. The Canadian field-naturalist. . 1mm Figure I. Achenes of Cyperus flavescens. Tip of Long Point (21 September 1979, Reznicek 5324 and Catling). Grass), Panicum linearifolium (Panic Grass) and Poa compressa (Canada bluegrass). Also present were Carex muhlenbergii (Sedge), Carex pensylvanica (Sedge), Panicum latifolium (Panic Grass) and Pani- cum oligosanthes (Panic Grass). The rooting medium oiCarex nigromarginata had a pH of and included the upper 2 cm of substrate comprised of coarse sand mixed with much organic material. At 5 cm depth the substrate was almost pure sand with a pH of
. The Canadian field-naturalist. . 1mm Figure I. Achenes of Cyperus flavescens. Tip of Long Point (21 September 1979, Reznicek 5324 and Catling). Grass), Panicum linearifolium (Panic Grass) and Poa compressa (Canada bluegrass). Also present were Carex muhlenbergii (Sedge), Carex pensylvanica (Sedge), Panicum latifolium (Panic Grass) and Pani- cum oligosanthes (Panic Grass). The rooting medium oiCarex nigromarginata had a pH of and included the upper 2 cm of substrate comprised of coarse sand mixed with much organic material. At 5 cm depth the substrate was almost pure sand with a pH of The occurrence of Carex nigromarginata on Long Point is of considerable phytogeographical interest. It is a southern and eastern species, occurring north to southern Connecticut (Seymour 1969), southeastern New York (Fernald 1950), eastern and southernmost Pennsylvania (Bright 1930; Jennings 1953), southern Ohio (Braun 1967) west to southernmost Illinois and adjacent Missouri (Mohlenbrock and Ladd, 1978). An isolated station in Crawford County, northwest- ern Pennsylvania, noted by Bright (1930) and Jen- nings (1953), is the closest reported site to the equally isolated Long Point populations but no specimens confirming this occurrence have been found (C. S. Keener in litt.). Gleason and Cronquist (1963), Boivin (1967) and Scoggan (1978) consider Carex emmonsii Dewey, C. artitecta Mack, and C. peckii Howe to be varieties of C. nigromarginata; as var. minor (Boott) Gl., var. muhlenbergii (Gray) Gl., and var. elliptica (Boott) Gl. respectively. Although each of the above taxa has been found in Canada, the more southern C. nigro- marginata s. str. (C. nigromarginata var. nigromargi- nata) is reported here for the first time. While C emmonsii and C. artitecta are very similar and diffi- cult to separate (Voss 1972), C. peckii and C. nigro- marginata s. str. appear more sharply distinct. Carex nigromarginata may be distinguished from other sim- ilar northeastern North American mem
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