Poa paludigena
Poa compressa
bog bluegrass, eastern bog bluegrass
Canada blue grass, Canadian blue grass, flat-stem blue grass
10-55 cm, very slender, weak.
15-60 cm, wiry, bases usually geniculate, strongly compressed;
nodes strongly compressed, some proximal nodes usually exserted.
closed for 1/4 - 3/5 their length, terete, smooth or sparsely scabrous, margins not ciliate;
ligules 0.5-2 mm, smooth or sparsely scabrous, truncate;
blades 0.8-2 mm wide, flat, thin, soft, apices narrowly prow-shaped.
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.
mostly extravaginal.
3-8(12) cm, lax, open, sparse;
nodes with 1-2(3) branches;
branches (2)3-7 cm, spreading to reflexed, capillary, angled, angles 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.
3.2-5.2 mm, laterally compressed, broadly lanceolate to ovate;
florets 2-3(5);
rachilla internodes smooth, glabrous.
(2.3)3.5-7 mm, laterally compressed;
florets 3-7;
rachilla internodes usually shorter than 1 mm, smooth to muriculate.
narrowly lanceolate to lanceolate, thin, distinctly keeled, keels scabrous;
lower glumes 1-3-veined;
upper glumes shorter than or subequal to the adjacent lemmas;
calluses sparsely webbed;
lemmas 2.5-4 mm, lanceolate, green, distinctly keeled, keels and marginal veins short-villous, extending 2/3 – 4/5 the keel length, lateral veins fairly prominent, intercostal regions glabrous, apices obtuse to broadly acute, white, faintly bronze-colored or not;
palea keels scabrous;
anthers 0.2-0.8 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.
= unknown.
= 35, 42, 49, 50, 56, 84.
Poa paludigena
Poa compressa
Poa paludigena is an inconspicuous species restricted to the northeastern United States. It grows in shady bogs and fens, often underneath other plants. Poa trivialis (p. 568) sometimes grows with P. paludigena; the former has distinctly longer ligules and anthers. Plants from the middle Appalachian Mountains are sometimes confused with P. sylvestris (p. 512). Poa paludigena is generally shorter and more slender, has shorter panicles with only 1-2 branches per node, is glabrous between the lemma veins and on the palea keels, has shorter anthers, and grows in colder habitats.
(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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