J. Haltori Bot. Lab. No. 74: 235-248 (Nov. 1993)

NEW LATE-PLEISTOCENE ASSEMBLAGES FROM NEW ENGLAND, U.S.A., AND THEIR BEARING ON THE MIGRATIONAL HISTORY OF THE NORTH AMERICAN MOSS FLORA

1 NORTON G. MILLER

ABSTRACT. Fifty-five species of , including two fossils determinable only to , are reported from deposits associated with Lake Hitchcock, which occupied a major part of the Connecticut River Valley during the late Pleistocene. The Matianuck Avenue moss assemblage (from Windsor, Connecticut) is about 13,500 yr B.P., whereas the age of mosses from the Canoe Brook site (from Dummerston, Vermont) is 12,350 yr B.P. Both are AMS ages of Sa/ix twigs found with the mosses. Vascular macrofossils, the moss assemblages, and pollen spectra from the organic beds indicate an open, floristically tundra-like vegetation in which many species of of present arctic and arctic-alpine distribution grew. The two moss assemblages share many species with the younger late-Pleistocene Columbia Bridge paleobryoflora from 250 km northward in the Connecticut Valley, indicating that a high degree of floristic similarity existed among sites in western New England that date to the period 13,500 to 11,500 yr B.P., although the tundra-like vegetation at the southern sites had given way to open boreal woodland by 11,500 yr B.P. The moss assemblages contain species that today are absent from New England but occur as disjuncts in the Gulf of St. Lawrence region and otherwise in arctic or arctic-alpine areas to the north. The fossils demonstrate how widespread these and other mosses were on glaciated surfaces south of areas to which they are now restricted. Some of the mosses are thought to indicate survival in ice-bound refugia near the Gulf of St. Lawrence, but late-Pleistocene occurrences in glaciated areas south of that region suggest that migration from sources to the south is an equally plausible explanation.

INTRODUCTION Moss fossils that occur in a variety of depositional settings within glaciated parts of the Northern Hemisphere offer an excellent opportunity to investigate the geograph­ ic origins of northern bryofloras. Discussed here are two assemblages of fossil mosses that I recovered from organic-rich sediments deposited in different parts of the glacial Lake Hitchcock basin, which held a large proglacial water body in much of the Connecticut River Valley of western New England during part of the late Pleistocene (Fig. 1) . The oldest and southernmost assemblage is from sediments in Windsor, Connecticut; the second is from a younger deposit in Dummerston, Vermont. This research complements an analysis of a late-Pleistocene moss florule described as a result of studies near the northern end of the Connecticut Valley at the Columbia Bridge site, Vermont (Miller, 1987). The age of the Columbia Bridge mosses is ea. 11,500 radiocarbon years before the present (yr B.P.). Fossils from these deposits allow

1 Biological Survey, New York State Museum, Albany, NY 12230, U.S.A. 236 J. Hattori Bot. Lab. No. 74 I 9 9 3

72° 70' Quebec

Columbia Bridge 11 .390 ± 115 yr B.P. ( WIS·919) 11 .540 ± 110 yr B.P (WIS-961) Canoe Brook I 12.355 ± 75 yr BP. (GX· 14232) I 12.455 ± 360 yr B.P. (GX - 14780) 12.915 ± 175 yr B.P. (GX - 14781) I 12,350 ± 090 yr B.P. ''I (Beta 53633. CAMS-2667) Ma tianuck Avenue 14.120 ± 90 yr B.P. (Beta-52711) 13.735 ±180 yr B.P. (W-6397) . 13.540 ± 90 yr B.P . (Bela-59094. CAMS· 4875)

Tom Swamp 6 MA

42'

. . - ···.

5 0 100 Kilometer a

5 0 100 Miles r 10•

Fig. 1. Map of western New England showing location of sites described in the text (diamonds), extent of Glacial Lake Hitchcock, and a list of radiocarbon ages for the three organic deposits. N. G. MILLE R: New late-Pleistocene moss assemblages from New England, U.S.A . 237 comparisons to be made among fossil moss assemblages across a distance of 350 km from south to north and over 2,000 years, from 13,500 to 11,500 yr B.P. There has been much controversy about whether the bryoftora of glaciated parts of northeastern North America assembled through migration from refugia near and beyond the southern limit of glaciation or from ones within glaciated terrain, for example, areas that remained ice-free during the late Pleistocene near the Gulf of St. Lawrence and at places in subarctic and arctic Canada. This topic has been reviewed by Belland ( 1987) who cited evidence derived from an analysis of present occurrences of North American mosses that suggests survival and dispersal from ice-free areas in eastern Canada. Geological support for the absence of late-Pleistocene glaciation in some of these areas is also available. However, as Pleistocene bryoftoras have become better known, fossils of species thought of as indicators of ice-free refugia have been discovered in glacial deposits, documenting that these mosses grew on surfaces that had been glaciated during the late Pleistocene. While such occurrences do not disprove the existence of northern ice-bound refugia, they indicate the dispersal, establishment, and migratory potentials of moss species represented by the fossils. Therefore, the ages and geographic distribution of the fossils provide a way to evaluate hypotheses about the geographic origins and migrational histories of northern mosses that is independent of interpretations based upon present-day distribution patterns.

