I. Blake). (1) A.S. Hitchcock 15863, 7 Oct 1917. flavescens L.—yellow galingale, yellow flatsedge. Scirpus atrovirens Willd.—black bulrush, dark (3) M. Beyersdorfer 337, 26 Sep 1982. Midway green bulrush. (4) A.S. Hitchcock 12960, 1 Jul between Cactus Rock and Rock of Gibraltar, 1917. cracked mud on river flats at large rock outcrop cyperinus (L.) Kunth—wool-grass, cottongrass protruding into river. bulrush. (S. eriophorum Michx., S. rubricosus lancastriensis Porter ex A. Gray—Lancaster’s cy- Fernald). (5) E.C. Leonard & N. Hotchkiss perus, many-flowered flatsedge. (6) E.F. Wells, 3292, 27 Sep 1960. Upper Gap, soil pockets on R.L. Brown & V.S. Murthy 4409, 30 Jul 1997. rock outcrops [2 sheets]. W. Floodplain. ϩgeorgianus R.M. Harper—Georgia bulrush. (S. ϩlupulinus (Spreng.) Marcks—slender cyperus, atrovirens var. georgianus (R.M. Harper) Fer- Great Plains flatsedge. (C. filiculmis Vahl, mis- nald). (1) E.P. Killip 32606, 9 Jun 1938. Near applied). (1) E.P. Killip 32633, 17 Aug 1938. entrance to channel, marsh streamlet [as S. atro- South of West Knoll, woods between trail and virens]. rocks [misidentified as C. filiculmis Vahl]. ϩodoratus L.—fragrant galingale, rusty flatsedge. (C. speciosus Vahl). (5) E.F. Wells, R.L. Brown DIOSCOREACEAE (Yam Family) & V.S. Murthy 4521, 21 Sep 1997. Floodplain. Dioscorea villosa L.—wild yam, yam-root, colicroot. Comments: E.C. Leonard & E.P. Killip 2116 (8 (D. glauca Muhl. ex Bartlett, D. quaternata J.F. Nov 1931) apparently overlooked by Killip & Gmel.) (11) M. Beyersdorfer 81, 10 May 1983. Blake (1935, 1953). On path through gap to west end [2 sheets]. M. pseudovegetus Steud.—green galingale, marsh flatsedge. (2) E.P. Killip 41356, 28 Jul 1951. Upper Gap, pool [2 sheets]. HYDROCHARITACEAE (Frog-bit Family) refractus Engelm. ex Boeck.—reflexed cyperus, reflexed flatsedge. (C. engelmannii Steud., mis- Elodea ϩcanadensis F. Michx.—common water- applied). (9) E.C. Leonard & N. Hotchkiss 3249, weed, Canada waterweed. (Anacharis canaden- 27 Sep 1960. West slope of High Knoll, rock sis (Michx.) Planch.) (2) E.P. Killip 40542, 7 outcrop. Aug 1950. Mainland, long pool near rocks to squarrosus L.—awned cyperus, awned flatsedge. dam. Comments: Both specimens misidentified (C. aristatus Rottb.) (6) E.F. Wells, R.L. Brown as Najas guadalupensis (Spreng.) Morong. & V.S. Murthy 4453, 31 Aug 1997. Floodplain. nuttallii (Planch.) H. St. John—western water- strigosus L.—straw-colored cyperus, false nut- weed, free-flowered waterweed. (Anacharis sedge, galingale, straw-colored flatsedge. (9) canadensis (Michx.) Planch., misapplied, A. oc- S.G. Shetler & S.S. Orli 2004.12, 30 Jun 2004. cidentalis (Pursh.) Vict., E. canadensis Michx., Rocky islet off east end of Island. I. misapplied, E. occidentalis (Pursh) H. St. John). Dulichium arundinaceum (L.) Britton—three-way (2) E.P. Killip 32656, 9 Jul 1939. Large pool sedge, three-square sedge. Comments: Reported north of gap between Cabin Hill and West by Killip & Blake (1935), who added the query, Knoll. ‘‘Extinct?’’ Vallisneria americana Michx.—eel-grass, wild-cel- Eleocharis acicularis (L.) Roem. & Schult.—least ery, water-celery. (V. spiralis L.) (1) E.P. Killip spikerush, needle spikerush. (3) E.P. Killip & 13457, 24 Aug 1930. In pool at west end.

