Poa glauca
Poa leibergii
glaucous blue grass, timberline bluegrass, white bluegrass
Leiberg's blue grass
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.
5-35 cm tall, 0.5-0.7 mm thick, erect or the bases decumbent, with 0-1 exserted nodes.
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 2/5 – 4/5 their length, terete, smooth and glabrous, bases of basal sheaths glabrous;
collars smooth, glabrous;
ligules (1)2-4 mm, colorless, transparent, smooth, margins decurrent or not, apices truncate to acute, ligules of innovation and cauline leaves alike;
innovation blades smooth or sparsely scabrous abaxially;
cauline blades 0.5-1 mm wide, flat, folded, or involute, thin, lax, filiform, usually soon withering, both surfaces smooth or sparsely scabrous, apices narrowly prow-shaped.
all or mostly extravaginal.
intravaginal.
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(8) cm, erect to lax, lanceoloid to ovoid or pyramidal, contracted to open, sparse, with (1)6-17(22) spikelets;
nodes with 1-2 branches;
branches 1-4 cm, erect to spreading, slender, terete, smooth or sparsely to rarely moderately densely scabrous, with 1-2(3) 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.
4-8 mm, lengths to 3 times widths, broadly lanceolate to broadly ovate, laterally compressed, not sexually dimorphic;
florets 2-8;
rachilla internodes glabrous.
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.
thin, somewhat lustrous, distinctly keeled;
lower glumes 3-veined, distinctly shorter than the lowest lemmas;
calluses glabrous;
lemmas 3.5-7 mm, lanceolate, distinctly keeled, thinly membranous, smooth or scabrous, glabrous, lateral veins moderately prominent to prominent, margins glabrous, apices acute to truncate and erose;
palea keels smooth or scabrous, glabrous or pectinately ciliate;
anthers vestigial (0.1-0.2 mm) or 1.3-3 mm.
= 34, 42, 44, 47, 48, 49, 50, 56, 56, 57, 58, 60, 63, 64, 65, 70, 75, 78, ca. 100.
= unknown.
Poa glauca
Poa leibergii
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 leibergii grows on mossy ledges and around vernal pools and the outer margins of Camassia swales, in sagebrush desert to low alpine habitats, especially where snow persists. It is found primarily on and around the basaltic Columbia plateaus, and is gynodioecious. All reports of P. leibergii from California, and most of those from Nevada, are based on misidentified specimens of P. cusickii subsp. cusickii (p. 560) and P. stebbinsii (p. 564).
(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