GEOLOGICAL AND PALEOBOTANICAL SETTINGS Paleobryological data from the Matianuck A venue and Canoe Brook sites are presented in this paper. A brief description of each site and its geological context follows, as do summaries of the results of pollen and vascular plant macrofossil analyses of the sediments that yielded the moss fossils. Matianuck Avenue Site, Windsor, Connecticut (Fig. l ). Road construction uncov­ ered varved sediments of glacial Lake Hitchcock topped by ea. 2.5 m of fine sand and silt beds. Near the bottom of these beds plant detritus occurred in association with beds of fine sand (Stone & Ashley, 1992). Bulk samples of the organic sediment yielded radiocarbon ages of 14,120 ± 90 and 13,735 ± 180 yr B.P. (Stone & Ashley, 1992; and J. Stone, personal communication). A small (0.01 g dry weight) Sa/ix twig ( determina­ tion probable) dated by Accelerator Mass Spectrometry (AMS) was 13,540 ± 90 yr B.P. (Beta-59094, CAMS-4875). The oldest age is probably unreliable (J. Stone, pers. comm.). The upper fine sand and silt beds are interpreted as having been deposited distally to a delta built into Lake Hitchcock when the dam that held back the Jake was breached. Canoe Brook Site, Dummerston, Vermont (Fig. 1). Ridge and Larsen (1990) in their studies into the New England varve chrono1ogy of Antevs described a 21 -m-high exposure of Lake Hitchcock varves, near the top of which were discontinuous 1- cm-thick organic beds containing plant fossils. I sampled in May 1992 the organic bed that corresponds to couplet 463 and those just above and below it. Ridge and Larsen reported the age of the organic beds in the upper couplets as 12,355 ± 75 , 12,455 ± 360, and 12,915 ± 175 yr B.P., with the oldest age treated as problematic. A 0.065 g twig of 238 J. Hattori Bot. Lab. No. 74 I 9 9 3

Sa/ix (dry weight) obtained from my new samples (varve couplet 463) was 12,350 ± 90 yr B.P. (Beta-53633, CAMS-2667), providing support for this interpretation. The organic-rich beds probably were deposited during periodic floods that carried terrestrial plant material and other sediments into Lake Hitchcock from the adjacent Canoe Brook Valley (Ridge & Larsen, 1990). The two sets of radiocarbon ages (ea. 13,500 vs. ea. 12,350 yr B.P.) indicate differences in the history of Lake Hitchcock, with a northern remnant of the lake probably lasting longer than an older and larger lake in the southern and northern parts of the Connecticut Valley, which drained at ea. 13,500 yr B.P. (Stone & Ashley, 1992). The composition of pollen spectra from organic silts associated with the plant beds are as follows. Matianuck Avenue (as I reported in Stone & Ashley, 1992), two samples. Herbs and shrubs: grass (41%, 41 %), sedge (14%, 15 % ), Caryophyllaceae (4%, 4% ), Thalictrum (4%, 2%), Compositae (3 %, 3% ), Dryas (0.3%, 1.4%), Oxyria (0.8%, 3%), Armeria (0.4%, 0.6% ), other herbs (0.6%, !% ); Sa/ix (4% , 5%), Alnus (2%, 2%). Trees: pine (19%, 14%), spruce (5 %, 4%), oak (1 % , 2%), birch (1 %, 1%), and small amounts of hemlock, sugar maple, ironwood, elm, ash, basswood, and hickory (each less than 0.5%). Canoe Brook, one sample. Herbs and shrubs: sedge (34% ), grass (7% ), Caryophyllaceae (6% ), Oxyria (4%), Compo­ sitae (4%), Dryas (1.5%), other herbs (3.6% ); Sa/ix (3 %), Alnus (1 % ). Trees: pine (22% ), spruce (11 %), oak (2%), birch (1 % ), ironwood (1 % ), and small amounts of ash and arbor vitae/juniper-type (0.2%). Herb pollen is 71 % and 67 % of the totals in the two Matianuck samples (vs. 29 and 33 % for all tree and shrub pollen) and 59% (vs. 41% for tree and shrub pollen) in the Canoe Brook sample. Such high percentages of herb pollen are characteristic of treeless or sparsely forested landscapes at the present time, indicating that at 13,500 and 12,350 years ago surfaces near the fossil beds supported an open, tundra-like vegetation that consisted principally of herbs and other plants of low stature. The floristic composition of this vegetation is further defined by the vascular plant macrofossils (and by the mosses; see below) that have been recovered from the organic bed. While I will treat the plant macrofossils (and the pollen) in other papers, some of the more significant finds are listed here. The plant beds at both sites contain abundant leaves of Dryas integrifolia Yahl and Sa/ix herbacea L. and some of S. reticulata L.; fruits of Oxyria digyna (L.) Hill, Sibbaldia procumbens L., Potentil/a, and Cyperaceae (both Carex spp. and Scirpus); seeds of a number of different Caryophyllaceae, including Silene acaulis L.; and calyces of Armeria maritima Willd. Identified from Matianuck are leaf-bearing twigs of Harrimanella hypnoides (L.) Coville and achenes of Thalictrum alpinum L., while only from Canoe Brook are a capsule wall of Draba and seeds of Parnassia sp. A large series of additional plant fossils from both sites are under study, and more species will be identified. Many of these plants are rare arctic-alpine species that grow in the open on the highest New England (and New York) mountains and at suitable alpine, subarctic, and arctic sites to the north. N. G. MILLER: New late-Pleistocene moss assemblages from New England, U.S.A. 239

