Poa glauca
Poa glauca subsp. glauca
glaucous blue grass, timberline bluegrass, white bluegrass
glaucous bluegrass
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.
10-40(80) cm.
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.
all or mostly extravaginal.
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.
3.5-10(20) cm.
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.
not bulbiferous;
florets normal.
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.
webbed or glabrous;
lemmas usually with lateral veins short-villous to softly puberulent, intercostal regions glabrous or short-villous to softly puberulent.
= 34, 42, 44, 47, 48, 49, 50, 56, 56, 57, 58, 60, 63, 64, 65, 70, 75, 78, ca. 100.
= 34, 42, 44, 47, 48, ca. 49, 50, 56, 60, 63, 64, 65, 70, 75, 78.
Poa glauca
Poa glauca subsp. glauca
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 glauca subsp. glauca is the widespread and common subspecies in the Northern Hemisphere. It is also disjunct in South America. Plants with glabrous calluses are found only in the arctic. In the Rocky Mountains, P. glauca subsp. glauca often grows with subsp. rupicola and P. interior (see previous). It does not grow in California, and is uncommon in the Great Basin and southern Rocky Mountains. It is highly variable, especially in the Great Lakes region. It is often confused in herbaria with subsp. rupicola, but can sometimes be distinguished by its webbed calluses and lemmas that are glabrous between the veins. The name P. glaucantha Gaud, has sometimes been applied to plants of P. glauca from southeastern Canada and the northeastern United States.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. All or some spikelets bulbiferous | var. pekulnejensis |
1. Spikelets not bulbiferous. | → 2 |
2. Calluses usually webbed, sometimes glabrous; lemmas glabrous or hairy between the veins | subsp. glauca |
2. Calluses glabrous; lemmas hairy between the veins | subsp. rupicola |
BC
OR
WA
CalFlora
Flora NW
Go Botany
MI Flora
MN Wildflowers
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
