Poa cusickii |
Poa ×gaspensis |
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Cusick's bluegrass |
Gaspé Peninsula 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; densely to loosely tufted, rhizomatous. | ||||||||||||
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. |
15-50 cm, erect or the bases decumbent. |
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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 1/4-1/2 their length, terete; ligules acute; blades flat, thin, apices broadly prow-shaped. |
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Basal branching | intravaginal or intra- and extravaginal. |
intra- and 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. |
erect, narrowly lanceoloid to ovoid, contracted, with 2-4 branches per node; branches ascending to spreading, sparsely scabrous. |
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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. |
3.5-6 mm, laterally compressed, with 3-4 florets. |
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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, distinctly keeled, distinctly scabrous on the distal 1/3; lower glumes 3-veined; calluses shortly webbed; lemmas 2.5-4.5 mm, broadly lanceolate, keeled, keels and marginal veins long-villous, intercostal regions sofdy puberulent; palea keels scabrous, long-villous at midlength; anthers 1.2-1.4 mm. |
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2n | = 28, 28+11, 56, 56+11, 59, ca. 70. |
= unknown. |
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Poa cusickii |
Poa ×gaspensis |
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Distribution |
CA; CO; ID; MT; ND; NV; OR; UT; WA; WY; AB; BC; MB; SK; YT
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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 ×gaspensis is found in the coastal mountains of the Gaspe Pennisula. There are few plants that fit the description. It seems to consist of hybrids between P. pratensis subsp. alpigena (p. 525) and P. alpina (p. 518). Poa xgaspensis differs from P. alpina in its extravaginal branching, rhizomatous habit, and webbed calluses; from P. pratensis in its acute ligules and more pubescent lemmas; and from P. arctica (p. 529) in its sharply keeled, more scabrous glumes and its spikelet shape, which approaches those of P. alpina and P. pratensis. Poa ×gaspensis is a named intersectional hybrid (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. | ||||||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Epiles | Poaceae > subfam. Pooideae > tribe Poeae > Poa | ||||||||||||
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Subordinate taxa | ||||||||||||||
Name authority | Vasey | Fernald | ||||||||||||
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