METHODS Access to fresh exposures of sediment allowed samples of large volume to be collected. One block of about 4000 cc, containing several thin plant beds, was collected at the Matianuck A venue site; several blocks totalling 9600 cc, centering on couplet 463, were removed from the Canoe Brook outcrop. The samples were wrapped in plastic or aluminum foil and kept under refrigeration until they were disaggregated in the laboratory. Since the plant fossils were associated with sand and silt beds and not with clay, the sediment blocks were broken along the bedding planes to allow the clay beds to be removed and discarded. Samples of sand and silt were put in a 250-µm-mesh sieve, through which smaller sediments were washed with a gentle stream of tap water and discarded. When necessary, the sieve residues were further cleaned by heating them to 70°C in water or 2.5 % Na2C03, and the samples were again washed in tap water, using a 250-µm-mesh sieve to retain the fossils. The volume of sieve residues were 822 cc (Matianuck Avenue; over half of this volume was muscovite flakes) and 492 cc (Canoe Brook; sample largely organic). Residue subsamples were searched for moss fossils at 15 X . The fossils were sorted on the basis of characteristics seen through a dissecting microscope, and a sample of the fossils in each category was dissected (or if necessary sectioned) and mounted in Hoyer's solution for further study at high magnification. I prepared and studied 124 slides of mosses from the Matianuck Avenue deposit and 131 from Canoe Brook. Comparisons were made routinely between the fossils and plants from herbarium specimens. Notes about the fossils and their identifi­ cation are given in the Appendix. The slides have been deposited in the Quaternary Paleobotany Collection of the New York State Museum.

RESULTS AND DISCUSSION The fossil mosses identified from late-Pleistocene sediments at the Matianuck Avenue and Canoe Brook sites are listed in Table 1. Together both sites yielded fossils representing 55 extant species. Six of these were not identified conclusively for reasons of incomplete preservation (e.g., absence of sporophytes (and the character states they provide) or some diagnostic part(s) of the leaves degraded). All of the identifications are based on leafy gametophytes that generally are less than 1 cm long. Some species are represented either in large part or only by buds (Aulacomnium turgidum, Pseudocal/i­ ergon turgescens, Sarmenthypnum sarmentosum) or isolated leaves (Timmia norvegica var. norvegica) , both of which are likely to have functioned as diaspores. Thirteen species (Aulacomnium acuminatum, Barbu/a convoluta, Bartramia ithyphylla, Cinclid­ ium latifo/ium, Cyrtomnium hymenophylloides, Didymodon rigidulus var. icmadophilus, Enca/ypta cf. rhaptocarpa, Hypnum bambergeri, Schistidium apocarpum , Timmia norve­ gica var. norvegica, Torte/la arctica, Tortu/a norvegica, Trichostomum arcticum) are new to the New England late-Pleistocene moss flora. A total of 94 species of mosses are now known as late-Pleistocene fossils in this region on the basis of research published by Anderson et al. (1986, 1990), Argus and Davis (1962), Miller (1987a, b), and Tolonen and Tolonen (1984), 65 of these from the Connecticut River Valley. Others 240 J. Hattori Bot. Lab. No. 74 I 9 9 3

Table 1. Connecticut River Valley Late-Pleistocene moss floras. Fossil occur- rence indicated by a plus sign ( +) when identification is certain or cf. when identifi- cation is probable. Names are those adopted by Anderson et al. ( 1990).

