Poa lettermanii
Poa pseudoabbreviata
Letterman bluegrass, Letterman's blue grass
polar bluegrass, short-flower bluegrass, shortcoal bluegrass
1-12 cm, slender.
4-20(30) cm, to 18 cm in bulbiferous plants, slender.
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 1/10 – 1/6 their length, terete;
ligules 1-4 mm, smooth;
blades 0.5-1.5(2) mm wide, flat or folded, thin, soft, apices narrowly prow-shaped.
all or mainly intra-vaginal.
all or mainly intravaginal.
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.
2-7 cm, 2-4 cm in bulbiferous plants, widths equal to lengths, erect, broadly rhomboidal to pyramidal, open, exserted from the sheaths, sparse;
branches 1.5-5 cm, ascending to spreading, divaricate, slender, sulcate or angled, angles sparsely to moderately scabrous;
pedicels often longer than the spikelets.
3-4 mm, laterally compressed, green or anthocyanic;
florets 2-3;
rachilla internodes shorter than 1 mm, smooth.
3-5 mm, laterally compressed, rarely bulbiferous, usually strongly anthocyanic, glaucous or not;
florets 2-4, rarely bulb-forming;
rachilla internodes shorter than 1 mm, smooth to scabrous.
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.
distinctly keeled;
lower glumes subequal to equaling the lowest lemmas, 3-veined, upper glumes frequently longer than the lowest lemmas;
calluses glabrous;
lemmas 2-3 mm, lanceolate, distinctly keeled, thin, keels and marginal veins crisply puberulent, rarely glabrous, intercostal regions glabrous, apices acute;
paleas scabrous over the keels;
anthers 0.2-0.7 mm.
= 14.
= 14.
Poa lettermanii
Poa pseudoabbreviata
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 pseudoabbreviata is a low arctic to subarctic and alpine species of Alaska, northwestern Canada, Siberia, and the Russian Far East. It grows mainly on frost scars, rocky slopes, and ridges, often on open ground. It is one of only three diploid species native to the Western Hemisphere.
Poa pseudoabbreviata is easily distinguished from all other alpine and arctic species of Poa by its spreading, capillary branches, long pedicels, short stature, small spikelets, and glabrous calluses. Bulbiferous plants are known only from the Brooks Range, Alaska.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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