Poa leptocoma |
Poa cusickii |
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bog bluegrass, marsh blue grass, western bog bluegrass |
Cusick's bluegrass |
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Habit | Plants perennial; dark to light green, often anthocyanic in part; loosely tufted, usually neither stoloniferous nor rhizomatous, occasionally with short, slender rhizomes. | Plants perennial; usually densely tufted, rarely moderately densely tufted, usually neither rhizomatous nor stoloniferous, infrequently short-rhizomatous or stoloniferous, rarely with distinct rhizomes. | ||||||||||||
Culms | 15-100 cm, slender to middling. |
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. |
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Sheaths | closed for 1/4 - 3/5 their length, terete, smooth or sparsely scabrous, margins not ciliate; ligules 1.5-4(6) mm, smooth to sparsely scabrous, obtuse to acute; blades 1-4 mm wide, flat, thin, lax, soft, apices narrowly prow-shaped. |
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. |
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Basal branching | mostly extravaginal. |
intravaginal or intra- and extravaginal. |
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Panicles | 5-15 cm, lax, open, sparse; nodes with 1-3(5) branches; branches (2)3-8 cm, spreading to reflexed, capillary, usually angled, infrequently only sulcate or subterete, angles usually moderately densely scabrous, sometimes only sparsely so, with (3)4-15 spikelets. |
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. |
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Spikelets | 4-8 mm, lanceolate or narrowly lanceolate, green or partly purple to dark purple; florets 2-5; rachilla internodes smooth, glabrous. |
(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. |
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Glumes | subulate to lanceolate, thin, distinctly keeled, keels usually scabrous; lower glumes subulate to narrowly lanceolate, 1-veined; upper glumes distinctly shorter than to nearly equaling the lowest lemmas; calluses sparsely webbed; lemmas 3-4 mm, lanceolate, often partly purple, distinctly keeled, thin, smooth, or with sparse hooks apically, keels and marginal veins softly puberulent to long-villous, hairs extending 1/4 - 2/3 the keel length, sometimes sparse, lateral veins and intercostal regions glabrous, margins glabrous, infolded, apices sharply acute to acuminate, usually bronze-colored; palea keels nearly smooth, scabrous, or pectinately ciliate; anthers 0.2-1.1 mm. |
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. |
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2n | = 42. |
= 28, 28+11, 56, 56+11, 59, ca. 70. |
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Poa leptocoma |
Poa cusickii |
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Distribution |
AK; AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC; YT
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CA; CO; ID; MT; ND; NV; OR; UT; WA; WY; AB; BC; MB; SK; YT
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Discussion | Poa leptocoma grows around lakes and ponds and along streams, in subalpine and alpine to low arctic habitats, in western North America from Alaska to California and New Mexico, and on the Kamchatka Peninsula, Russia. It often grows with or near P. reflexa (p. 538), from which it differs in its more scabrous panicle branches, shorter anthers, glabrous or pectinately ciliate palea keels, and preference for wet sites. The two also differ in their ploidy level, P. leptocoma being hexaploid, and P. reflexa tetraploid. It differs from P. paucispicula (p. 538) in its more scabrous panicle branches, narrower glumes and lemmas, and its more sparsely hairy calluses and lemmas. Although its chloroplast haplotype is similar to that of species in sect. Oreinos, its ITS sequence is distinct and resembles that of P. paucispicula. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
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Key |
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Source | FNA vol. 24, p. 573. | FNA vol. 24, p. 559. | ||||||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Oreinos | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Epiles | ||||||||||||
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Name authority | Trin. | Vasey | ||||||||||||
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