IRIDACEAE (Iris Family) 5 Sep 1982. Crossing Rocks. Comments: Lemna obscura also on this sheet [US3062125]. BELAMCANDA CHINENSIS (L.) DC.—blackberry-lily, Wolffia columbiana H. Karst.—water-meal. (2) P.C. leopard-flower. (Gemmingia chinensis (L.) Kun- Standley 11664, 6 Jun 1915. Mainland, pool in tze). (Killip & Blake 1935). deep woods. Comments: This US sheet Iris versicolor L.—blue flag, northern blue flag. (2) (895246) also includes Spirodela polyrrhiza and M. Beyersdorfer 42, 13 May 1982. [Mainland], is filed under that name. banks of C&O Canal. Comments: ‘‘Also observed on Island’’ (Killip & Blake, 1935). Sisyrinchium angustifolium Mill.—narrow-leaved LILIACEAE (Lily Family) blue-eyed-grass, stout blue-eyed-grass. (S. gra- mineum Lam.) (4) W.J. Kress & M. Butts 04- Allium canadense L.—meadow garlic, wild onion, 7500, 27 May 2004. Central plain (west of cab- wild garlic. (2) W.J. Kress & M. Butts 04-7468, in). I. 13 May 2004. Cactus Rock. I. cernuum Roth—nodding onion, wild onion. (8) JUNCACEAE (Rush Family) E.C. Leonard & N. Hotchkiss 3206, 23 Jul 1960. West end, crevices of rock outcrop [2 sheets]. I. Juncus acuminatus Michx.—sharp-fruited rush, tricoccum Aiton—ramp, wild leek. (7) W.J. Kress knotty-leaved rush. (3) E.P. Killip 31845, 5 Jul & M. Butts 04-7528, 23 Jun 2004. Directly be- 1936. ‘‘Barrens’’ above ferry landing. low terrace (SE side). I. bufonius L.—toad rush. (1) E.P. Killip 32605, 19 VINEALE L.—wild garlic, field garlic, crow garlic. Jun 1938. Upper Gap, near large pool. (3) E.F. Wells, R.L. Brown & V.S. Murthy 5163, dichotomus Elliott—forked rush. (J. platyphyllus 12 Jun 1997. Floodplain. I. (Wiegand) Fernald, J. tenuis var. platyphyllus ASPARAGUS OFFICINALIS L.—asparagus. (Killip & (Wiegand) F.J. Herm.) (5) E.P. Killip 31862, 13 Blake 1935). Sep 1936. Between ferry and upper end. Com- Erythronium albidum Nutt.—white trout-lily, white ments: These specimens treated as J. dudleyi fawn-lily, white dog’s-tooth-violet, white ad- Wiegand or J. tenuis by Killip & Blake (1935, der’s-tongue. (7) M. Beyersdorfer 27, 14 Apr 1953). 1983. Path from east end, next to path by bend effusus L.—soft rush, common rush, lamp rush. at Sycamore Cove. (4) E.C. Leonard & N. Hotchkiss 3313, 27 Sep americanum Ker Gawl.—yellow trout-lily, yellow 1960. Upper Gap, small rock pool. W. fawn-lily, yellow dog’s-tooth-violet, yellow ad- marginatus Rostk.—grass-leaved rush. (1) E.P. der’s-tongue. (5) M. Beyersdorfer 4-84, 11 May Killip 31858, 5 Jul 1936. Near pools halfway 1984. Cabin Hill. I. between ferry and upper end. HEMEROCALLIS FULVA L.—orange daylily, common secundus P. Beauv. ex Poir.—lopsided rush. (J. daylily. (2) M. Beyersdorfer 76, 2 Jun 1982. tenuis var. secundus (P. Beauv. ex Poir.) En- Mainland, bank by Crossing Rocks. W. gelm.) (2) E.P. Killip & S.F. Blake 36547, 2 MUSCARI BOTRYOIDES (L.) Mill.—common grape- Nov 1941. Mid-mudbar. hyacinth. (3) E.P. Killip & J.E. Benedict Jr. tenuis J. macer E.F. Willd.—path rush. ( Gray). (3) 31749, 19 Apr 1936. Just east of Landing Rock. Wells, R.L. Brown & V.S. Murthy 4407, 30 Jul NEGLECTUM Guss. ex Ten.—blue-bottle, grape-hy- 1997. Floodplain. I. acinth. (M. racemosum (L.) Lam. & DC., misapplied, M. racemosum (L.) Mill., misapplied). LEMNACEAE (Duckweed Family) (2) A.S. Hitchcock 12409, 18 Apr 1915. Lemna ϩminor L.—common duckweed. (1) E.C. NARCISSUS ϫMEDIOLUTEUS Mill. (N. poeticus L. ϫ Leonard & N. Hotchkiss 3590, 9 May 1961. tazetta L.)—poetaz narcissus, primrose narcis- Channel above ferry, on mud and surface of wa- sus. (N. ϫbiflorus W. Curtis, N. poetaz Hort. ex ter. L.H. Bailey). (1) A.S. Hitchcock 12446, 25 Apr ϩobscura (Austin) Daubs—little water duckweed. 1915. (1) M. Beyersdorfer 234, 5 Sep 1982. Com- ϩPOETICUS L.—poet’s narcissus, pheasant’s-eye. ments: Collection mixed with Spirodela polyr- (1) P.C. Standley 11302, 25 Apr 1915. Flats at rhiza on US sheet 3062125. lower end. Comments: This specimen apparent- perpusilla Torr.—minute duckweed. (4) E.P. Kil- ly overlooked or discounted by Killip & Blake lip 36743, 17 Aug 1946. Mainland, Frog Ponds. in 1935. Spirodela polyrrhiza (L.) Schleid.—greater duck- †PSEUDONARCISSUS L.—common daffodil. (2) E.P. weed, water-flaxseed, common duck-meal. Killip 36978, 10 Apr 1949. Mainland, lower (Lemna polyrrhiza L.) (5) M. Beyersdorfer 234, trail, near trail to Crossing Rocks [2 sheets].

