Poa lettermanii |
Poa unilateralis |
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Letterman bluegrass, Letterman's blue grass |
ocean bluff blue grass, San Francisco bluegrass, sea-bluff bluegrass |
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Habit | Plants perennial; not glaucous; densely tufted, not stoloniferous, not rhizomatous. | Plants perennial; frequently glaucous; densely tufted, not stoloniferous, not rhizomatous. | ||||
Culms | 1-12 cm, slender. |
5-40 cm, erect or ascending, frequently decumbent, terete, with 0-2 exserted nodes. |
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Sheaths | 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(1/5) their length, terete, smooth, glabrous, bases of basal sheaths glabrous, distal sheath lengths 1-4 times widths; ligules 2-6 mm, smooth or sparsely scabrous, obtuse to acute; innovation blades usually 1-1.5 mm wide, thin, soon withering, and distinctly narrower than the cauline blades, infrequently wider, flat, and a bit fleshy as in the cauline blades, or involute; cauline blades gradually reduced in length distally, 2-5 mm wide, flat or folded, soft, thin and soon withering or moderately thick and somewhat fleshy and retaining their form, smooth, apices narrowly to broadly prow-shaped. |
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Basal branching | all or mainly intra-vaginal. |
all or mainly intravaginal. |
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Panicles | 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. |
3-7 cm, erect, nearly cylindrical, contracted, congested, with (20)30-80(120) spikelets; nodes with 3-7 branches; branches 0.5-1.5(4.5) cm, erect, usually angled, infrequently terete or sulcate, angles usually moderately to densely scabrous, infrequently smooth with dense papillae and weak-angled, with 2-10 spikelets in the proximal 2/3; pedicels shorter than the spikelets. |
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Spikelets | 3-4 mm, laterally compressed, green or anthocyanic; florets 2-3; rachilla internodes shorter than 1 mm, smooth. |
4.5-7 mm, lengths to 3.5 times widths, lanceolate to narrowly ovate, drab; florets 3-5; rachilla internodes usually shorter than 1 mm, smooth. |
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Glumes | 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. |
lanceolate, slightly unequal, distinctly keeled, keels papillate or scabrous; lower glumes 3-veined; calluses glabrous or with a crown of hairs, hairs 0.1-0.2 mm; lemmas 3-4.5 mm, lanceolate, distinctly keeled, glabrous or the keels and marginal veins short-villous to midlength, intercostal regions sparsely puberulent near the base, margins glabrous, apices acute; palea keels scabrous, sometimes softly puberulent at midlength; anthers 1.5-3 mm. |
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2n | = 14. |
= 42, 84. |
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Poa lettermanii |
Poa unilateralis |
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Distribution |
CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC
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CA; OR; WA
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Discussion | 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 unilateralis grows on grassy bluffs and cliffs near the Pacific coast of North America, from Washington to California. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 24, p. 580. | FNA vol. 24, p. 594. | ||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Abbreviatae | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Secundae > subsect. Halophytae | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | P. mor.tevansi | |||||
Name authority | Vasey | Scribn. | ||||
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