Report on a 2020 survey for State-listed at

Quonnipaug Lake, Guilford,

Christopher R. Mangels

Botanical - Ecological Consultant

New Fairfield, Connecticut

Submitted to the Town of Guilford

27 December 2020

Survey background, objectives and methods

This report details a brief botanical survey of Quonnipaug Lake (henceforth QL) conducted independently by the author in late August of 2020. The survey was commenced at the request of Kevin Magee, Environmental Planner for Town of Guilford (henceforth TOG), by whom I was contacted to provide outside expertise pertaining to rare species and plant surveys. Need for this survey arose in the context of review by Natural Diversity Database of CT-DEEP (hereafter NDDB) for continued authorization of aquatic application (NDDB Determination No.: 202000699, dated May 29, 2020).

The survey’s primary objective was to investigate the status of two plant species, Capillary pondweed and Water-marigold, both previously known to occur at QL and currently listed as Threatened and Special Concern category species, respectively, by State of Connecticut (CT DEEP, 2015). Assuming one or both species were found, the survey further entailed fully documenting the population(s), including mapping and evaluation of size and viability. Three unaccompanied visits, each lasting 3-5 hours (total field time of 10.5 hours), were made on 26 August, 28 August and 30 August 2020. The aim on the first date was general site reconnaissance, e.g., checking access points and probing near-shore portions of the lake accessible by land. On the two later dates the survey followed a meandering route through the outer littoral zone, a purely visualized area extending roughly 10 meters inward from water’s edge, utilizing a 10-foot single-person kayak with very low draft that allowed access into minimal depths, as necessitated by shallow, mucky conditions at the southern end. A short rake (~1-meter long) was used for retrieving submersed . In a few places where it was feasible to disembark, closer scrutiny was achieved by wading. In practical terms, however, the kayak’s small size and instability made it unsuited for use with a longer rake and for onboard examination of more than a few specimens, thereby precluding more systematic collection of plant material, as is conventional practice in aquatic vegetation studies. Along with plants, photos and GPS points were also taken for identification purposes as well as for future reference.

Due to initial uncertainty about how much time might be required to inspect the entire lake, the survey area was divided into northern and southern sectors, one of which was covered on each of the latter two dates. On both occasions the survey originated from the western side (town beach). In attempt to contain time and cost a small section near the middle of the eastern shoreline, within which neither species had been reported, was excluded per project proposal (see Fig. 1.). Along with site visits, the survey demanded considerable pre- and post-fieldwork review of maps and reports, aerial imagery and relevant scientific literature.

Site description

QL is situated in the northeastern corner of the town of Guilford (USGS Durham Quadrangle), which lies at the convergence of the state’s “South Central Lowlands” and “Southeast Hills” sub-ecoregions (Dowan and Craig, 1976). The surrounding area has an evident history of mixed agricultural and lakeshore recreational land uses, and at the present time QL is characterizable as a moderately dense residential lakeshore settlement. Major landowners and features include a state boat launch, town beach, and Choate Rosemary Hall club house on the western side, opposed by numerous terraced yards, small docks, and some bulk headed frontage along the eastern side. The southern end is largely undeveloped, with a near continuously vegetated shoreline and coves buffered by natural areas (formal or informal) owned by TOG and Guilford Land Conservation Trust. The lake main body covers an area of nearly 99 acres, with a maximum depth exceeding 42 feet and surface elevation of approximately 210 feet a.s.l. (CT DEEP, 2011). There is uncertainty surrounding ownership of open water portions, as is shown by the lack of attribution on town-level GIS, although jurisdiction of the lake bed is assumed by TOG to belong to the State of Connecticut (K. Magee, pers. com.). Fuller knowledge of title and the settlement history of the lake, while relevant and perhaps a matter of record, would have required research beyond the scope of this report.

Judging from a combination of aerial imagery, maps and descriptions in earlier reports and first-hand observation, the lake and its margins encompass an array of vegetation or habitat types, from open water with sparse to dense aquatic beds to fringing forest, and from highly modified to comparatively natural. The transition between these types is in places abrupt, such as along bedrock exposures on the eastern side, while at the southern end, where a small dam and road culvert create impoundment, far more gradual. Much of the vegetation corresponds to lacustrine and palustrine communities described by Metzler and Tiner (1992).