Matianuck Canoe Columbia Avenue, Brook, Bridge, Connecticut se. Vermont ne. Vermont Abietinella abietina + + + Aulacomnium acuminatum + A. palustre + cf. A. turgidum + Barbu/a convoluta + Bartramia ithyphylla + Brachythecium turgidum + + Bryoerythrophyllum recurvirostre + + Bryum pseudotriquetrum + + + Calliergon richardsonii cf. Campylium stellatum + + + Catoscopium nigritum + Ceratodon purpureus + + + Cinclidium latifolium + Cyrtomnium hymenophylloides + Dichodontium pellucidum + cf. Dicranella varia + Didymodon asperifolius + D. rigidulus var. icmadophilus + Distichium sp. + + + Ditrichum jfexicaule + + + Drepanocladus aduncus + + Encalypta alpina cf. cf. + E. procera cf. E. rhaptocarpa cf. cf. Fissidens bryoides + + F. osmundioides + + cf. Hamatocaulis vernicosus + Hygroamblystegium tenax + + + Hygrohypnum luridum + + Hypnum bambergeri + H. lindbergii + H. pratense + H. revolutum + + + H. vaucheri + + Limprichtia revolvens + + + Meesia uliginosa + + + Mnium thomsonii + + Myurella julacea + + + Palustriella commutata + Philonotis fontana + + + N. G. MILLER: New late-Pleistocene moss assemblages from New England, U.S.A. 241

Table I. (continued) Matianuck Canoe Columbia Avenue, Brook, Bridge, Connecticut se. Vermont ne. Vermont Pogonatum urnigerum + + + Pohlia cruda cf. cf. P. sp. + + Polytrichastrum alpinum + Polytrichum juniperinum + + + P. piliferum cf. cf. + Pseudocalliergon turgescens + + + Pseudocrossidium revolutum + Racomitrium canescens + Rhytidium rugosum + Sanionia uncinata + Sarmenthypnum sarmentosum + Schistidium apocarpum + Scorpidium scorpioides + + + Timmia norvegica var. norvegica + + T. norvegica var. excurrens + Tomenthypnum nitens + + Tortella arctica + T. fragilis + + + T. inclinata cf. + Tortu/a norvegica + + T. rura/is + cf. Trichostomum arcticum + + T. crispulum + Warnstorfia exannulata + Weissia controversa cf. cf. Total 43 36 45

are from Tom Swamp, Massachusetts, which is just east of the Valley (Fig. 1 ). Both fossil beds consist almost entirely of terrestrial plant material that was brought to the Hitchcock Lake basin by inflowing streams. Plant fragments from different communities thereby become associated and eventually deposited together with sand and silt. Such mixed assemblages are characteristically rich in the number of species represented by fossils. For the Matianuck and Canoe Bridge organic beds the low frequency of moss fossils of different kinds and their subordinate abundance relative to other plant remains in the samples ( < 1% of the residues) make it impossible to infer quantitative relationships among the terrestrial communities that are indicated by the fossils. Nevertheless, some general conclusions can be drawn about the microhabitats and the plant communities in which the mosses grew. All of the species indicate open 242 J. Hattori Bot. Lab. No. 74 I 9 9 3

