Poa glauca |
Poa autumnalis |
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glaucous blue grass, timberline bluegrass, white bluegrass |
autumn bluegrass |
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Habit | Plants perennial; usually glaucous; densely tufted, not stoloniferous, not rhizomatous. | Plants perennial; not rhizomatous, not stoloniferous, loosely tufted. | ||||||||
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. |
23-86 cm tall, 0.8-1.8 mm thick, bases often 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 1/3 – 1/2 their length; ligules 0.2-1.9(2.5) mm, smooth or obtuse; blades (0.5)1-4 mm wide, flat or folded, thin. |
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Basal branching | all or mostly extravaginal. |
mainly pseudointravaginal. |
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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. |
(5)8-20 cm, erect or lax, broadly pyramidal at maturity, open, sparse, lower axils sometimes sparsely pubescent; nodes with 1-2(4) branches; branches 5-12 cm, spreading to reflexed, straight, angled, angles scabrous, with 3-8 spikelets in the distal 1/4-1/3. |
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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. |
3-8.2 mm, laterally compressed; florets 2-4(6); rachilla internodes smooth, sparsely softly puberulent. |
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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. |
distinctly shorter than the adjacent lemmas, distinctly keeled, keels scabrous; lower glumes subulate to lanceolate, (1)3-veined; upper glumes lanceolate to broadly lanceolate; calluses usually glabrous, rarely sparsely and shortly webbed; lemmas (2.8)3-4.6 mm, lanceolate, distinctly keeled, keels and marginal veins short- to long-villous, hairs extending up 3/4 of the keel, lateral veins prominent, intercostal regions softly puberulent, smooth, apices obtuse, blunt; palea keels softly puberulent to short-villous for much of their length, apices scabrous; anthers 1-1.4(2.6) 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. |
= 28. |
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Poa glauca |
Poa autumnalis |
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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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AL; AR; DC; DE; FL; GA; IL; IN; KY; LA; MD; MI; MS; NC; NJ; OK; PA; SC; TN; TX; VA; NU; QC; 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 autumnalis grows primarily in the southeastern United States, being found in forests of the eastern and western Appalachian piedmont and coastal plain. It is readily distinguished from other perennial species of the eastern United States by its combination of glabrous calluses and pubescent palea keels. (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, p. 514. | ||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Stenopoa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Sylvestres | ||||||||
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Subordinate taxa | ||||||||||
Name authority | Vahl | Muhl. ex Elliott | ||||||||
Web links |