Nos and P. perligulata grow in perennially wet or “waterlogged” habitats, often with densely-interwoven vegetation. On Ixtaccihuatl, RJS recalls a large population to have occurred over much of the wet floor of the southeastern glacial circ, forming discrete, low mats to about 20 cm in diameter.7. Poa compressa L., Sp. Pl. 1: 69. 1753. http://species-id.net/wiki/Poa_compressa Fig. 1 F Type: Habitat in Europae and Americae septentrionalis, (lectotype: LINN-87.41!, designated by Soreng 2000: 255). Description. Hermaphroditic. U0126-EtOH site Perennials; extensively rhizomatous, shoots solitary, green or bluish-grey-green; tillers extravaginal (basally cataphyllous), with lateral and downward tending, cataphyllous shoots. Culms 15?0 cm tall, erect, bases usually geniculate, wiry, leafy, strongly compressed, smooth; nodes strongly compressed, 3? nodes usually exerted. Leaf sheaths distinctly compressed, minutely rough; butt sheaths papery, smooth, glabrous; flag leaf sheaths ca. 2? cm long, margins fused 10?0 the length, subequal to its blade; throats and collars smooth or slightly scabrous, glabrous; ligules 1? mm long, abaxially moderately to densely scabrous, upper margin ciliolate, apices obtuse; blades 1.5? mm wide, flat or folded, abaxially smooth, veins slightly expressed, margins scabrous, adaxially lightly scabrous over the veins, apices abruptly prow-tipped; cauline blades subequal; sterile shoot blades like those of the culm. Panicles 2?0 cm long, generally 1/6?/3 as broad as long, erect, contracted or slightly open, linear, lanceoloid to ovoid, often interrupted, sparse to congested, with 15 to 80 spikelets; rachis with mostly 1? branches per node; primary branches erect to ascending, or infrequently spreading, fairly strict, 2? angled, angles distinctly scabrous (at least in part); lateral pedicels 1/5?/3 their spikelet in length, scabrous, prickles moderately coarse; longest branches 0.5? cm, with 1?5 spikelets. Spikelets (2.3?3.5? mm long, laterally compressed; not bulbiferous; grayish, often anthocyanic tinged, not lustrous; florets 3?, hermaphroditic; rachilla internodes terete, mostly less than 1 mm long, smooth to muriculate; glumes lanceolate, subequal, distinctly keeled, keels scabrous; apices acute; lower glumes ca. 2 mm long, 3-veined; upper glumes ca. 2.1 mm long, 3-veined; calluses glabrous or more often webbed; web distinct, hairs short, woolly, sparse; lemmas 2.3?.5 mm long, lanceolate, distinctly keeled, keels and marginal veins short villous proximally, between veins smooth, glabrous, intermediate veins obscure, margins narrowly scarious-hyaline, edges smooth orRobert J. Soreng Paul M. Peterson / PhytoKeys 15: 1?04 (2012)with sparsely scaberulous, apices obtuse to acute; paleas densely scabrous over the keels, between keels smooth. Flowers chasmogamous; lodicules ca. 0.6 mm long, lanceolate, with a subequal lateral lobe in the upper 2/3; anthers 1.3?.8 mm long. Caryopses 1.4?.5 mm long, elliptical in side-view, subtrigonous to subcylindrical in cross-section, brown, shallowly sulcate, hilum 0.2 mm long, oval, grain adherent to the palea. 2n = 35, 42, 49, 50, 56. Distribution. This species is circumboreal in AZD1722 biological activity distribution and in North America it occurs in Canada, USA, and Mexico (Coahuila). Ecology. This strongly rhizomatous, ruderal species occurs in mesic, cool temperate, semi-shaded to open habitats in seasonally soggy soils, sands to clays, both derived from calcareous and igneous substrates. Once established, this specie.Nos and P. perligulata grow in perennially wet or “waterlogged” habitats, often with densely-interwoven vegetation. On Ixtaccihuatl, RJS recalls a large population to have occurred over much of the wet floor of the southeastern glacial circ, forming discrete, low mats to about 20 cm in diameter.7. Poa compressa L., Sp. Pl. 1: 69. 1753. http://species-id.net/wiki/Poa_compressa Fig. 1 F Type: Habitat in Europae and Americae septentrionalis, (lectotype: LINN-87.41!, designated by Soreng 2000: 255). Description. Hermaphroditic. Perennials; extensively rhizomatous, shoots solitary, green or bluish-grey-green; tillers extravaginal (basally cataphyllous), with lateral and downward tending, cataphyllous shoots. Culms 15?0 cm tall, erect, bases usually geniculate, wiry, leafy, strongly compressed, smooth; nodes strongly compressed, 3? nodes usually exerted. Leaf sheaths distinctly compressed, minutely rough; butt sheaths papery, smooth, glabrous; flag leaf sheaths ca. 2? cm long, margins fused 10?0 the length, subequal to its blade; throats and collars smooth or slightly scabrous, glabrous; ligules 1? mm long, abaxially moderately to densely scabrous, upper margin ciliolate, apices obtuse; blades 1.5? mm wide, flat or folded, abaxially smooth, veins slightly expressed, margins scabrous, adaxially lightly scabrous over the veins, apices abruptly prow-tipped; cauline blades subequal; sterile shoot blades like those of the culm. Panicles 2?0 cm long, generally 1/6?/3 as broad as long, erect, contracted or slightly open, linear, lanceoloid to ovoid, often interrupted, sparse to congested, with 15 to 80 spikelets; rachis with mostly 1? branches per node; primary branches erect to ascending, or infrequently spreading, fairly strict, 2? angled, angles distinctly scabrous (at least in part); lateral pedicels 1/5?/3 their spikelet in length, scabrous, prickles moderately coarse; longest branches 0.5? cm, with 1?5 spikelets. Spikelets (2.3?3.5? mm long, laterally compressed; not bulbiferous; grayish, often anthocyanic tinged, not lustrous; florets 3?, hermaphroditic; rachilla internodes terete, mostly less than 1 mm long, smooth to muriculate; glumes lanceolate, subequal, distinctly keeled, keels scabrous; apices acute; lower glumes ca. 2 mm long, 3-veined; upper glumes ca. 2.1 mm long, 3-veined; calluses glabrous or more often webbed; web distinct, hairs short, woolly, sparse; lemmas 2.3?.5 mm long, lanceolate, distinctly keeled, keels and marginal veins short villous proximally, between veins smooth, glabrous, intermediate veins obscure, margins narrowly scarious-hyaline, edges smooth orRobert J. Soreng Paul M. Peterson / PhytoKeys 15: 1?04 (2012)with sparsely scaberulous, apices obtuse to acute; paleas densely scabrous over the keels, between keels smooth. Flowers chasmogamous; lodicules ca. 0.6 mm long, lanceolate, with a subequal lateral lobe in the upper 2/3; anthers 1.3?.8 mm long. Caryopses 1.4?.5 mm long, elliptical in side-view, subtrigonous to subcylindrical in cross-section, brown, shallowly sulcate, hilum 0.2 mm long, oval, grain adherent to the palea. 2n = 35, 42, 49, 50, 56. Distribution. This species is circumboreal in distribution and in North America it occurs in Canada, USA, and Mexico (Coahuila). Ecology. This strongly rhizomatous, ruderal species occurs in mesic, cool temperate, semi-shaded to open habitats in seasonally soggy soils, sands to clays, both derived from calcareous and igneous substrates. Once established, this specie.