Fig. 2. Illustrations of fossil mosses from the Matianuck and Canoe Bridge sites. A-C, Cinclidium latifolium. A, apex of plant, largest leaf convex (scale bar a); B, detail at insertion of two leaves (d); C, cells at leaf apex, note diagonal "rows" of cells (c). D--0, Aulacomnium turgidum. D, apex of plant (a); E, leaves (b); F, cells at leaf apex (c); G, cells at mid-leaf (c). H- M, Timmia norvegica. H, leaf (a); I, dorsal (lower) surface of costa near leaf apex, showing papillae (c); J, cells of limb at mid-leaf (c); K, cells along upper leaf margin, ventral (upper) side (c); L, cells at base of sheath, thin-walled at bottom (line of breakage?) (c); M, cross-section of limb at mid-leaf (c). N- P, Hypnum revolutum. N, habit of two plant fragments (a); 0, leaves, margins revolute (f); P, cells at basal angle of leaf (c). N. G. MILLER: New late-Pleistocene moss assemblages from New England, U.S.A. 243 sites that lack a cover of trees or high shrubs. Aquatic species are poorly represented (only Drepanocladus aduncus at Matianuck, but it also can grow in calcareous seeps or wetlands), but more mosses indicative of calcareous seeps or perhaps rich fens are present (Campylium stellatum, Limprichtia revolvens, Pseudocalliergon turgescens, Sco­ rpidium scorpioides, Tomenthypnum nitens). The wetland habitats of Limprichtia revolvens and Scorpidium scorpioides in Sweden have been studied by Kooijman and Hedenas (1991) who reported mean values of various water chemistry parameters for numerous populations of these mosses. Scorpidium scorpioides grew in water with a mean pH of 7.1 (vs. 6.3 for L. revolvens) and more Ca (x = 62.2 mg/I) and HC03 (x = 148 mg/I) ions than found in water associated with L. revolvens (Ca= 3.6, HC03 = 0). These studies are support for the presence of calcium-rich, circumneutral, wet habitats along the shore of Lake Hitch­ cock. Dry calcareous and acidic mineral soils and/or rock are also indicated. Calcicole mosses of dry sites include Abietinella abietina, Barbu/a convoluta, Bryoerythrophyllum recurvirostre, Didymodon rigidulus var. icamadophilus, Hypnum revolutum, Tortu/a norvegica, T. ruralis, and Rhytidium rugosum, whereas Polytrichum juniperinum, P. piliferum, Racomitrium canescens, and others are often found on dry, acid, mineral substrata. Some of these species and others represented in the fossil beds (e.g., Ceratodon purpureus) are often associated with disturbance, and thus can be early successional plants. Species associated with lingering snow beds (e.g., Aulacomnium acuminatum) are also present. I have commented elsewhere on the predominance of calcicole mosses in late­ Pleistocene fossil assemblages and the significance of this observation in understanding the history of northern North American flora (Miller, 1987a). Calcicoles are a major component of fossil assemblages in areas of both acidic and calcareous rock and drift even though in the case of acidic areas calcicoles are not members of the present flora. Thus, calcicoles were widely distributed in the late Pleistocene, whereas they are of more restricted occurrence now. The Matianuck and Canoe Bridge assemblages, which contain numerous calcicole mosses, support this conclusion. They and the Columbia Bridge moss florule represent samples of the late-Pleistocene flora that occurred over a distance of 350km within period of about 2,000 radiocarbon years (13,500-11,500 yr B.P. ). An open barren-ground moss flora rich in calcicoles occurred in western New England during a period of 2,000 years, in fact probably longer in areas closer to the Wisconsinan terminal moraine, although in the southern part of this region trees (poplar, birch, spruce, pine) had begun to increase in abundance prior to 14,000 yr B.P. (Davis & Jacobson, 1985). Many of these moss species are now absent from western New England but occur to the north or are restricted to a few alpine localities in the New England and nearby mountains. The three assemblages, while varying somewhat in species composition, do not differ greatly in present geographic relationships, which is revealed by a comparison between species listed in Table 1 and those enumerated in the Crum and Anderson flora for eastern North America (1981; the northern boundary of the area treated in this 244 J. Hattori Bot. Lab. No. 74 I 9 9 3 flora is the north edge of the Eastern Deciduous Forest, i.e., from the Canadian Maritimes across southern Quebec and Ontario to Minnesota). Nine of the 65 species and varieties are not treated by Crum and Anderson because they occur largely to the north (Cinclidium latifolium, Didymodon rigidulus var. icmadophilus, Encalypta alpina, Pseudocrossidium revolutum, Timmia norvegica vars. norvegica and excurrens, Tortella arctica, Trichostomum arcticum, and T. crispulum; the last is a critical species, and its distribution in North America is not yet fully understood). Another four species (Aulacomnium acuminatum, Didymodon asperifolius, Hypnum bambergeri, Tortu/a norvegica) barely reach the Crum and Anderson area, and five others are rare species in it (A. turgidum, Cyrtomnium hymenophylloides, Hypnum revolutum, Scorpidium turgescens, and Torte/la inclinata). Together the species in these three categories total nearly 30% of the fossil assemblages. Known occurrences through 1970 of two of them, Didymodon asperifolius and Trichostomum arcticum, are mapped by Schofield (1972), and Hedderson and Brassard (1986) presented an updated distribution map for T. arcticum. Schofield ( 1972) considered the mosses members of the high arc tic fioristic element because of their present restriction in North America largely to areas near or north of the Arctic Circle, although they occur also as disjuncts at a few places near the Gulf of St. Lawrence (Hedderson & Brassard, 1986; Belland et al., 1992). The historical geography of disjunct populations of arctic and arctic-alpine bryo­ phytes near the St. Lawrence Gulf continues to elicit much analysis and speculation. The. number of species involved and their geographic affinities suggest the possibility of survival in ice-free areas during the late Pleistocene (Belland, 1987). That may have happened, but eight of the mosses Belland ( 1987) listed as possibly indicative of such a history (Cyrtomnium hymenophylloides, Didymodon asperifolius, D. rigidulus var. icmadophilus, Encalypta alpina, Hypnum bambergeri, Timmia norvegica , Tortella ar­ ctica, Trichostomum arcticum) are now known as fossils from one or more late­ Pleistocene deposits in glaciated New England, 1, 100 km to the southwest. Some of these (D. asperifolius, T. arcticum) have older late-Pleistocene records from the periglacial area of eastern and central North America (Miller, 1992), suggesting a high migratory potential for these species and the existence of edaphic, climatic, and other environmental factors that probably allowed their repeated establishment at different places over a long period of time (at least 7,000 radiocarbon years and perhaps two or three times longer on the basis of present information; Miller, 1992). Thus, the fossil record indicates that a southern source for at least some of the disjuncts in the Gulf of St. Lawrence region is at least as likely an explanation for their migrational history and geographic origin as survival and/or dispersal from ice-bound refugia. The remaining 70% of the fossil assemblages are species that still occur largely within the area treated by Crum and Anderson (1981), although some are rarities. In a floristic sense then, the late-Pleistocene moss flora of New England does not seem to have been greatly different from that of today because so many of the species represented in the fossil assemblages still occur in the region. It may not be possible to develop a simple explanation for the migrational history of this bryoflora, given its size and phytogeographical diversity, but I suggest here, as I have elsewhere (Miller, 1980), N. G. MILLER: New late-Pleistocene moss assemblages from New England, U.S.A. 245