Comments: ‘‘A single plant, which has not re- Hotchkiss 3285, 27 Sep 1960. Upper Gap, be- appeared’’ (Killip & Blake 1953). tween rock outcrops. ORNITHOGALUM †NUTANS L.—nodding star-of-Beth- Liparis liliifolia (L.) Rich. ex Lindl.—lily-leaved lehem. (2) M. Beyersdorfer 26, 25 Apr 1982. twayblade, large twayblade. (2) T.H. Kearney Mainland, off to left of path from Lock 11 to 21, 19 Aug 1903. river. loeselii (L.) Rich.—Loesel’s twayblade, yellow UMBELLATUM L.—star-of-Bethlehem, sleepydick. twayblade. (1) A.S. Hitchcock 15827, 16 Sep (4) M. Beyersdorfer ?-84, 11 May 1984. East 1917. end, sandy alluvium—flood deposit. Spiranthes †lacera (Raf.) Raf.—slender ladies’- Polygonatum biflorum (Walter) Elliott—smooth tresses. (Ibidium beckii (Lindl.) House, I. gracile Solomon’s-seal. (P. canaliculatum (Muhl. ex (Bigelow) House, S. beckii Lindl., S. gracilis Willd.) Pursh, misapplied, P. commutatum (Bigelow) Beck). (1) E.P. Killip 31083, 13 Aug (Schult. & Schult. f.) A. Dietr., P. giganteum A. 1933. [Mainland], west of Stewart Farm and Dietr.) (6) M. Beyersdorfer 25, 11 Apr 1982. north of Fisher Farm. West Knoll Ϫ 2nd highest point of Island. I. tuberosa Raf.—little ladies’-tresses. (Ibidium be- Smilacina racemosa (L.) Desf.—false Solomon’s- ckii, sense of House, S. beckii Lindl., misap- seal, false spikenard, plumelily. (Maianthemum plied). (1) S.F. Blake 8903, 5 Oct 1924. Slope racemosum (L.) Link, Vagnera racemosa (L.) west of cabin. Morong). (9) E.F. Wells, R.L. Brown & V.S. Tipularia discolor (Pursh) Nutt.—cranefly orchid. Murthy 4374, 30 Jul 1997. Floodplain. I. (T. unifolia (Muhl.) Britton, Sterns & Poggenb.) Trillium sessile L.—toadshade, sessile trillium. (25) (3) M. Beyersdorfer 129, 18 Aug 1983. Main- W.J. Kress & M. Butts 04-7487, 20 May 2004. land, next to the Frog Ponds. M. Central plain (west of cabin). I. Triphora trianthophora (Sw.) Rydb.—nodding-po- Uvularia perfoliata L.—perfoliate bellwort, mealy gonia, three-birds orchid. (3) H.K. Svenson & bellwort. (1) A.S. Hitchcock 12577, 9 May 1915. E.P. Killip 45705, 18 Aug 1956. Mainland.

NAJADACEAE (Naiad or Water-nymph Family) POACEAE (Grass Family) Najas flexilis (Willd.) Rostk. & W.L.E. Schmidt— Agrostis GIGANTEA Roth—redtop. (A. alba L., mis- wavy naiad, wavy water-nymph, northern water- applied, A. palustris Huds., in part, A. stoloni- nymph. (2) E.P. Killip & N. Hotchkiss 31984, fera L., in part). (5) F.J. Hermann 9543, 2 Jul 11 Oct 1936. Pool about halfway between ferry 1938. North end, bank of river. landing and upper end. †hyemalis (Walter) Britton, Sterns & Poggenb.— guadalupensis (Spreng.) Magnus—Guadalupe na- tickle grass, hair grass. (1) J.E. Benedict Jr. iad, Guadalupe water-nymph. (N. flexilis, mis- 3261, 7 Jun 1936. [Mainland], near Lock 11, applied). (1) E.P. Killip 13462, 7 Sep 1930. open field. Shallow water near sandbar at east end. perennans (Walter) Tuck.—upland bent grass, autumn bent grass. (9) E.C. Leonard 3309A, 27 ORCHIDACEAE (Orchid Family) Sep 1960. Upper Gap, west end, rock outcrop Aplectrum hyemale (Muhl. ex Willd.) Torr.—put- crevices. tyroot, Adam-and-Eve. (4) A.S. Hitchcock Andropogon gerardii Vitman—big bluestem. (A. 12921, 24 Jun 1917. furcatus Muhl. ex Willd.) (4) E.C. Leonard & Corallorhiza ϩodontorhiza (Willd.) Nutt.—autumn N. Hotchkiss 3508, 9 May 1961. West end, on coral-root, small coral-root. (1) H.S. Barber s.n., rocks. 12 Oct 1907. Comments: Barber’s specimen ap- virginicus L.