Poa glauca |
Poa stebbinsii |
|||||||||
---|---|---|---|---|---|---|---|---|---|---|
glaucous blue grass, timberline bluegrass, white bluegrass |
Stebbins' blue grass |
|||||||||
Habit | Plants perennial; usually glaucous; densely tufted, not stoloniferous, not rhizomatous. | Plants perennial; 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. |
10-30(40) cm, mostly erect, with 0-1 slightly exposed nodes. |
||||||||
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 1/5 – 2/5 their length, terete, smooth and glabrous, bases of basal sheaths glabrous, distal sheath lengths 1.4-3.6 times blade lengths; collars smooth, glabrous; ligules of cauline leaves 3-8 mm, colorless, transparent, smooth, margins decurrent, apices obtuse to acuminate, ligules of the innovation leaves 2.5-6 mm; innovation blades similar to the cauline blades, 1-2 mm wide, involute, moderately thick, abaxial surfaces smooth, adaxial surfaces smooth or sparsely scabrous, sometimes sparsely hispidulous; cauline blades gradually reduced in length distally, 1-2 mm wide, folded or involute, moderately thick, soft, abaxial surfaces smooth, apices narrowly prow-shaped. |
||||||||
Basal branching | all or mostly extravaginal. |
strictly extravaginal. |
||||||||
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. |
3-7 cm, erect or slightly nodding, narrowly lanceoloid to narrowly ovoid, often interrupted, contracted to loosely contracted, with 9-38(60) spikelets; nodes with 1-2 branches; branches 0.5-1.5(2.5) cm, erect at maturity, slender, terete to sulcate or weakly angled, sparsely to moderately scabrous, with 1-5 spikelets. |
||||||||
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, lengths to 3.5 times widths, lanceolate, laterally compressed, not sexually dimorphic, usually strongly anthocyanic, less so in pistillate plants; florets 2-4; rachilla internodes smooth, glabrous or sparsely hispidulous. |
||||||||
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. |
unequal, lanceolate, thin, lustrous, distinctly keeled, keels and distal surface smooth or sparsely finely scabrous; lower glumes 3-veined, distinctly shorter than the lowest lemmas; calluses glabrous; lemmas 3.5-5.5 mm, lanceolate, distinctly keeled, thinly membranous, smooth or sparsely scabrous, glabrous, lateral veins moderately prominent, margins glabrous, apices acute; palea keels finely scabrous; anthers vestigial (0.1-0.2 mm) or 2-4.5 mm. |
||||||||
2n | = 34, 42, 44, 47, 48, 49, 50, 56, 56, 57, 58, 60, 63, 64, 65, 70, 75, 78, ca. 100. |
= 42, 81 (both counts of uncertain application). |
||||||||
Poa glauca |
Poa stebbinsii |
|||||||||
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
|
CA |
||||||||
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 stebbinsii is endemic to the high Sierra Nevada. It grows primarily in the outer margins of subalpine wet meadows, and is gynodioecious. It is easily recognized by its long hyaline ligules, thin glabrous lemmas, and the absence of intravaginal shoots. It was confused with P. bansenii Scribn. [= P. cusickii subsp. cusickii] by Keck in Munz (1959), and with P. leibergii by Hitchcock (1951). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
||||||||
Key |
|
|||||||||
Source | FNA vol. 24, p. 576. | FNA vol. 24, p. 564. | ||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Stenopoa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Epiles | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Name authority | Vahl | Soreng | ||||||||
Web links |