that this similarity in species composition between the periglacial and present moss floras of eastern North America indicates that many (but of course not all) northern and southern (i.e., temperate latitude) floristic elements may have grown together during the late Pleistocene near or on glaciated surfaces close to the southern limit of glaciation. Postglacial time ( 10,000 yr B.P. to the present) saw a loss or restriction in areas of members of the former group and an expansion in range of the latter. A species may be found to deviate from this pattern for different reasons, but as a working hypothesis and a potential generalization it is supported from a growing understanding of the composition and distribution late-Pleistocene bryofloras.

ACKNOWLEDG MENTS Sediment samples used in this study were collected with the help of J.C. Ridge and D. W. Steadman (Canoe Brook) or were sent to me through the courtesy of L. McWeeney and J. R. Stone (Matianuck Avenue). Wood from parts of the twigs dated by AMS was identified by H. A. Alden of the U.S.D.A. Forest Products Laboratory, Madison, Wisconsin. Diana Horton, Gert Mogensen, and Richard Zander named or confirmed the identity of fossils of Encalypta, Cinclidium, and Pottiaceae, respectively. Figures l and 2 are the work of Patricia Kernan and Patricia Eckel, respectively. All of these contributions have added substantially to this paper. This paper is published as Contribution Number 719 of the New York State Science Service.