Focal species descriptions

Both focal species are strictly aquatic, naturally submersed, fine-leaved perennial or vegetative annual herbs (see below). While their relative contributions to the diverse macrophyte assemblage that exemplifies the native aquatic flora of QL might be minor, in terms of area—though this has never actually been quantified—generally speaking, such macrophyte assemblages carry high ecological value (Hotchkiss, 1964; Sculthorpe, 1967). Depending on individual size and phenological stage, plants of both species can be difficult to differentiate from many outwardly similar co-occurring species, particularly underwater. Altogether, these points underscore both the potential challenges and the importance of surveying for them.

Capillary pondweed ( gemmiparus), also known as Budding pondweed, is a rare species endemic to New England and neighboring Quebec. Within Connecticut there are six known extant populations currently, all from the coastal and eastern sub-regions (CT DEEP, 2015; CT NDDB, unpublished data). Across New England as a whole the species has been reported from just 30 sites in three states, of which as many as 20 may be historical only (Native Plant Trust, unpublished data; NHESP, 2015). Owing to this narrow geographic range and presumably other factors such as the number of historical-only sites, Capillary pondweed is recognized as a species of conservation concern at regional and national levels, with a rank of R3, defined as “Vulnerable”, meaning at moderate risk of extinction or decline (NatureServe, 2017). However, it has received less research attention than other regional rarities such as Ogden’s pondweed and Straight-leaved pondweed, both of which were subjects of conservation plans (Hellquist & Pike, 2004; Hellquist & Mertinooke-Jongkind, 2003). Consequently, many aspects of its ecology have not been fully elucidated. What is known its reproductive modus and life history has been summarized by Kaplan & Stepanek (2003) and Les (2020): Plants lack but reproduce vegetatively by means of reduced, axillary, bud-like shoots (turions), which are formed near the end of one growing season and begin growth early (May) the following year. These are thought to be the main means of reproduction, with flowering occurring seldomly, especially in deep shaded or turbulent water, and seed recruitment being rare or non-existent. The importance of turions toward annual recruitment has possibly been underestimated due to the similarity of germinated turions to seedlings.

Water marigold ( beckii) is an odd aquatic member of the large, mostly terrestrial Aster family, as evidenced by heads with yellow ray , which are born singly on aerial flowering stems. This species is heterophyllous, i.e., possessing two types, those underwater being larger and finely dissected, with smaller, entire and merely toothed on aerial flowering stems. Its growth habit varies from partly emergent in shallow depths to fully submergent in deeper water, the latter reportedly being more typical. The insect pollinated flowers and fruits are produced in late summer (July-Sept), sometimes in the first year (Strother & Weedon, 2006). Seed set is typically low, and in parts of the range only a small percentage of populations reportedly with regularity (Les, 2018; Scribailo & Alix, 2002). Although its geographic range is wide, extending across Canada and southward to MD and MO, it is considered rare in many of the states where it occurs (NatureServe, 2020; USDA, 2020).

Taxonomic and identification issues

The uniqueness of Water-marigold as a species is shown by its former segregation into the monotypic genus Megalodonta, still used in some references. When flowers are present the plants are virtually unmistakable, although in purely vegetative condition it can surely be overlooked, especially in mixed growths of other fine- leaved plants such as Cabomba and bladderworts (Utricularia species).

Similarly, Capillary pondweed can be cryptic, but adding to this is considerable haziness surrounding its classification, due to its nesting within a species complex (Sect. Pusilli) regarded as the most taxonomically difficult in the genus and the Pondweed family (Haynes, 1974; Kaplan & Stepanek, 2003; Les et al., 2009). Over the past several decades it has been variously classified as a species, subspecies or variety in major reference works (Potamogeton gemmiparus (J.W. Robbins) J.W. Robbins ex Morong; L. subsp. gemmiparus (J.W. Robbins) Haynes & Hellquist; Potamogeton pusillus L. var. gemmiparus J.W. Robbins). In a phylogenetic study of the complex, Les et al. (2009) verified it as a distinct entity but proposed naming it a subspecies of the widespread Berchtoldt’s pondweed, Fieber ssp. gemmiparus (J. W. Robbins) D. Les & N. P. Tippery. In fact, a petition to use this name has been made and will likely be formally adopted in the next iteration of the State rare species list (initially slated to appear in 2020 but delayed). A later study examining type collections (Kaplan & Reveal, 2013) however reaffirmed the species as Potamogeton gemmiparus (J.W. Robbins) Morong. Taxonomic analyses notwithstanding, Capillary pondweed remains a distinct and undeniably rare taxon, despite its close physical similarity to Berchtold’s pondweed (A. Haines, pers. com.).