—broom-sedge. (3) E.C. Leonard & parently overlooked by Killip & Blake (1935, N. Hotchkiss 3255, 27 Sep 1960. Outlook Rock, 1953). west end. ϩwisteriana Conrad—Wister’s coral-root, spring ANTHOXANTHUM ODORATUM L.—sweet vernal grass. coral-root. (1) T.H. Kearney s.n., 9 May 1915. (Killip & Blake 1935). Near west end, toward Maryland shore. Com- Aristida dichotoma Michx.—poverty grass. (2) E.C. ments: Kearney’s specimen apparently over- Leonard & N. Hotchkiss 3252, 27 Sep 1960. looked by Killip & Blake (1935, 1953). Outlook Rock, west end. Galearis spectabilis (L.) Raf.—showy orchid. (Or- purpurascens Poir.—arrow-feather three-awn. (1) chis spectabilis L.) (Killip & Blake 1935). E.P. Killip & J.R. Swallen 32222, 19 Sep 1937. Goodyera pubescens (Willd.) R. Br. ex W.T. Aiton— Outlook Rock. downy rattlesnake-plantain. (Peramium pubes- ARTHRAXON ϩHISPIDUS (Thunb.) Makino—arthrax- cens (Willd.) MacMill.) (3) E.C. Leonard & N. on, small carp grass. (A. ciliaris P. Beauv. var.

cryptatherus Hack.) (3) E.F. Wells, R.L. Brown nosum (Elliott) Gould, D. lindheimeri (Nash) & V.S. Murthy 5171, 12 Jun 1997. Floodplain. Gould, Panicum acuminatum Sw., P. huachu- Brachyelytrum erectum (P. Beauv. ex Schreb.) P. chae Ashe, P. lindheimeri Nash, P. tennesseense Beauv. (3) E.C. Leonard & N. Hotchkiss 3251, Ashe). (15) M. Beyersdorfer 183, 15 Aug 1982. 27 Sep 1960. Lookout Rock, west end. West Knoll. Bromus COMMUTATUS Schrad.—hairy chess, upright boscii (Poir.) Gould & C.A. Clarke—Bosc’s panic chess, meadow brome. (1) E.P. Killip 36689, 29 grass, Bosc’s rosette grass. (Panicum boscii May 1945. Trail on ‘‘Barrens’’ north of east end Poir.) (11) S.G. Shetler & S.S. Orli 2004.30, 3 of Cabin Hill. W. Aug 2004. Woods near Northwest Swamp. I. JAPONICUS Thunb.—Japanese chess, Japanese clandestinum (L.) Gould—deer-tongue grass, brome. (1) E.P. Killip & J.R. Swallen 31876, 12 deer-tongue rosette grass. (Panicum clandestin- Jul 1936. ‘‘Barrens’’ near east end. W. um L.) (3) E.C. Leonard & N. Hotchkiss 3175, LATIGLUMIS (Scribn. ex Shear) Hitchc.—early-leaf 23 Jul 1960. Cactus Rock. brome. (B. incanus (Shear) Hitchc., B. purgans commutatum (Schult.) Gould—variable panic L., misapplied). (8) J.R. Swallen 9965, 14 Sep grass, variable rosette grass. (Panicum ashei G. 1947. Pearson ex Ashe, P. commutatum Schult.) (8) ϩnottawayanus Fernald—Nottoway Valley W.J. Kress & M. Butts 04-7505, 8 Jun 2004. brome. (4) J.R. Swallen 9660-9662,—Jun 1947. Floodplain near north shore. I. Comments: A.S. Hitchcock s.n., 1906, and Swal- depauperatum (Muhl.) Gould—starved panic len specimens overlooked by Killip & Blake grass, starved rosette grass. (Panicum depau- (1935, 1953). peratum Muhl.) (1) A.S. Hitchcock 12708, 31 pubescens Muhl. ex Willd.—hairy woodland May 1915. brome, Canada brome. (B. purgans L., misap- dichotomum (L.) Gould—bushy panic grass, cy- plied). (7) E.C. Leonard & N. Hotchkiss 3146, press rosette grass. (D. microcarpon (Muhl. ex 23 Jul 1960. Trail on river side of Island be- Elliott) Mohlenbr., D. yadkinense (Ashe) Moh- tween Cabin Hill and west end. W. lenbr., Panicum barbulatum Michx., P. dicho- Cenchrus longispinus (Hack.) Fernald—field sand- tomum L., P. microcarpon Muhl. ex Elliott, P. bur, common sandbur. (C. pauciflorus Benth., yadkinense Ashe). (17) R.S. Cowan 1682, 4 Jun misapplied (Hitchcock & Standley 1919, Her- 1961. West slope of Cabin Hill. mann 1946)). (1) E.P. Killip & J.R. Swallen ϩlatifolium (L.) Harvill—broad-leaved panic 31904, 19 Jul 1936. ‘‘Barrens’’ at east end. grass. (Panicum latifolium L.) (1) T.H. Kearney Chasmanthium latifolium (Michx.) H.O. Yates— & W.R. Maxon 59, 24 Jul 1910. Rich woods. wild oats, Indian wood-oats. (Uniola latifolia Comments: This specimen apparently over- Michx.) (12) W.J. Kress & N.A. Bourg 04-7588, looked by Killip & Blake (1935, 1953). 