Poa alpina |
Poa bulbosa |
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alpine blue grass |
bulbous blue grass |
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Habit | Plants perennial; not glaucous; densely cespitose, not rhizomatous, not stoloniferous. | Plants perennial; densely tufted, not rhizomatous, not stoloniferous. | ||||||||
Culms | 10-40 cm. |
15-60 cm, erect or spreading, bases bulbous. |
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Sheaths | closed for about 1/4 their length, terete, lowest sheaths with swollen bases; ligules 1-3 mm, smooth or scabrous, apices obtuse to acute; blades 1-2.5 mm wide, flat, thin, lax, soon withering. |
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Basal branching | intravaginal. |
intravaginal. |
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Leaves | mostly basal; sheaths closed for 1/8 – 2/7 their length, terete, basal sheaths persistent, overlapping, bases usually not swollen; ligules of innovations 1-2(3) mm, those of the upper cauline leaves to 4(5) mm, milky white, smooth, glabrous, obtuse; blades of innovations widely spreading, persisting through the season, blades of cauline leaves 1-5(12) cm long, 2-4.5 mm wide, flat, moderately thick, soft, straight, smooth or the margins sparsely scabrous, apices broadly prow-shaped, blades of upper cauline leaves much reduced in length. |
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Panicles | 2-6(8) cm, erect, ovoid to pyramidal, open or loosely contracted at maturity, fairly congested; nodes with 1-2 branches, lowest internodes 0.6-1(1.5) cm; branches 1-3(4) cm, ascending to spreading, straight, terete, usually smooth or sparsely scabrous, rarely moderately densely scabrous; pedicels divaricate, shorter than the spikelets. |
3-12 cm, ovoid; nodes with 2-5 branches; branches ascending to spreading, terete, usually smooth or sparsely scabrous, infrequently moderately scabrous. |
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Spikelets | 3.9-6.2 mm, ovate, lengths 1.5-2.5 times widths, laterally compressed, plump, sometimes bulbiferous; florets 3-7, usually normal; rachilla internodes 0.5-0.8 mm, smooth, glabrous or sparsely softly puberulent to short-villous. |
3-5 mm, laterally compressed, usually bulbiferous; florets 3-7, the basal floret, and sometimes additional florets, normal; rachilla internodes smooth, glabrous. |
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Glumes | broadly lanceolate to narrowly ovate, keeled, keels sparsely scabrous; lower glumes 3-veined; upper glumes shorter than or subequal to the lowest lemmas; calluses glabrous; lemmas 3-5 mm, broadly lanceolate, keeled, keels and marginal veins short- to long-villous, lateral veins moderately prominent, intercostal regions sparsely to moderately short-villous, apices acute; palea keels softly puberulent to short-villous over most of their length, apices scabrous; anthers 1.3-2.3 mm. |
keeled, keels scabrous; lower glumes 3-veined; upper glumes shorter than or subequal to the lowest lemmas; calluses webbed or glabrous; lemmas 3-4 mm, lanceolate, keeled, glabrous or the keels and marginal veins short- to long-villous, intercostal regions glabrous or softly puberulent, apices acute; paleas scabrous, keels often softly puberulent at midlength; anthers 1.2-1.5 mm and functional, sometimes aborted late in development, sometimes not developed. |
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2n | = 22, 23, 24,25, 26, 27, 28, 28+11, 30, 31, 32, 32+1, 33, 34, 35, 36, 37, 39, 40+1, 41, 42, ca. 43, 44, 46, ca. 48, 56. |
= 14, 21, 28, 39, 42, 45. |
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Poa alpina |
Poa bulbosa |
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Distribution |
AK; CO; ID; MI; MT; NM; NV; OR; UT; WA; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; QC; SK; YT; Greenland
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AR; AZ; CA; CO; CT; DE; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; MI; MN; MO; MT; NC; ND; NE; NJ; NM; NV; NY; OH; OK; OR; PA; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY
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Discussion | Poa alpina is a fairly common circumboreal forest species of subalpine to arctic habitats, extending south in the Rocky Mountains to Utah and Colorado in the west, and to the northern Great Lakes region in the east. It often grows in disturbed ground and is calciphilic. Poa xgaspensis (p. 601) is a natural hybrid which seems to be between P. alpina and P. pratensis subsp. alpigena (p. 525); it differs from P. alpina in its extravaginal branching, rhizomatous habit, and webbed calluses. The range of chromosome numbers suggests that P. alpina is predominantly apomictic. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Poa bulbosa is a European species that is now established in the Flora region. In southern Europe and the Middle East, it is considered an important early spring forage. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 24. | FNA vol. 24, p. 516. | ||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Alpinae | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Arenariae | ||||||||
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Name authority | L. | L. | ||||||||
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