While for the sake of simplicity and consistency the name P. gemmiparus is used throughout this report, it is worth noting that confusion ensues when the enduring synonymy among three pusilloid species (P. gemmiparus, P. berchtoldii and P. pusillus) and their subtaxa shows up among lists, reports and collections made by different workers over the botanical history of QL. This situation is exacerbated by lack of clear attribution on some specimens. A recent letter by G. Bugbee (2019) reports that six “questionable” pondweed specimens collected at QL in 2019 by CAES personnel were determined as P. berchtoldii by pondweed authority C. Barre Hellquist, who also confirmed the original collections of P. gemmiparus in 2004-2005 (R. Capers, pers. com.). Scans of these specimens show that neither set bears annotation labels, which are traditionally used as permanent notation for difficult or critical determinations. Whether this report was aimed at casting doubt on the earlier determinations of P. gemmiparus, or if it should merely be interpreted as evidence that both Berchtold’s pondweed (P. berchtoldii, syn. P. pusillus var. tenuissimus) and Capillary pondweed (the species or subspecies) may be present at QL is not clear, since no further explanation is offered. Barring future inquiry this will remain an open question (see Recommendations).

Findings

This survey yielded information of direct as well as more broad applicability, which can be summarized as follows:

1) Despite careful searching, including all previously marked locations and seemingly appropriate habitat at northern and southern ends of the lake, the presence of neither target species could be confirmed. Failure to locate them is not an altogether surprising result, but rather than clarifying the matter raises further questions about the status of these species.

2) No other heretofore unreported state-listed species were identified in the course of the survey. However, several species in plant groups under-represented in previous CAES surveys, e.g., sedges, were noted, mainly in the extensive wetlands at the south end of the lake. This signifies some bias and/or incompleteness on the part of previous surveys, and suggests a need for additional inventory work, since if any such species exist they might also be at risk from proposed herbicidal control measures.

3) A total of 153 taxa were recorded within the lake and along its margins (Appendix 1). Accordance between this list and those of earlier surveys offers reciprocal affirmation of their accuracy and the continued presence of many species. While some plants were only identifiable to genus level, due to late timing or other limitations, the fact that 153 taxa were compiled within such a brief timespan implies that QL supports a still higher level of overall floristic richness. While water bodies such as QL do not constitute a critical habitat type as formally defined at the state level (CTECO, 2011), this richness is noteworthy and would seem to indicate special environmental conditions. The overall floristic composition of the lake, including the possibility of additional notable species, merits further investigation.

Data adequacy and ecological considerations

Correct identification of both native non-native species is a crucial aspect of invasive management (Hellquist, 1993; Moody, Les & DiTomaso, 2008; Bugbee et al. 2012). Identifying all constituent species is equally critical, given that control actions have the potential for wider ranging, unforeseen outcomes (Hellquist, 1993). Hence under-inventory can be as troublesome as misidentification in suggesting control strategies that are misdirected or have unaccounted-for consequences on non-target organisms, which conceivably range from subtle effects such as reduced population numbers or vigor to die-off of rare or sensitive taxa. Completeness can be an elusive achievement however when detection and identification in certain plant groups are fraught with technical and logistical challenges.

