Poa glauca |
Poa ×gaspensis |
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glaucous blue grass, timberline bluegrass, white bluegrass |
Gaspé Peninsula bluegrass |
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Habit | Plants perennial; usually glaucous; densely tufted, not stoloniferous, not rhizomatous. | Plants perennial; densely to loosely tufted, rhizomatous. | ||||||||
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. |
15-50 cm, erect or the bases decumbent. |
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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 1/4-1/2 their length, terete; ligules acute; blades flat, thin, apices broadly prow-shaped. |
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Basal branching | all or mostly extravaginal. |
intra- and 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. |
erect, narrowly lanceoloid to ovoid, contracted, with 2-4 branches per node; branches ascending to spreading, sparsely 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. |
3.5-6 mm, laterally compressed, with 3-4 florets. |
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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. |
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 | = 34, 42, 44, 47, 48, 49, 50, 56, 56, 57, 58, 60, 63, 64, 65, 70, 75, 78, ca. 100. |
= unknown. |
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Poa glauca |
Poa ×gaspensis |
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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 ×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. 576. | FNA vol. 24. | ||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Stenopoa | Poaceae > subfam. Pooideae > tribe Poeae > Poa | ||||||||
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Name authority | Vahl | Fernald | ||||||||
Web links |