Poa stenantha |
Poa alpina |
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narrow-flower bluegrass, northern bluegrass |
alpine blue grass |
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Habit | Plants perennial; glaucous or not; densely to loosely tufted, not stoloniferous, not rhizomatous. | Plants perennial; not glaucous; densely cespitose, not rhizomatous, not stoloniferous. | ||||||||
Culms | 20-60(100) cm, bases decumbent or sometimes erect, terete, with 1-2 exserted nodes. |
10-40 cm. |
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Sheaths | closed for 1/10 – 1/5(1/4) their length, terete, bases of basal sheaths glabrous; ligules 2-5 mm, milky white, smooth or sparsely scabrous, acute to acuminate; innovation blades similar in texture and shape to the cauline blades; cauline blades not greatly reduced upwards, 1.5-4(5) mm wide, flat or folded, thin, lax, smooth or sparsely scabrous, apices narrowly prow-shaped. |
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Basal branching | mostly extravaginal, some 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 | 5-18(25) cm, lax, loosely contracted to open, sparse, with 20-65 spikelets and usually 2(7) branches per node; branches 3-15 cm, ascending to spreading, angled, angles finely to coarsely, sparsely to fairly densely scabrous, infrequently smooth, with 3-10(15) spikelets in the distal 1/2. |
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. |
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Spikelets | 6-10 mm, lengths 3-3.6 times widths, lanceolate to narrowly ovate, laterally compressed, sometimes bulbiferous, drab, often slightly glaucous; florets 3-4(7), normal or bulb-forming; rachilla internodes 1.2-2 mm, slightly dorsally compressed, smooth or sparsely muriculate. |
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. |
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Glumes | subequal, lanceolate to broadly lanceolate, dull, frequently glaucous, obtuse to acute; lower glumes 3-veined; upper glumes (3.7)4.1-6.5 mm; calluses usually crowned with 0.2-2 mm hairs, sometimes glabrous; lemmas 4-6 mm, lanceolate, distinctly compressed, distinctly keeled, keels, marginal veins, and sometimes the lateral veins short- to long-villous, hairs extending for 3/4 of the keel, intercostal regions glabrous, sparsely puberulent or hispidulous proximally, usually sparsely to moderately densely scabrous distally, hairs distinctly shorter than those of the keel and veins, margins weakly inrolled, broadly scarious, glabrous, apices acute; palea keels scabrous, often softly puberulent at midlength, intercostal regions glabrous or puberulent; anthers 1.2-2 mm, sometimes aborted late in development or undeveloped. |
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. |
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2n | = 42, [81, 84, 86?]. |
= 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. |
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Poa stenantha |
Poa alpina |
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Distribution |
AK; CO; ID; MT; OR; UT; WA; AB; BC
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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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Discussion | Poa stenantha grows in coastal meadows and on cliffs in subarctic and boreal forests; it is less common in moist, more southern subalpine and low alpine meadows and thickets. Its range extends from western Alaska to the northern Cascades and Rocky Mountains and, as a disjunct, to Patagonia. Poa stenantha was originally described as growing in Kamchatka, Russia, but the Russian plants have since been referred to other species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
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Key |
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Source | FNA vol. 24, p. 592. | FNA vol. 24. | ||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Secundae > subsect. Halophytae | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Alpinae | ||||||||
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Synonyms | P. macroclada | |||||||||
Name authority | Trin. | L. | ||||||||
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