While it is fair to trust that most plants recorded at QL over the years have been correctly identified, the pusilloid pondweeds should be viewed with circumspection. Discounting issues of synonymy and taxonomic changes, as previously noted, a presumption of correct identification would mean that P. gemmiparus, P. spirillus, and P. berchtoldii are or were all present. Although this is not implausible, the fact that the three were never recorded in a single year or survey makes it curious. Variable abundance, spatially and temporally, could be a contributing factor to low detectability or infrequent collection. Naturally wide fluctuations in population numbers from year to year at individual sites has been noted by C.B. Hellquist in Potamogeton ogdeni as well as species of the pusilloid pondweeds that freely produce fruits and turions (Hellquist and Mertinooke-Jongkind, 2002). The only ways to address such variability would be to increase the frequency of search efforts, or to assume that species are present throughout the lake. The latter however would probably not be a sound assumption at this time, nor likely acceptable from a town or state regulatory standpoint. On the other hand, since lack of evidence of a species’ presence does not prove its absence, fail-to-find results should not be regarded as indicative of extirpation. If anything, such results should encourage further surveying and a more cautious approach to vegetation control.

Status assessment and discussion of threats

The first and most essential question posed by the NDDB review letter is whether or not the two state-listed species are extant at QL. The second, more implicit question is to what extent has past lake management affected these populations. Neither is easily resolved, especially considering the paucity of data for Capillary pondweed, which was recorded only inside a two-year period--during which time its status was not assessed--and conversely, the long history of observations of Water-marigold, which date back to 1906 (CT DEEP, unpublished data). The latter’s recent absence is difficult to account for, since it was noted in the past as “plentiful” (Eames,1934) and was plotted at over 20 sub-locations as recently as 2015.

Despite the late timing and modest amount of planning and resources afforded this survey, there was reasonable expectation that intensified focus together with better penetration into the lower end of the lake would yield rediscovery of one or both species. Failure to find either, which corroborates other recent survey findings (Bugbee, 2019; CAES, 2018), may be attributable wholly or partly to the afore- mentioned survey shortcomings, but might involve other factors, such as natural population variability; it could also signify disappearance or a sharp decline. Whatever the cause, implications of this finding boil down to two possibilities: 1) one or both species are extant but eluding detection; 2) one or both species are no longer extant. Although it would be premature to accept the second as fact, its possibility alone clearly invokes the question of causation. It is worth noting that and raking/harvesting are not only the likeliest unnatural threats to these species’ survival, but their use may also seriously impede detectability, and thereby hinder better understanding of the species’ status.

Aquatic vegetation ecology is an evolving science with an extensive literature, much of it applied to alien species and their control (see Literature cited). While this brief report does not bear an exhaustive review, the apparent connections between the history of herbicide treatments and recent survey findings at QL demand some discussion in light of this science. Three themes--the selectivity of herbicides used in control, long-term efficacy of herbicide treatments, and scarcity of explicit inclusion of rare species in most studies of non-target effects--hold particular relevance.

Much of the literature, notably older studies, attests that herbicide treatments cause little or no significant harm to native aquatic communities, although it is critical to note that typically this is meant in regard to macrophyte flora overall, rather than individual plant species. Some further suggest that selective use of herbicides can increase or effectively restore aquatic plant diversity by greatly reducing alien species domination (Harman, Hingula & McNamara, 2005). However, other studies point out that not only are few treatments capable of long-term elimination of a dominant species, but that substantial injury to and overall declines in non-target vegetation occur regularly (Getsinger et al, 2008; Mikulyuk et al., 2020). This has caused heightened concern in the native plant rich regions such as the upper Midwest and Northeast (Getsinger et al, 2008). The seeming disparity among these findings probably relates to differences in the aims, methods, and loci of the underlying studies, but also reflects a growing body of knowledge and awareness of pitfalls. Nonetheless, interest in controlling invasive aquatics through herbicide application remains high, largely out of interest in controlling “nuisance aquatic vegetation”, although this term is often used loosely and perhaps without clear justification (Verhofstad & Baker, 2019).