LITERATURE CITE D Anderson, L. E., H. A. Crum, & W. R. Buck. 1990. List of mosses of North America north of Mexico. Bryologist 93 : 448- 499. Anderson, R. S., R. B. Davis, N. G. Miller, & R. Stuckenrath. 1986. History of late- and post-glacial vegetation and disturbance around Upper South Branch Pond, northern Maine. Canad. Jour. Bot. 64: 1977- 1986. Anderson, R. S., N. G. Miller, R. B. Davis, & R. E. Nelson. 1990. Terrestrial fossils in the marine Presumpscot Formation: implications for late Wisconsinan paleoenvironments and isostatic rebound along the coast of Maine. Canad. Jour. Earth Sci . 27 : 1241 - 1246. Ando, H. 1976 [pub. 1977] . Studies on the genus Hypnum Hedw. (III). Jour. Sci . Hiroshima Univ. B. Bot. 16: 1- 46. Argus, G. W., & M. B. Davis. 1962. Macrofossils from a late-glacial deposit at Cambridge, Massachusetts. Amer. Midi. Nat. 67 : 106- 117. Belland, R. J. 1987. The disjunct moss element of the Gulf of St. Lawrence region: glacial and postglacial dispersal and migrational histories. Jour. Hattori Bot. Lab. 63: 1- 76. Belland, R. J., W. B. Schofield, & T. A. Hedderson. 1992. of Mingan Archipelago National Park Reserve, Quebec: a boreal flora with arctic and alpine components. Canad. Jour. Bot. 70: 2207- 2222. Brassard, G. R. 1979. The moss genus Timmia. I. Introduction, and revision of T. norvegica and allied taxa. Lindbergia 5: 39- 53 . Crum, H. A., & L. E. Anderson. 1981. Mosses of eastern North America. 2 vols. Columbia University Press. New York. 246 J. Hattori Bot. Lab. No. 74 I 9 9 3

Crundwell, A. C., & E. Nyholm. 1963. Notes on the genus Torte/la II. Torte/la arctica. Byologist 66: 184- 191. Davis, R. B., & G. L. Jacobson, Jr. 1985. Late glacial and early Holocene landscapes in northern New England and adjacent areas of Canada. Quat. Res. 23 : 341 - 368. Hedderson, T. A., & G. R. Brassard. 1986. The bryophytes of Nachvak, northern Labrador, with additional records from Saglek. Canad. Jour. Bot. 64: 2028- 2036. Horton, D . G. 1982. A revision of the Encalyptaceae (Musci), with particular reference to the North American taxa. Part I. Jour. Hattori Bot. Lab. 53 : 365- 418. Kooijman, A., & L. Hedenlis. 1991. Differentiation in habitat requirements within the genus Scorpidium, especially between S. revolvens and S. cossonii. Jour. Bryol. 16: 619- 627. Miller, N. G. 1987a. Late Quaternary fossil moss floras of eastern North America: Evidence of major floristic changes during the late Pleistocene-early Holocene transition. Syrup. Biol. Hung. 35 : 343- 360. Miller, N. G. 1987b. Phytogeography and paleoecology of a late-Pleistocene moss assemblage from northern Vermont. Mem. New York Bot. Garden 45: 242- 258. Miller, N. G . 1992. A contribution toward a history of the arctic moss flora. Contrib. Univ. Mich. Herb. 18: 73- 86. Mogensen, G. S. 1973. A revision of the moss genus Cinclidium Sw. (Mniaceae Mitt.). Lindbergia 2: 49- 80. Ridge, J.C., & F. D. Larsen. 1990. Re-evalution of Antevs' New England varve chronology and new radiocarbon dates of sediments from Lake Hitchcock. Bull. Geol. Soc. Amer. 102: 889- 899. Sayre, G . 1952. Key to species of Grimmia in North America. Bryologist 55 : 251 - 259. Schofield, W. B. 1972. Bryology in arctic and boreal North America and Greenland. Canad. Jour. Bot. 50: 1111- 1133. Stone, J. R., & G. M. Ashley. 1992. Ice-wedge casts, pingo scars, and the drainage of Glacial Lake Hitchcock, p. 305- 331. In: Robinson, P., & J.B. Brady (Eds.), 84th New England Intercollegiate Geological Conference. Univ. Massachusetts Dept. Geol. Geog. Contrib. 66. Tolonen, K., & M. Tolonen. 1984. Late-glacial vegetational succession at four coastal sites in northeastern New England: ecological and phytogeographical aspects. Ann. Bot. Fenn. 21 : 59- 77.

Appendix. Identification criteria used for fossils from the Matianuck Avenue and Canoe Brook sites. I. Aulacomnium acuminatum (Lindb. & Amell) Kindb. The fossils consist of one isolated leaf and one plant fragment with four leaves. The leaves are acuminate and revolute to near the apex. Large trigonous corner thickenings are present in the cells of the leaf lamina, producing obvious stellate lumens. Large, thick-walled cells with yellow-brown walls in a buttress-like arrangement occur at the base of most of the leaves. In all these features the fossils compare favorably with reference specimens of A. acuminatum. In fossils of A. palustre (Hedw.) Schwaegr. recovered from the same sediment samples the cell lumens are polygonal or weakly stellate. 2. Bartamia ithyphylla Brid. One well-preserved plant with 21 leaves was recovered. All leaves consist of a clasping base and a narrow conspicuously serrate limb. The characteristic paired papillae of this moss are visible at the ends of adjacent surface cells of the limb. 3. Cinclidium latifolium Lindb. I recovered one plant with four leaves, one of which is convex, N. G . MILLER: New late-Pleistocene moss assemblages from New England, U.S.A. 247

