Poa cusickii |
Poa macrocalyx |
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Cusick's bluegrass |
large-glume bluegrass |
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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; green or strongly purplish; rhizomatous, rhizomes sometimes poorly developed, densely to loosely tufted. | ||||||||||||
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. |
(20)30-120 cm, usually stout, erect or decumbent, not branching above the base, terete or weakly compressed; nodes terete, 1-2 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 1/4 - 3/5 their length, terete to compressed, usually distinctly keeled, glabrous, sparsely to moderately scabrous, bases of basal sheaths glabrous, distal sheath lengths (0.8)1-2(2.5) times blade lengths; collars smooth, glabrous; ligules 2-5(6) mm, usually smooth, ligules of proximal leaves sometimes scabrous, obtuse, those of the distal leaves acute; blades 4-12(18) cm long, (2)3-7 mm wide, flat or loosely folded, glabrous, both surfaces smooth or the adaxial surfaces sparsely scabrous, apices broadly prow-shaped, cauline blades subequal, flag leaf blades 3-10 cm. |
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Basal branching | intravaginal or intra- and extravaginal. |
all or mainly 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. |
(4)7-15(20) cm, lax, loosely contracted or open, moderately congested, with (15)20-100 spikelets and 2-4(5) branches per node; branches 3-8 cm, ascending or eventually spreading, flexuous, terete or weakly angled, usually sparsely scabridulous or scabrous, infrequently moderately densely scabrous, with (3)5-15(30) spikelets moderately crowded in the distal 1/2. |
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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. |
(5)6-9(12) mm, lengths to 3 times widths, laterally compressed, sometimes bulbiferous; florets 2-5, infrequently bulb-forming; rachilla internodes smooth or sparsely hispidulous. |
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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. |
subequal in length and width, usually nearly equaling the adjacent lemmas, lanceolate to broadly lanceolate, distinctly keeled, keels sparsely to moderately scabrous distally, lateral veins prominent; lower glumes (4)4.5-7 mm, 3-veined: upper glumes (4)4.5-7(8) mm, 3(5)-veined; calluses dorsally webbed, hairs 1/3 – 2/3 times the lemma length, copious; lemmas (4)5-8 mm, lanceolate to broadly lanceolate, green or purple, distinctly keeled, keels and marginal veins long-villous, lateral veins prominent, usually softly puberulent to short-villous, intercostal regions sometimes hispidulous, infrequently softly puberulent or short-villous proximally and hispidulous in the central 1/3, sometimes merely muriculate proximally and scabrous distally, sometimes densely scabrous throughout, rarely glabrous and nearly smooth proximally and sparsely scabrous distally, margins broadly hyaline, glabrous, apices acute; palea keels scabrous, sometimes softly puberulent at midlength, intercostal regions broad, distinctly hispidulous or softly puberulent; anthers 1.5-2.5 mm. |
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2n | = 28, 28+11, 56, 56+11, 59, ca. 70. |
= 42, 43, 44, 45, ca. 46, 49, 56, ca. 58, 63, ca. 64, ca. 65, 66, 67, 68, 69, 70, ca. 71, ca. 72, ca. 73, 74, 75, 76, 77, 78, 80, ca. 82, ca. 84, ca. 87, ca. 100. |
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Poa cusickii |
Poa macrocalyx |
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Distribution |
CA; CO; ID; MT; ND; NV; OR; UT; WA; WY; AB; BC; MB; SK; YT
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AK; BC |
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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 macrocalyx grows mainly in coastal areas of boreal Alaska, and from the eastern coast of Russia to northern Japan. Bulbiferous plants are occasionally found. Poa macrocalyx resembles an exaggeratedly robust P. pratensis (p. 522), with large spikelets and lemmas, proportionally longer glumes, and paleas that are generally hispidulous between the veins and palea keels. It is cytologically and morphologically complex, and is sometimes difficult to distinguish from P. arctica subsp. lanata (see below). Poa norbergii Hulten may belong to this species; alternatively, it may be a hybrid between P. glauca (p. 576) and P. arctica (p. 576) or P. macrocalyx. (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. 527. | ||||||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Epiles | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Poa | ||||||||||||
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Subordinate taxa | ||||||||||||||
Synonyms | P. turneri, P. ×norbergii, P. hispidula | |||||||||||||
Name authority | Vasey | Trautv. & CA. Mey. | ||||||||||||
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