It should be noted that while declines in native macrophyte assemblages are frequently mentioned as being due to alien invasions, displacement effects have rarely been documented in particular species or species combinations. In specific regard to Eurasian milfoil, while some research suggests that it along with whole lake herbicide treatment can reduce native plant species, the data needed to compare the scale of negative effects do not exist (Mikulyuk et al., 2020). Kujawa et al (2017) suggested that in some cases control of Eurasian milfoil may be more detrimental to native communities than the plant itself. One study examining dense Eurasian watermilfoil beds found that a number of native species, including several pondweeds were able to persist measurably under dense milfoil canopies (Madsen, 1994). Other researchers have also noted the ability of pondweeds to coexist (Hellquist & Pike, 2004; Robert Capers, pers. com.).

An even smaller number of studies directly address the risks of herbicide use in terms of loss or decline of aquatic plant species of conservation concern. One of the few species-specific papers available on the subject, which actually used plant material from QL, concluded that sensitivity of Water-marigold to fluridone precludes its use for selective control for Cabomba populations in lakes where the former is present and must be protected (Nelson, Stewart & Getsinger, 2002). Other publications advise that herbicide use is at least incompatible with rare pondweed species, and may possibly eliminate them from water bodies (Hellquist & Pike, 2004; NESHP, 2015). Mudge (2013) found that two pondweeds tested on certain herbicide and combination treatments both showed significant sensitivity, and suggested that other native pondweeds could be similarly impacted.

In summary, my reading of the literature leads to two main points: 1) need for control may be of lesser urgency than sometimes called for, at least on the grounds of rare species management protection; 2) concerns cited in several publications seem to advocate that a cautious rather than aggressive, interventional approach to herbicidal treatment be followed.

Lastly, it should be stressed that not only is use of chemicals to control aquatic plants in Connecticut strictly governed by state law (CT DEEP, 2014), but the Connecticut Endangered Species Act affirms that state agencies responsible for initiating or recommending actions in aquatic habitats that may significantly affect the environment—which includes CAES--bear accountability for taking “all reasonable measures to mitigate any adverse impacts of such actions on endangered or threatened species or essential habitat” (Sec. 26-310). Since DEEP Pesticide Management Program relies on consent from Wildlife Division in cases involving endangered or threatened species (CT DEEP, 2014), a permit application for any water body supporting such species that lacks provisions to protect them can be denied on such basis. For these and other reasons offered in the report, the two rare plant occurrences at QL, especially Capillary pondweed (State Endangered), seem to warrant foremost consideration in current permitting decisions and future site planning.

Recommendations

1) Additional searching/inventory work: Although this survey was carefully executed, because it was confined to a brief late summer effort, faced real-time limitations, and was guided by earlier information that in many respects is incomplete and at this point out-of-date, its findings should not be interpreted as conclusive. Rather, it should serve as impetus for further fieldwork that is (a) more strategically timed, i.e., starting no later than early June, (b) focuses more strictly on rare species than previous CAES surveys, (c) employs methods that better suited to the task of detecting plants in low abundance than this effort or those of CAES. While the two state-listed species would again be the prime foci of such work, it should include all vascular plant groups and extend over as much of the lake and an entire growing season as available time, resources and other factors allow. Populations of any state-listed species identified in the process should be fully detailed, meaning mapped and delineated, photographed and/or vouchered, and assessed to the highest level of precision possible, using standard NDDB reporting forms and/or data tables suited for this purpose. Locations should be field marked for future reference if at all feasible. More comprehensive level of searching than realizable through the transect sampling approach used by CAES, such as point-intercept method based on a fine-scale grid (Madsen and Werzal, 2018), should be contemplated. Finally, because small, fine-leaved plants are quit prone to being overlooked and missed by boat-based sampling (Capers, 2000; R. Capers, pers. com.), use of techniques such as snorkeling/ scuba, underwater camera or DNA sampling might also bear consideration. A plan outlining the costs/benefits of possible survey methods (which exceeded the scope of this report) should be developed prior to such an effort, which should be undertaken in 2021 or at the soonest possible time.