a unique feature of this moss. Some of the leaves are apiculate. The leaf cells are organized in diagonal series, and rows of macronematal initials are discernible on the stem with epi-illumination. These two character states are diagnostic ofCinclidium (Mogensen, 1973). Fig. 2, A- C. 4. Cyrtomnium hymenophyl/oides (Hilb.) Nyh. ex T. Kop. One fragment with five complete or partial leaves, the orientation, shape, and areolation of which compare favorably with herbarium material. 5. Encalypta cf. rhaptocarpa Schwaegr. Numerous well-preserved leafy plants of Encalypta were recovered, and many of these can be referred to E. rhaptocarpa . Calyptrae were also present, but in all cases they are degraded and therefore do not present the features needed for identification (Horton, 1982). The fossils were studied by Diana Horton who wrote (23 March 1993), "I suspect that the majority of your specimens represent E. rhaptocarpa. The well-defined basal lamina! cells and marginal border, the short hair point (often broken) on some of the leaves, and the general shape of the leaves all would fit within the range of variation of E. rhaptocarpa." One calyptra has a spore in the rostrum, but the orientation of the spore prevents observation of its sculpture pattern, thereby precluding identification by this means. 6. Hypnum bambergeri Schimp. Identification based upon one plant fragment that consists of 46 long-acuminate, circinate leaves, which when dissected showed the following diagnostic features: conspicuous groups of cells with thick, orange-brown walls in the alar regions and porose basal cells. 7. H. vaucheri Lesq. Numerous fragments of well-preserved leafy plants are available for evaluation. Conspicious and characteristic groups of quadrate cells are present at both sides of the leaf base. In one slide rounded, isodiametric pseudoparaphyllia are present. (These differ from those of H. cupressiforme Hedw., which is sometimes considered conspecific; see Ando, 1976.) 8. Schistidium apocarpum (Hedw.) Buch & Schimp. in B.S.G., s. /at. One well-preserved plant (upper part only) was readily referred to this moss using Sayre's identification key (1952). The eroded acuminate leaf apices of the fossil lack hair points. The leaves are 1.5 mm or less, and their margins are recurved. 9. Timmia norvegica Zett. var. norvegica. Only isolated leaves of this moss were found, 12 in the Canoe Brook sediments and one from Matianuck Avenue. The leaves are serrate in the upper part, and in some thin-walled cells are visible at the base of the sheath. These probably correspond to the line of dehiscence that causes the leaves to break off the parent plant, from which they can be dispersed. The costa is conspicuously papillose in the abaxial side of the leaf, and adaxial sides of cells of the lamina are bulging mamillose. Cells of the lamina are 14µm wide (average). These features correspond to T. norvegica var. norvegica, using the key and descriptions of Brassard (1979). Fig. 2, H- M. 10. Torte/la arctica (Arnell) Crundw. & Nyh. Two plants were found, one with 10 leaves and three small leafy secondary branches and the other with 35 leaves and three secondary leafy branches. Character states emphasized by Crundwell and Nyholm (1963) are visible in the fossils, viz., elongate, thick-walled, dark-colored basal lamina! cells (these extending up the leaf margins), thinner walled cells near the leaf insertion, and leaf margins not undulate. 11. Tortu/a norvegica (Web.) Wahlenb. ex Lindb. Fossils of this moss were frequent in the Canoe Brook and Matianuck organic sediments. Identification criteria included, acute leaf apices (vs. rounded or obtuse in T. ruralis (Hedw.) Gaertn. et al.), leaf margins revolute for 248 J. Hattori Bot. Lab. No. 74 I 9 9 3

ea. 80 percent of length and plane in upper fifth, costa thinning near leaf apex and sometimes absent, and awn (when preserved) reddish from base to tip. 12. Trichostomum arcticum Kaai. Three plant fragments (with seven, 12, and 14 leaves) were found. The leaves, which are well preserved, present the following diagnostic features: margins plane; marginal cells above the nonpapillose basal lamina! cells convex and crenulate-papillose; papillae simple; cells at the leaf base thin-walled, four to five times longer than broad, and grading into shorter (nearly quadrate), thick-walled, epapillose cells just below where the cells of the leaf begin to show papillae; and long, smooth leaf tips.