Poa wolfii
Poa compressa
Wolf's bluegrass
Canada blue grass, Canadian blue grass, flat-stem blue grass
25-90 cm.
15-60 cm, wiry, bases usually geniculate, strongly compressed;
nodes strongly compressed, some proximal nodes usually exserted.
closed for 1/2 - 3/4 their length, smooth or sparsely scabrous, margins not ciliate;
ligules 0.3-2.1 mm, smooth or sparsely scabrous, truncate to obtuse, ciliolate;
blades 0.6-3.5 mm wide, flat.
closed for 1/10 – 1/5 their length, distinctly compressed, bases of basal sheaths glabrous;
ligules 1-3 mm, moderately to densely scabrous, ciliolate, apices obtuse;
blades 1.5-4 mm wide, flat, cauline blades subequal.
mainly pseudointravaginal.
7.5-15(18) cm, lax, pyramidal, open, sparse;
nodes with 1-3(5) branches;
branches 3-8 cm, ascending, straight to spreading, angled, angles prominent, scabrous.
2-10 cm, generally 1/6 - 1/3 as wide as long, erect, linear, lanceoloid to ovoid, often interrupted, sparse to congested, with 15-80 spikelets and mostly with 1-3 branches per node;
branches 0.5-3 cm, erect to ascending, or infrequently spreading, angles densely scabrous, at least in part, with 1-15 spikelets.
4-6.5 mm, laterally compressed;
florets 2-5;
rachilla internodes to 1 mm, smooth, glabrous.
(2.3)3.5-7 mm, laterally compressed;
florets 3-7;
rachilla internodes usually shorter than 1 mm, smooth to muriculate.
1/2-1/3 the length of the adjacent lemmas, distinctly keeled, keels scabrous;
lower glumes subulate to narrowly lanceolate, (1)3-veined;
upper glumes shorter than or subequal to the lowest lemmas;
calluses webbed;
lemmas (2.5)3.2-4.7 mm, lanceolate, green, distinctly keeled, keels and marginal veins long-villous, hairs extending up almost the whole keel length, lateral veins prominent, intercostal regions smooth, minutely bumpy, usually glabrous, rarely sparsely softly puberulent, apices acute, blunt, or pointed, white, not bronze;
palea keels softly puberulent at midlength, apices scabrous;
anthers (0.5)0.8-1.2(1.5) mm.
distinctly keeled;
lower glumes 3-veined;
calluses usually webbed, sometimes glabrous;
lemmas 2.3-3.5 mm, lanceolate, distinctly keeled, keels and marginal veins short-villous, intercostal regions glabrous, lateral veins obscure, margins glabrous, apices acute;
paleas scabrous over the keels;
anthers 1.3-1.8 mm.
= 28.
= 35, 42, 49, 50, 56, 84.
Poa wolfii
Poa compressa
Poa wolfii is an uncommon species that grows in boggy areas of eastern deciduous forests, primarily west of the Appalachian divide. It differs from P. sylvestris (p. 512) in having fewer branches, larger spikelets, and lemmas that are usually glabrous between the veins.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Poa compressa is common in much of the Flora region. It is sometimes considered to be native, but this seems doubtful. It is rare and thought to be introduced in Siberia and only local in the Russian Far East, but is common in Europe. In the Flora region, it is often seeded for soil stabilization, and has frequently escaped. It grows mainly in riparian areas, wet meadows, and disturbed ground. Its distinctly compressed nodes and culms, exserted lower culm nodes, rhizomatous growth habit, and scabrous panicle branches make it easily identifiable.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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