2) Species protection: I strongly recommend at least a provisional moratorium on raking and other harvesting—which I witnessed while surveying--to avert the confounding effect of suppression via ongoing removal of the plant species that are being searched for. This is equivalent to putting a stay on mowing, as is routinely done during terrestrial site surveys. Closure or cutbacks in traffic at the state boat launch during survey periods might also be advisable. Enacting such commonsense measures offers not only greater likelihood of discovery but also enhanced population metrics such as number of flowering stems. If plants of either species end up being found, no-rake buffer zones on the order of 10-meter radius should be established concurrently at the marked locations, and be regularly (e.g., annually) checked thereafter through a program of monitoring. Creating such exclusionary safe zones, especially proactively, might be a hard sell to residents, and in that sense a less than practical solution. However, it would offer the best chance at collecting current and useful data on two species occurrences whose status might otherwise remain indefinitely undeterminable.

3) Collections/herbarium research: An effort should be made to resolve vagueness surrounding identity of some Capillary pondweed specimens. The most effective solution would be to assemble all known collections of pusilloid (Sect. Pusilli) taxa from QL, which reside in four herbaria (UConn, CAES, NEBC and Gray [the latter two at Harvard Univ.]), for collective review by one or more experts. The results could be documented simply by affixing dated annotation labels, as was done by C.B. Hellquist on several pre-2000 specimens at CONN (though notably not on more recent sheets). Because none of these herbaria have been publicly accessible nor are they likely to be anytime soon due to the ongoing COVID crisis, the specimens themselves (rather than scans) would have to be made available on loan. This would obviously require cooperation between institutions and botanical expert(s). Responsibility for this effort could be borne jointly by CAES, UConn, and CT-DEEP, in the interest of improving the taxonomic integrity of the collections as a whole. This would seem justified by the conservation significance of this species. Sarah Taylor, Collections Manager at UConn (pers. com.), has expressed interest in facilitating this.

4) Reevaluation of invasives species management priorities and objectives: Current invasive aquatic plant management practices and objectives at QL bear renewed and closer examination, in my judgement. While control of invasive plants surely has merits, including benefits to native species, the conventional and somewhat reactive methods used in past treatments also carry inherent risks to non-target organisms. When these risks run as high as extirpation of one of only a handful of populations of a regionally rare species in the state, it must be recognized that decision-making affecting resources at the state level supersedes concerns at the local or site level. Moreover, because eradication of Eurasian milfoil or Cabomba, the worst of the invasive species at QL, are almost certainly not feasible goals, the need for re- application will likely arise again in the near future, once again triggering the review process that induced this survey, as has transpired for twenty years. Following the principle of primum non nocere (“first do no harm”), any control work should be deferred until there is definitive clarification on the status of these two species. A period of at least one but preferably two years should be allowed to develop and execute a plan to sufficiently address this need. Thereafter, a more holistic management scheme, which features not only control but prevention and education measures, as recommended in part by Bugbee (2019), should be pursued.

Acknowledgements

Background information and guidance used both in the survey and preparation of this report were kindly provided by the following: Kevin Magee, Town of Guilford; Dr. Robert Capers and Dr. Donald Les, University of Connecticut (retired); Dr. C. Barre Hellquist, College of Liberal Arts; Micah Jasny and Arthur Haines, Native Plant Trust; Karen Zyko and Charles Lee, Connecticut Department of Environmental Conservation; Dr. Sarah Taylor, University of Connecticut.

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Figure 1. Aerial image showing GPS-recorded paths and extent of surveys (orange, blue and red lines) in relation to lakeshore and features. A portion of the shore was not covered (see text).

Figure 2. Profusion of submersed leaves (green) and short emergent flowering stems (small white structures) of Carolina fanwort (Cabomba caroliniana) along eastern edge of lower end of the lk

Figure 3. Surface view of a narrow section of water column showing an admixture of at least four species, highlighting the need for close and careful survey due to the dense overlapping of l

Appendix 1.

