Poa glauca |
Poa abbreviata |
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glaucous blue grass, timberline bluegrass, white bluegrass |
abbreviated bluegrass, dwarf blue grass, northern blue grass, short bluegrass |
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Habit | Plants perennial; usually glaucous; densely tufted, not stoloniferous, not rhizomatous. | Plants perennial; not or scarcely glaucous; densely tufted, not stoloniferous, not 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. |
5-15(20) cm, slender, leafless above the basal tuft. |
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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 – 1/4 their length, terete; ligules 0.4-5.5 mm, milky white to hyaline, smooth or scabrous, apices truncate to acute; blades 0.8-1.5(2) mm wide, involute, moderately thick, soft, apices narrowly prow-shaped. |
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Basal branching | all or mostly extravaginal. |
all or mainly intravaginal. |
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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. |
1.5-5 cm, erect, lanceoloid to ovoid, contracted, congested; nodes with 1-3 branches; branches to 1.5 cm, erect, slender, terete, sulcate or angled, smooth or the angles sparsely scabrous; pedicels usually shorter than the spikelets. |
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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. |
4-6.5 mm, laterally compressed, rarely bulbiferous, frequently strongly anthocyanic; florets 2-5, rarely bulb-forming; rachilla internodes usually shorter than 1 mm, smooth or scabrous. |
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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. |
subequal to slightly longer than the adjacent lemmas, lanceolate to broadly lanceolate, distinctly keeled, keels smooth; lower glumes (1)3-veined, lateral veins often faint and short; upper glumes exceeding or exceeded by the upper florets; calluses glabrous or webbed; lemmas 3-4.6 mm, lanceolate to broadly lanceolate, distinctly keeled, thin, keels and marginal veins usually short- to long-villous, hairs extending along 3/4 - 5/6 of the keel, infrequently glabrous, intercostal regions glabrous or softly puberulent to short-villous, apices acute; palea keels scabrous, often short-villous to softly puberulent at midlength, sometimes glabrous; anthers 0.2-1.2(1.8) 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. |
= 42. |
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Poa glauca |
Poa abbreviata |
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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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AK; CA; CO; ID; MT; NV; OR; UT; WY; AB; BC; NT; NU; 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 abbreviata is an alpine and circumarctic species which has two subspecies in the western Cordilleras, and one in the high arctic. It grows mainly on frost scars and mesic rocky slopes, usually on open ground. In rare cases where the lemmas and calluses of P. abbreviata ate glabrous, it can be confused with P. lettermanii (p. 580), but that species has shorter spikelets and glumes that are longer than the adjacent florets. (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 > sect. Abbreviatae | ||||||||||||||||
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Name authority | Vahl | R. Br. | ||||||||||||||||
Web links |