Poa cusickii |
Poa douglasii |
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Cusick's bluegrass |
Douglas' bluegrass, sand dune blue grass |
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Habit | Plants perennial; usually densely tufted, rarely moderately densely tufted, usually neither rhizomatous nor stoloniferous, infrequently short-rhizomatous or stoloniferous, rarely with distinct rhizomes. | Plants perennial; loosely tufted, rhizomatous and stoloniferous, rhizomes and stolons to 1 m. | ||||||||||||
Culms | 10-60(70) cm tall, 0.5-1.8 mm thick, erect or the bases decumbent, terete or weakly compressed; nodes terete, 0-2 exserted. |
(5)10-30 cm tall, 1.2-1.5 mm thick, bases decumbent, terete or weakly compressed, hispidulous beneath the panicles; nodes terete, 0(1) exserted. |
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Sheaths | closed for 1/4-3/4 their length, terete, smooth or scabrous, glabrous, bases of basal sheaths glabrous, distal sheath lengths 1.6-10 times blade lengths; collars smooth or scabrous, glabrous; ligules of cauline leaves 1-3(6) mm, smooth or scabrous, truncate to acute, ligules of the innovation leaves 0.2-0.5(2.5) mm, scabrous, usually truncate; innovation blades sometimes distinctly different from the cauline blades, 0.5-2 mm wide, involute, moderately thick, moderately firm, adaxial surfaces usually densely scabrous or hispidulous to softly puberulent, infrequently nearly smooth and glabrous; cauline blades subequal or the midcauline blades longest or the blades gradually reduced in length distally, 0.5-3 mm wide, flat, folded, or involute, usually thin, usually withering, abaxial surfaces smooth or scabrous, apices narrowly to broadly prow-shaped, flag leaf blades 0.5-5(6) cm. |
closed for about 1/2 their length, terete, smooth or sparsely to moderately retrorsely scabrous near the collars, glabrous, bases of basal sheaths glabrous, distal sheath lengths 0.9-3.5 times blade lengths; collars sparsely to moderately retrorsely scabrous, glabrous; ligules 1-2 mm, scabrous, truncate to obtuse, ciliolate; innovation blades to 30 cm long, adaxial surfaces moderately to densely scabrous or hispidulous on and between the veins; cauline blades subequal in length, 1-2 mm wide, involute, moderately thick, moderately firm, arcuate, abaxial surfaces smooth or sparsely scabrous, adaxial surfaces moderately to densely scabrous or hispidulous on and between the veins, apices narrowly prow-shaped, flag leaf blades 1-9 cm. |
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Basal branching | intravaginal or intra- and extravaginal. |
mainly intravaginal, some extravaginal. |
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Panicles | 2-10(12) cm, usually erect, contracted or loosely contracted, narrowly lanceoloid to ovoid, congested or moderately congested, with 10-100 spikelets and 1-3(5) branches per node; branches 0.5-4(5) cm, erect or steeply ascending, fairly straight, slender to stout, terete to angled, smooth or scabrous, with 1-15 spikelets. |
1.5-6 cm, erect, compact, ovoid, contracted, infrequently interrupted, congested, with 15-50 spikelets; nodes with 1-2 branches, internodes densely hispidulous; branches 0.5-2 cm, erect, stiff, terete to weakly angled, densely hispidulous, with 1-5 spikelets. |
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Spikelets | (3)4-10 mm, lengths to 3 times widths, broadly lanceolate to narrowly ovate, laterally compressed, not sexually dimorphic; florets 2-6; rachilla internodes 0.5-1.2 mm, smooth or scabrous. |
7-12 mm, lengths to 3 times widths, laterally compressed, not sexually dimorphic; florets 3-6; rachilla internodes usually shorter than 0.5 mm, smooth, glabrous. |
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Glumes | lanceolate, distinctly keeled; lower glumes 3-veined, distinctly shorter than the lowest lemmas; calluses glabrous or diffusely webbed, hairs less than 1/4 the lemma length; lemmas (3)4-7 mm, lanceolate to broadly lanceolate, distinctly keeled, membranous to thinly membranous, smooth or sparsely to densely scabrous, glabrous or the keels and/or marginal veins puberulent proximally, lateral veins obscure to prominent, margins glabrous, apices acute; palea keels scabrous, intercostal regions glabrous; anthers vestigial (0.1-0.2 mm), aborted late in development, or 2-3.5 mm. |
broadly lanceolate, 1/2 as long as to subequal to the adjacent lemmas, distinctly keeled; lower glumes 3-veined; upper glumes 4-4.5(7+) mm, 3-veined; calluses usually with a crown of hairs, sometimes glabrous or diffusely webbed; lemmas 5-7.5 mm, lanceolate, 5-veined, distinctly keeled, keels, marginal veins, and sometimes the lateral veins short- to long-villous or softly puberulent, rarely glabrous, lateral veins moderately prominent, intercostal regions smooth, glabrous, margins glabrous, apices acute; palea keels scabrous to pectinate-ciliate, intercostal regions glabrous; anthers vestigial (0.1-0.2 mm) or (2)2.5-3.5 (4) mm. |
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2n | = 28, 28+11, 56, 56+11, 59, ca. 70. |
= 28. |
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Poa cusickii |
Poa douglasii |
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Distribution |
CA; CO; ID; MT; ND; NV; OR; UT; WA; WY; AB; BC; MB; SK; YT
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CA
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Discussion | Poa cusickii grows in rich meadows in sagebrush scrub to rocky alpine slopes, from the southwestern Yukon Territory to Manitoba and North Dakota, south to central California and eastern Colorado. It is gynodioecious or dioecious. Sexually reproducing plants of Poa cusickii subspp. cusickii and pallida grow in different geographic areas, but pistillate plants of these two subspecies have overlapping ranges. Only pistillate plants are known in Poa cusickii subspp. epilis and purpurascens. All the alpine plants studied were pistillate. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Poa douglasii is a dioecious endemic that grows on coastal sand dunes in California, a habitat that is being invaded by exotic species. It is rare north of Mendocino. Its hairy rachises distinguish P. douglasii from all other species of Poa in the Flora region. It differs from P. macrantha (see next), which occupies similar habitats, in this and in its usually longer glumes and lemmas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 24, p. 559. | FNA vol. 24, p. 551. | ||||||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Epiles | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Madropoa | ||||||||||||
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Name authority | Vasey | Nees | ||||||||||||
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