Cumulative list of vascular plant species observed at Quonnipaug Lake, Guilford [Source: Collections, field notes and photographs, C.R. Mangels, August 2020]

Species name1 Common name2

Acer rubrum Red maple Acer saccharum Sugar maple Agrostis species Bentgrass Alnus species Alder Amelanchier species Shadbush Ambrosia artemisiifolia Common ragweed Andropogon virginicus Broomsedge bluestem Apios americana Common ground-nut Artemisia vulgaris * Mugwort Asclepias incarnata Swamp milkweed Asplenium platyneuron Ebony spleenwort Athyrium angustum Northern lady fern Berberis thunbergii * Japanese barberry Betula allegheniensis Yellow birch Betula lenta Black birch Betula papyrifera Paper birch Betula populifolia Gray birch Bidens cernua Nodding beggar-ticks Bidens frondosa Devils’ beggar-ticks Boehmeria cylindrica False-nettle Brasenia schreberi Water-shield Cabomba caroliniana * Carolina fanwort Calystegia sepium Hedge false bindweed Carex communis Thin-leaved sedge Carex comosa Bearded sedge Carex gynandra Nodding sedge Carex lurida Sallow sedge Carex species Sedges (unidentified) Carex stricta Tussock sedge Carya ovata Shagbark hickory Catalpa species* Catalpa Celastrus orbiculatus * Oriental bittersweet Cephalanthus occidentalis Common buttonbush Ceratophyllum species Common hornwort Chelone glabra White turtlehead Cicuta bulbifera Bulblet-bearing water-hemlock Clethra alnifolia Coastal sweet-pepperbush Cuscuta ?cephalanthi Buttonbush dodder Cyperus diandrus Umbrella flatsedge Cyperus erythrorhizos Red-root flatsedge Cyperus lupulinus Great Plains flatsedge Cyperus strigosus Straw-colored flatsedge Cystopteris ?tenuis Fragile fern Decodon verticillatus Swamp-loosestrife Dichanthelium acuminatum Hairy rosette-panicgrass Dichanthelium clandestinum Deer-tongue rosette-panicgrass Digitaria sanguinalis * Crabgrass Dulichium arundinaceum Three-way sedge Echinochloa species Barnyard grass Elaeagnus umbellata * Autumn olive Eleocharis ?acicularis Needle spikerush Eleocharis flavescens Yellow spikerush Eleocharis obtusa Blunt spikerush Elodea nuttallii Free-flowered waterweed Epilobium species Willow-herb Eragrostis ?capillaris Lace lovegrass Eragrostis spectabilis Purple lovegrass Erigeron canadensis Canada fleabane Euphorbia maculata Spotted sandmat Eupatorium perfoliatum Boneset thoroughwort Eurybia divaricata White wood-aster Eutrochium maculatum Spotted Joe-Pye weed Fagus grandifolia American beech Fallopia japonica * Japanese knotweed Fallopia scandens Climbing bindweed Fimbristylis autumnalis Slender fimbry Forsythia species Forsythia Fraxinus americana White ash Fraxinus pensylvanica Green ash Froelichia gracilis * Cotton-weed Galium mollugo * White bedstraw Galium palustre Marsh bedstraw Hamamelis virginiana Witch-hazel Hedera helix * English ivy Helianthus divaricatus Woodland sunflower Hemerocallis species * Day-lily Hibiscus moscheutos Swamp rose-mallow Hosta species * Plantain-lily Hypericum boreale Northern St. John’s-wort Hypericum mutilum Dwarf St. John’s-wort Impatiens capensis Jewelweed Ilex verticillata Common winterberry Iris pseudacorus * Yellow iris Iris ?versicolor Blue iris Juncus acuminatus Sharp-fruited rush Juncus canadensis Canada rush Juncus species Rush Juniperus virginiana Eastern red cedar Kalmia latifolia American-laurel Lactuca serriola * Prickly lettuce Lactuca species Lettuce Lemna minor Common duckweed Leersia oryzoides Rice cut-grass Leersia virginica White cut grass Ligustrum species * Privet Linaria vulgaris * Butter-and-eggs toadflax Lindera benzoin Northern spicebush Lindernia dubia var. dubia Yellow-seeded false-pimpernel Liriodendron tulipifera Tuliptree Lonicera japonica * Japanese honeysuckle Lotus corniculatus * Garden bird’s-foot trefoil Ludwigia palustris Common water-primrose Lycopus ?americanus American water-horehound Lysimachia