29 Aug 2004. Bottomland below rocks on W laxiflorum (Lam.) Gould—lax-flowered panic side below cabin. I. grass, open-flowered rosette grass. (Panicum Cinna arundinacea L.—common woodreed, Indian- laxiflorum Lam., P. xalapense Kunth). (5) E.C. reed. (6) S.G. Shetler & S.S. Orli 2004.23, 3 Leonard & N. Hotchkiss 3226, 27 Sep 1960. Aug 2004. Northwest Swamp. M. West slope of West Knoll. CYNODON DACTYLON (L.) Pers.—Bermuda grass, linearifolium (Scribn.) Gould—low panic grass, scutch grass. (Capriola dactylon (L.) Kuntze). slim-leaved rosette grass. (Panicum linearifol- (Killip & Blake 1935). ium Scribn., P. werneri Scribn.) (5) E.C. Leon- DACTYLIS GLOMERATA L.—orchard grass. (1) E.P. ard & N. Hotchkiss 3185, 23 Jul 1960. Cliff face Killip 32146, 12 Jul 1937. ‘‘Barrens’’ at foot of of Cactus Rock facing river. W. trail uphill from ferry. sphaerocarpon (Elliott) Gould—round-fruited Danthonia spicata (L.) P. Beauv. ex Roem. & panic grass, round-seed rosette grass. (D. po- Schult.—poverty grass, poverty oat grass. (3) lyanthes (Schult.) Mohlenbr., Panicum polyan- E.P. Killip 32134, 20 Jun 1937. [Mainland], thes Schult., P. sphaerocarpon Elliott). (6) E.C. woods near Northwest Swamp. J.R. Swallen, Leonard & N. Hotchkiss 3287, 27 Sep 1960. coll. Upper Gap, west end, rock crevices. Dichanthelium aciculare (Desv. ex Poir.) Gould & villosissimum (Nash) Freckmann—white-haired C.A. Clarke—needle-leaf panic grass, needle- panic grass, white-haired rosette grass. (Pani- leaf rosette grass. (Panicum bicknellii Nash, cum pseudopubescens Nash, P. villosissimum misapplied). (3) A.S. Hitchcock 12948, 1 Jul Nash). (1) J.R. Swallen s.n., 5 Jul 1936. About 1917. halfway along trail to upper end. acuminatum (Sw.) Gould & C.A. Clark—hairy Digitaria ISCHAEMUM (Schreb.) Schreb. ex Muhl.— panic grass, tapered rosette grass. (D. lanugi- smooth crab grass, small crab grass. (Synther-

isma ischaemum (Schreb.) Nash). (3) E.F. pectinacea (Michx.) Nees—pink grass, purple Wells, R.L. Brown & V.S. Murthy 4508, 21 Sep love grass, Carolina love grass. (E. caroliniana 1997. Floodplain. (Biehler) Scribn., misapplied). (5) M. Beyers- SANGUINALIS (L.) Scop.—crab grass, northern crab dorfer s.n., 2 Sep 1984. Sandy flats just west of grass, hairy crab grass. (Syntherisma sanguinalis Cactus Rock. (L.) Dulac). (5) E.C. Leonard & N. Hotchkiss PILOSA (L.) P. Beauv.—India love grass. (E. mul- 3296, 27 Sep 1960. Upper Gap, west end. ticaulis Steud., E. peregrina Wiegand). (1) E.P. Echinochloa CRUSGALLI (L.) P. Beauv.—large barn- Killip & J.R. Swallen 32163, 1 Aug 1937. Low- yard grass. (7) E.F. Wells, R.L. Brown & V.S. er end, east of sandpile. Murthy 4396, 30 Jul 1997. Floodplain. spectabilis (Pursh) Steud.—purple love grass, ϩmuricata (P. Beauv.) Fernald—rough barnyard tumble grass, trouble-grass. (E. pectinacea grass. (E. crusgalli var. mitis (Pursh) Peterm., E. (Michx.) Nees, misapplied). (1) A.S. Hitchcock pungens (Poir.) Rydb.) (1) S. Wiser & C. Van 15829, 16 Sep 1917. Metre 48, 11 Sep 1986. West end, west of Cac- Festuca subverticillata (Pers.) E.B. Alexeev—nod- tus Rock; rocky ‘‘islands’’ directly offshore in ding fescue. (F. obtusa Biehler). (6) E.F. Wells, river. R.L. Brown & V.S. Murthy 4410, 30 Jul 1997. ELEUSINE INDICA (L.) Gaertn.—yard grass, wire Floodplain. grass, Indian goose grass. (2) E.F. Wells, R.L. Glyceria †septentrionalis Hitchc.