Poa glauca |
Poa sect. Stenopoa |
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glaucous blue grass, timberline bluegrass, white bluegrass |
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Habit | Plants perennial; usually glaucous; densely tufted, not stoloniferous, not rhizomatous. | Plants perennial; densely to loosely tufted, not rhizomatous, infrequently stoloniferous. | ||||||||
Culms | 5-40(80) cm, erect to spreading, straight, wiry, bases straight or slightly decumbent; nodes terete or slightly compressed, usually 0-1 exserted, top node at 1/10-1/3 the culm length. |
5-120 cm, terete or slightly compressed; nodes terete or slightly compressed. |
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Sheaths | closed for 1/10 – 1/5 their length, terete, bases of basal sheaths glabrous or sparsely minutely hairy, hairs 0.1-0.2 mm, distal sheath lengths 1.1-4 times blade lengths; ligules 1-4(5) mm, sparsely to densely scabrous, apices obtuse to acute, minutely ciliolate; blades 0.8-2.5 mm wide, flat or folded, thin, soft, appressed or abruptly ascending to spreading, straight, apices narrowly prow-shaped. |
closed for 1/10 – 1/5 their length, terete or slightly compressed, smooth or sparsely scabrous, distal sheaths shorter or longer than their blades; ligules 0.2-6 mm, usually scabrous, sometimes smooth, apices truncate or obtuse and usually ciliolate, or acute and not ciliolate; blades 0.8-8 mm wide, mostly flat, sometimes folded, moderately thin, abruptly ascending to spreading, lax or straight, margins scabrous, adaxial surfaces usually scabrous over the veins, apices narrowly prow-shaped. |
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Basal branching | all or mostly extravaginal. |
all or mostly extravaginal. |
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Panicles | 1-10(20) cm, lengths 3-5 times widths at maturity, rarely racemelike with branches of irregular length, erect, narrowly lanceoloid to ovoid, contracted to somewhat open, sparse, proximal internodes shorter than 1.5(4) cm; nodes with 2-3(5) branches; branches erect, ascending or weakly spreading, fairly straight, short, stout, angled, angles moderately to densely scabrous, rarely only scabrous distally, glaucous; pedicels usually shorter than the spikelets. |
1-30(41) cm, erect or lax, open, narrowly lanceoloid to ovoid, sparse to moderately congested; nodes with 2-9 branches; branches 0.4-15 cm, erect to reflexed, angled, angles scabrous. |
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Spikelets | 3-7(9) mm, lengths 2-3 times widths, laterally compressed, rarely bulbiferous, usually glaucous; florets 2-5, rarely bulb-forming; rachilla internodes to 1.2 mm, smooth, muriculate, or scabrous, glabrous or sparsely to densely hispidulous or puberulent. |
3-8(9) mm, lengths 2-3.5 times widths, narrowly lanceolate to narrowly ovate, laterally compressed, rarely bulbiferous; florets (1)2-5, bisexual, rarely bulb-forming; rachilla internodes mostly shorter than 1 mm, frequently muriculate or scabrous or pubescent. |
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Glumes | subequal, narrowly to broadly lanceolate, distinctly keeled, keels smooth or sparsely scabrous, apices acute; lower glumes 3-veined; upper glumes 2-3.8(5.2) mm, lengths usually more than 4.1 times widths, distinctly shorter to subequal to the lowest lemmas; calluses glabrous or webbed, webs from minute to more than 1/2 the lemma length; lemmas 2.5-4 mm, lanceolate to broadly lanceolate, distinctly keeled, keels and marginal veins short-villous, lateral veins obscure, usually sparsely softly puberulent to short-villous, intercostal regions smooth, sometimes weakly muriculate, glabrous or puberulent, margins glabrous, apices usually partially bronze-colored, obtuse or acute; palea keels scabrous, glabrous or softly puberulent at midlength, intercostal regions glabrous or softly puberulent; anthers (1)1.2-2.5 mm, mature sacs 0.2 mm wide, rarely aborted late in development. |
subulate to broadly lanceolate, distinctly keeled, keels smooth or sparsely scabrous; lower glumes 3-veined; calluses terete or slightly laterally compressed, glabrous or dorsally webbed; lemmas 2-4 mm, narrowly to broadly lanceolate, distinctly keeled, coriaceous-membranous, usually finely muriculate, keels and marginal veins long- to short-villous, intercostal regions glabrous or softly puberulent to short-villous, lateral veins obscure, apices usually partially bronze-colored; palea keels scabrous, sometimes softly puberulent at midlength, intercostal regions glabrous or puberulent; anthers 3, 0.8-2.5 mm. |
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2n | = 34, 42, 44, 47, 48, 49, 50, 56, 56, 57, 58, 60, 63, 64, 65, 70, 75, 78, ca. 100. |
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Poa glauca |
Poa sect. Stenopoa |
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Distribution |
AK; AZ; CA; CO; ID; ME; MI; MN; MT; NH; NM; NV; NY; OR; PA; SD; UT; VT; WA; WI; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; QC; SK; YT; Greenland
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Discussion | Poa glauca is a common, highly variable, circumboreal, boreal forest to alpine and high arctic species. It grows from Alaska to Greenland, south to California and New Mexico in the west, and through Canada and the northeastern United States in the east. It also grows at scattered locations in Patagonia. It generally favors dry habitats and tolerates disturbance well. It can be distinguished from P. nemoralis (p. 574) and P. interior (see previous) by its longer ligules, lower top culm node, and wider glumes and lemmas. It can be difficult to distinguish from P. laxa subsp. banffiana (p. 570). Poa glauca is often confused in herbaria with P. abbreviata subsp. pattersonii (p. 582). It differs in having primarily extravaginal branching and, usually, longer anthers. It hybridizes with P. laxa, forming P. laxa x glauca (p. 572). It is also known to hybridize with P. hartzii (p. 589), and is suspected to hybridize with P. arctica (p. 529) and P. secunda (p. 586). It is highly polyploid, and presumed to be highly apomictic. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Poa sect. Stenopoa includes 30 species. Most are Eurasian; three are native in, and one is restricted to, the Flora region. The North American species are cespitose or weakly stoloniferous, and have sheaths open for much of their length, scabrous panicle branches, and faint lateral lemma veins. The new shoots for the following year are initiated late in the growing season, after flowering and fruiting; vegetative and flowering shoots are usually not present at the same time. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 24, p. 576. | FNA vol. 24. | ||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Stenopoa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa | ||||||||
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Name authority | Vahl | Dumort. | ||||||||
Web links |