Poa lettermanii
Poa paludigena
Letterman bluegrass, Letterman's blue grass
bog bluegrass, eastern bog bluegrass
1-12 cm, slender.
10-55 cm, very slender, weak.
closed for 1/6 – 1/4 their length, terete;
ligules 1-3 mm, milky white to hyaline, smooth;
blades 0.5-2 mm wide, flat or folded, or slightly inrolled, thin, without papillae (at 100x), apices narrowly prow-shaped.
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.
all or mainly intra-vaginal.
mostly extravaginal.
1-3 cm, erect, contracted, usually exserted from the sheaths;
branches to 1.5 cm, erect to steeply ascending, slender, sulcate or angled, smooth or the angles sparsely scabrous;
pedicels shorter than the spikelets.
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.
3-4 mm, laterally compressed, green or anthocyanic;
florets 2-3;
rachilla internodes shorter than 1 mm, smooth.
3.2-5.2 mm, laterally compressed, broadly lanceolate to ovate;
florets 2-3(5);
rachilla internodes smooth, glabrous.
usually equaling or exceeding the lowest lemmas, sometimes also equaling or exceeding the upper florets, lanceolate to broadly lanceolate, distinctly keeled, keels smooth;
lower glumes 3-veined;
calluses glabrous;
lemmas 2.5-3 mm, lanceolate, distinctly keeled, thin, usually glabrous, keels and marginal veins rarely sparsely puberulent proximally, apices acute;
palea keels scabrous;
anthers 0.2-0.8 mm.
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.
= 14.
= unknown.
Poa lettermanii
Poa paludigena
Poa lettermanii grows on rocky slopes of the highest peaks and ridges in the alpine zone, from northern British Columbia to western Alberta and south to California and Colorado, usually in the shelter of rocks or on mesic to wet, frost-scarred slopes. It is one of only three known diploid Poa species native to the Western Hemisphere. Its glabrous calluses and lemmas usually distinguish it from P. abbreviata (p. 582); it also differs in having flat or folded leaf blades, and shorter spikelets with glumes that are longer than the adjacent florets. Poa montevansii E.H. Kelso is tentatively included here, although its slightly longer lemmas that slightly exceed the glumes suggest that it may represent rare, glabrous forms of P. abbreviata.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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