—floating manna Brown & V.S. Murthy 4524, 21 Sep 1997. grass, eastern manna grass. (Panicularia septen- Floodplain. I. trionalis (Hitchc.) E.P. Bicknell). (1) E.P. Killip Elymus hystrix L.—bottle-brush grass. (Hystrix pa- 36572, 17 May 1942. Mainland, in middle of tula Moench). (6) W.J. Kress & M. Butts 04- Frog Pond nearest old spring. 7508, 8 Jun 2004. Floodplain near NW point. I. striata (Lam.) Hitchc.—fowl manna grass, nerved ϩmacgregorii R.E. Brooks & J.J.N. Campb.— manna grass. (G. nervata (Willd.) Trin., Pani- Macgregor’s wild rye. (1) W.J. Kress & M. Butts cularia nervata (Willd.) Kuntze). (2) A.S. Hitch- 04-7493b, 25 May 2004. Floodplain near NW cock 12696, 31 May 1915. point. I. Leersia oryzoides (L.) Sw.—rice cut grass. (Hom- ϩriparius Wiegand—riverbank wild rye. (1) W.J. alocenchrus oryzoides (L.) Pollich). (4) E.C. Kress & M. Butts 04-7493a, 25 May 2004. Leonard & N. Hotchkiss 3408, 27 Sep 1960. Floodplain near NW point. I. East end, sub-island at upper rock crossing of villosus Muhl. ex Willd.—downy wild rye, slender channel. wild rye. (E. striatus Willd., misapplied). (7) virginica Willd.—white grass. (Homalocenchrus E.P. Killip 42238, 9 Aug 1952. Upper Gap, west virginicus (Willd.) Britton). (5) E.F. Wells, R.L. of rock near cattail pool. I. Brown & V.S. Murthy 4519, 21 Sep 1997. virginicus L.—Virginia wild rye grass, Terrell Floodplain. grass. (E. australis Scribn. & C.R. Ball, E. gla- LOLIUM MULTIFLORUM Lam.—annual rye grass, Ital- briflorus (Vasey) Scribn. & C.R. Ball, E. striatus ian rye grass. (L. perenne ssp. multiflorum Willd.) (21) E.F. Wells, R.L. Brown & V.S. Mur- (Lam.) Husn.) (1) E.P. Killip & N. Hotchkiss thy 4360, 1Jul 1997. Floodplain. 32619, 26 Jun 1938. ‘‘Barrens’’ north of gap Eragrostis capillaris (L.) Nees—lace grass. (4) E.P. between Cabin Hill and West Knoll. Killip & J.R. Swallen 31889, 12 Jul 1936. ‘‘Bar- Melica mutica Walter—two-flowered melic. (4) W.J. rens’’ near ferry landing. Kress & M. Butts 04-7461, 13 May 2004. Near CILIANENSIS (All.) Vignolo ex Janch.—stink grass. Cactus Rock. I. (2) E.P. Killip & J.R. Swallen 31905, 19 Jul MICROSTEGIUM ϩVIMINEUM (Trin.) A. Camus—Jap- 1936. ‘‘Barrens’’ at east end near river. anese stilt grass, coverall grass, Nepalese frankii C.A. Mey. ex Steud.—sandbar love grass, browntop. (Eulalia viminea (Trin.) Kuntze). (1) Frank’s love grass. (6) S. Wiser & C. Van Metre E.F. Wells, R.L. Brown & V.S. Murthy 4474, 12 47, 11 Sep 1986. West end, to west of Cactus Sep 1997. Floodplain. I. Rock; floodplain by river. W. Muhlenbergia frondosa (Poir.) Fernald—wire-stem hypnoides (Lam.) Britton, Sterns & Poggenb.— muhly. (M. mexicana (L.) Trin., misapplied). (7) teal love grass. (E. reptans (Michx.) Nees, in E.C. Leonard & N. Hotchkiss 3348, 27 Sep part). (13) E.F. Wells, R.L. Brown & V.S. Mur- 1960. Boat landing, sandy riverbank. thy 4509, 21 Sep 1997. Floodplain. schreberi J.F. Gmel.—nimblewill. (2) E.C. Leon- MINOR Host—little love grass. (E. poaeoides P. ard & N. Hotchkiss 3397, 27 Sep 1960. East Beauv. ex Roem. & Schult.) (1) E.P. Killip & end, riverbank. J.R. Swallen 32162, 1 Aug 1937. Lower end sobolifera (Muhl. ex Willd.) Trin.—branched east of sandpile. muhly, rock muhly. (2) J.R. Swallen & J.E. Ben-