terrestris Swamp yellow-loosestrife Lythrum salicaria * Purple loosestrife Mentha species * Mint Mollugo verticillata * Carpetweed Myosotis scorpioides * Water forget-me-not Myriophyllum heterophyllum * Variable-leaved water-milfoil Myriophyllum spicatum * Eurasian water-milfoil Nuphar variegata Yellow pond-lily canadensis Oldfield-toadflax Nymphaea odorata White water-lily Nyssa sylvatica Black-gum Oenothera species Evening-primrose Onoclea sensibilis Sensitive fern Osmunda cinnamomea Cinnamon fern Osmunda regalis Royal fern Parthenocissus species Virginia-creeper Pellaea atropurpurea Purple cliff-brake Peltandra virginica Green arrow-arum Penthorum sedoides Ditch stonecrop amphibia Water smartweed Persicaria hydropiperoides False water-pepper smartweed Persicaria longiseta * Oriental lady’s-thumb smartweed Persicaria maculosa * Lady’s-thumb smartweed Persicaria punctata Dotted smartweed Persicaria sagittata Arrow-leaved tearthumb Phragmites australis * Common reed Pinus strobus Eastern white pine Plantago lanceolata * English plantain Platanus occidentalis American sycamore Poa compressa * Flat-stemmed blue grass Polypodium species Polypody Pontederia cordata Pickerelweed Populus deltoides Cottonwood Potamogeton amplifolius Big-leaf pondweed Potamogeton crispus * Curly pondweed Potamogeton foliosus Leafy pondweed Floating pondweed Potamogeton robbinsii Robbins’ pondweed Potamogeton zosteriformis Flat-stem pondweed Proserpinaca palustris Marsh mermaid-weed Prunella vulgaris * Self-heal Prunus serotina Black cherry Pyrus species * Pear Quercus alba White oak Quercus montana Mountain chestnut oak Quercus rubra Northern red oak Quercus velutina Black oak Rhododendron species Azalea Rhododendron viscosum Clammy azalea Rhus hirta Staghorn sumac Rosa multiflora * Multiflora rose Rosa palustris Swamp rose Rubus phoenicolasius * Wineberry Sagittaria engelmanniana Engelmann’s arrowhead Sagittaria ?graminea Grass-leaved arrowhead Salix ?discolor Pussy willow Salix eriocephala Heart-leaved willow Salix nigra Black willow Sambucus nigra ssp. canadensis Black elderberry Sassafras albidum Sassafras Schoenoplectus tabernaemontani Three-square bulrush Scirpus cyperinus Common woolsedge Scirpus ?hattorianus Mosquito bulrush Scutellaria lateriflora Mad dog skullcap Sedum species * Stonecrop Smilax rotundifolia Roundleaf greenbrier Solanum dulcamara * Climbing nightshade Solidago caesia Bluestem goldenrod Solidago canadensis Canada goldenrod Solidago nemoralis Gray goldenrod Sparganium species Bur-reed Spirodela polyrrhiza Common duck-meal Swida amomum Silky dogwood Symphyotrichum lanceolatum Lance-leaved American aster Symphyotrichum species American-asters (unidentified) Symplocarpus foetidus Skunk cabbage Thelypteris palustris Marsh fern Thelypteris noveboracensis New York fern Toxicodendron radicans Poison ivy Triadenum virginicum Virginia marsh St. John’s-wort Tsuga canadensis Eastern hemlock Typha angustifolia Narrow-leaved cat-tail Ulmus americana American elm Utricularia gibba Creeping bladderwort Utricularia species Bladderwort (unidentified) Vaccinium corymbosum Highbush blueberry Vallisneria americana Tape-grass Vernonia noveboracensis New York ironweed Viburnum acerifolium Nannyberry Viburnum nudum var. cassinoides Withe-rod Viburnum dentatum Smooth arrowwood Vitis riparia River grape Vitis ?labrusca Fox grape Wisteria species * Wisteria Wolffia brasiliensis Brazilian water-meal

∑ = 198 species

(?) Denotes a tentative species identification (†) Denotes a species of conservation concern in Connecticut (CT-DEEP, 2015). See report for details (*) Denotes species considered alien to Connecticut (Dreyer, Jones, et al., 2014) Nomenclature follows Haines (2011) and/or Flora North America (1993+) Common names follow Haines (2011) and/or Go Botany (https://gobotany.nativeplanttrust.org)