Poa cusickii |
Poa abbreviata |
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Cusick's bluegrass |
abbreviated bluegrass, dwarf blue grass, northern blue grass, short 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; not or scarcely glaucous; densely tufted, not stoloniferous, not 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. |
5-15(20) cm, slender, leafless above the basal tuft. |
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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 1/10 – 1/4 their length, terete; ligules 0.4-5.5 mm, milky white to hyaline, smooth or scabrous, apices truncate to acute; blades 0.8-1.5(2) mm wide, involute, moderately thick, soft, apices narrowly prow-shaped. |
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Basal branching | intravaginal or intra- and extravaginal. |
all or mainly intravaginal. |
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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. |
1.5-5 cm, erect, lanceoloid to ovoid, contracted, congested; nodes with 1-3 branches; branches to 1.5 cm, erect, slender, terete, sulcate or angled, smooth or the angles sparsely scabrous; pedicels usually shorter than the 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. |
4-6.5 mm, laterally compressed, rarely bulbiferous, frequently strongly anthocyanic; florets 2-5, rarely bulb-forming; rachilla internodes usually shorter than 1 mm, smooth or scabrous. |
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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 to slightly longer than the adjacent lemmas, lanceolate to broadly lanceolate, distinctly keeled, keels smooth; lower glumes (1)3-veined, lateral veins often faint and short; upper glumes exceeding or exceeded by the upper florets; calluses glabrous or webbed; lemmas 3-4.6 mm, lanceolate to broadly lanceolate, distinctly keeled, thin, keels and marginal veins usually short- to long-villous, hairs extending along 3/4 - 5/6 of the keel, infrequently glabrous, intercostal regions glabrous or softly puberulent to short-villous, apices acute; palea keels scabrous, often short-villous to softly puberulent at midlength, sometimes glabrous; anthers 0.2-1.2(1.8) mm. |
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2n | = 28, 28+11, 56, 56+11, 59, ca. 70. |
= 42. |
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Poa cusickii |
Poa abbreviata |
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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; CA; CO; ID; MT; NV; OR; UT; WY; AB; BC; NT; NU; YT; Greenland |
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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 abbreviata is an alpine and circumarctic species which has two subspecies in the western Cordilleras, and one in the high arctic. It grows mainly on frost scars and mesic rocky slopes, usually on open ground. In rare cases where the lemmas and calluses of P. abbreviata ate glabrous, it can be confused with P. lettermanii (p. 580), but that species has shorter spikelets and glumes that are longer than the adjacent florets. (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 > subg. Poa > sect. Abbreviatae | ||||||||||||||||||||
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Name authority | Vasey | R. Br. | ||||||||||||||||||||
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