edict s.n., 17 Oct 1937. Front of cabin along trail sylvestris A. Gray—forest blue grass, sylvan blue to Cactus Rock. grass, woodland blue grass. (4) W.J. Kress & M. Panicum anceps Michx.—flat-stemmed panic grass, Butts 04-7453, 6 May 2004. NE corner of cab- beaked panic grass. (1) A.S. Hitchcock 15774, 9 in. I. Sep 1917. TRIVIALIS L.—rough-stemmed blue grass, rough capillare L.—witch grass, old-witch grass, com- blue grass. (2) A.S. Hitchcock 12687, 31 May mon panic grass. (3) M. Beyersdorfer 358, 10 1915. Oct 1982. West Knoll, path on channel side by SCHEDONORUS ϩARUNDINACEUS (Schreb.) Dumort.— rock-tree ring. tall fescue, alta fescue, tall rye grass. (Festuca dichotomiflorum Michx.—spreading witch grass, arundinacea Schreb., F. elatior L.) (2) E.C. fall panic grass. (7) E.C. Leonard & N. Hotch- Leonard & N. Hotchkiss 3191, 23 Jul 1960. East kiss 3358, 27 Sep 1960. East end, Poachers end of Island [2 sheets]. Landing. PRATENSIS (Huds.) P. Beauv.—meadow fescue, gatteringi Nash—Gattinger’s panic grass. (8) E.C. meadow rye grass. (Festuca elatior L., misap- Leonard & N. Hotchkiss 3530, 9 May 1961. plied). (1) E.P. Killip & J.R. Swallen 32125, 20 West end, low bank. Comments: May date un- Jun 1937. West Knoll, north side. likely. Schizachyrium scoparium (Michx.) Nash—little philadelphicum Bernh. ex Trin.—wood witch bluestem, little false bluestem. (Andropogon grass, Philadelphia panic grass. (6) E.F. Wells, scoparius Michx.) (Killip & Blake 1935). R.L. Brown & V.S. Murthy 4534, 21 Sep 1997. Setaria ϩFABERI R.A.W. Herrm.—giant foxtail Floodplain. grass, nodding foxtail grass. (4) W.J. Kress & rigidulum Bosc. ex Nees—red-top panic grass. (P. N.A. Bourg 04-7572, 31 Jul 2004. On rock out- stipitatum Nash). (2) E.P. Killip 36993, 6 Aug crop at E end. I. 1949. Largest pool, near laurel patch. PUMILA (Poir.) Roem. & Schult.—yellow foxtail virgatum L.—switch grass, wand panic grass. (3) grass. (Chaetochloa lutescens (Weigel) Stuntz, E.C. Leonard & N. Hotchkiss 3290, 27 Sep misapplied, Setaria glauca (L.) P. Beauv., in 1960. Upper Gap, west end. part, S. lutescens (Poir.) Roem. & Schult., mis- Paspalum laeve Michx.—smooth paspalum, field applied). (1) A.S. Hitchcock 15766, 9 Sep 1917. crown grass. (P. circulare Nash). (1) E.P. Killip VIRIDIS (L.) P. Beauv.—green foxtail grass, green 36638, 7 Sep 1942. Upper Gap, marsh. bristle grass. (Chaetochloa viridis (L.) Scribn.) repens P.J. Bergius—water paspalum, horsetail (7) E.C. Leonard & N. Hotchkiss 3355, 27 Sep crown grass. (P. fluitans (Elliott) Kunth, P. re- 1960. Boat landing, riverbank. pens var. fluitans (Elliott) Wipff & S.D. Jones). Sorghastrum nutans (L.) Nash—Indian grass, yel- (8) S.G. Shetler & S.S. Orli 2004.24, 3 Aug low Indian grass. (4) E.C. Leonard & N. Hotch- 2004. Small rock island in middle of channel. I. kiss 3596, 9 May 1961. Riverbank near Poach- setaceum Michx.—slender paspalum, slender ers Landing. Comments: May date unlikely. crown grass. (P. pubescens Muhl. ex Willd.) (2) Sphenopholis intermedia (Rydb.) Rydb.—slender E.P. Killip & J.R. Swallen 32138, 4 Jul 1937. wedge grass, slender wedgescale. (S. pallens Flood-swept gap at west end, near river. (Spreng.) Scribn., of Hitchcock &Standley Phalaris arundinacea L.—reed canary grass. (6) 1919). (2) J. R. Swallen 9648, June 1947. Island. W.J. Kress & M. Butts 04-7488, 20 May 2004. nitida (Biehler) Scribn.—shiny wedge grass, shiny Ridge above central plain, mid-island. I. wedgescale. (1) A.S. Hitchcock 12585, 16 May PHLEUM PRATENSE L.—timothy, herd’s grass. (1) 1915. E.P. Killip & J.R. Swallen 31877, 12 Jul 1936. Sporobolus vaginiflorus (Torr. ex A. Gray) A.W. ‘‘Barrens’’ toward lower end. Wood—poverty dropseed, poverty grass. (2) Piptochaetium avenaceum (L.) Parodi—black-seed E.P. Killip & J.R. Swallen 31937, 30 Aug 1936. needle grass, black oat grass. (Stipa avenacea ‘‘Barrens’’ along channel, toward east end. L.) (3) R.S. Cowan 1680, 4 Jun 1961. West slope Tridens flavus (L.) Hitchc.—purpletop, tall redtop. of Cabin Hill [2 sheets]. (Triodia flava (L.) Smyth). (4) S. Wiser & C. Poa COMPRESSA L.—Canada blue grass, flat- Van Metre 57, 11 Sep 1986. West end, to west stemmed blue grass. (1) A.S. Hitchcock 12683, of Cactus Rock, in rock crevices about 20–25Ј 31 May 1915. from shore. cuspidata Nutt.—short-leaved blue grass, early Tripsacum dactyloides (L.) L.—eastern gama grass. blue grass. (1) A.S. Hitchcock 12420, 18 Apr (5) E.C. Leonard & N. Hotchkiss 3310, 27 Sep 1915. 1960. West end, Upper Gap, soil pocket between pratensis L.—Kentucky blue grass. (3) A.S. Hitch- outcrop rocks. cock 12666, 22 May 1915. ZEA MAYS L.—corn, maize. (1) E.P. Killip 31924, 09,

15 Aug 1936 [with small ear]. ‘‘Barrens’’ near (Coleogeton pectinatus (L.) Les & R.R. Haynes, tree bridge. Comments: Temporarily present af- Potamogeton pectinatus L.) (3) E.P. Killip & N. ter floods of 1936, 1937 (Killip & Blake 1953). Hotchkiss 32620, 26 Jun 1938. Pool north of gap between Cabin Hill and West Knoll. Com- PONTEDERIACEAE (Pickerel-weed Family) ments: All three specimens (1908, 1937, 1938) apparently overlooked by Killip & Blake in Heterantha dubia (Jacq.) MacMill.—water-star- 1935 and 1953. grass, grass-leaved mud-plantain. (Schollera graminea Raf. ex A. Gray, Zosterella dubia SMILACACEAE (Greenbrier Family) (Jacq.) Small). (6) S. Wiser & C. Van Metre 75, Smilax glauca L.—sawbrier, glaucous greenbrier. (4) 3 Oct 1986. West end, near Cabin John Bridge W.J. Kress & M. Butts 04-7464, 13 May 2004. on Potomac River side, on muddy shore. E side of Cactus Rock. I. reniformis Ruiz & Pav.—kidney-leaved mud- herbacea L.—smooth carrion-flower. (1) S.F. plantain. ‘‘Extinct’’ (Killip & Blake 1935). Blake s.n., 4 Aug 1934. West End. hispida Raf.—China-root, bristly greenbrier, hell- POTAMOGETONACEAE (Pondweed Family) fetter. (S. tamnoides L., confused name). (4) A.S. Potamogeton ϩCRISPUS L.—curly pondweed. (4) Hitchcock 15821, 16 Sep 1917. E.P. Killip 40545, 27 Aug 1950. Entrance to pulverulenta Michx.—downy carrion-flower. (3) channel, submerged [misidentified as P. foliosus E.P. Killip 31204, 3 Jun 1934. Woods near old Raf.]. spring. diversifolius Raf.—common snail-seed pondweed, rotundifolia L.—common greenbrier, common variable pondweed, waterthread pondweed. (P. catbrier, bullbrier, horsebrier. (10) S.G. Shetler capillaceus Poir., misapplied, P. hybridus 2004.2, 1 May 2004 [2 sheets]. I. Michx., misapplied). (4) E.P. Killip & N. Hotch- kiss 31981, 11 Oct 1936. Halfway between ferry TYPHACEAE (Cattail Family) landing and upper end, pool. Typha ϩangustifolia L.—narrow-leaved cattail. (1) nodosus Poir.—long-leaf pondweed. (P. ameri- E.P. Killip 31873, 5 Jul 1936. In pool halfway canus Cham. & Schltdl.) (4) M. Beyersdorfer between ferry landing and upper end. Com- 351, 10 Oct 1982. Mainland, C&O Canal, across ments: Specimen apparently overlooked by Kil- from Plummers Island. lip & Blake in 1953. ϩpusillus Morong—small pondweed, slender latifolia L.—broad-leaved cattail. (1) E.P. Killip pondweed. (1) E.P. Killip 13459, 24 Aug 1930. 41359, 29 Jul 1951. Largest pool in Upper Gap, West end, in pool [misidentified as P. foliosus near laurel patch. Comments: Reported as ‘‘Ex- Raf.]. tinct’’ by Killip & Blake in 1935, but reinstated Stuckenia ϩpectinata (L.) Bo¨rner—sago-pondweed. in 1953.

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