Poa cusickii subsp. epilis Vasey (Scribn.) W.A. Weber
Cusick's bluegrass
Poaceae (Grass family)

Introduction to Vascular Plants


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E-Flora BC Static Map

Distribution of Poa cusickii subsp. epilis
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Species Information

Perennial, densely tufted grass from fibrous roots; stems erect or decumbent, 10-50 cm tall/long.
Sheath margins open 1/4-3/4 their length; sterile shoots emerging inside sheaths, or also breaking through sheath bases; blades 0.5-2 mm wide, those of sterile shoots in-rolled, moderately thick, outer surface smooth or rough, inner surface usually distinctly rough or minutely soft-hairy, leaf blades of lateral shoots folded to in-rolled and rough to more or less stiff-hairy on and between the veins of the upper surfaces; ligules of sterile shoots 0.5-2.5 mm long, the tips blunt to rounded, the backs rough.
Inflorescence of mostly erect panicles, 2-12 cm long, mostly congested, lanceolate to egg-shaped, the branches 1 to 2 per node, appressed or steeply ascending, moderately strict, smooth or rough; spikelets strongly laterally compressed, (3) 4-8 (10) mm long, 2- to 6-flowered; glumes unequal, the lower ones 3.5-5 mm long, 3-nerved, the upper ones 4.5-6 mm long; rachillas smooth or rough; lemmas lanceolate to broadly lanceolate, 4-7 mm long, the tips sharp-pointed, surface membranous, smooth or rough, hairless (or keel and marginal nerves minutely soft-hairy below in ssp. purpurascens), lateral nerves obscure to prominent; calluses hairless (or short, sparsely cobwebby in ssp. purpurascens); palea keels rough; flowers usually unisexual; anthers vestigial, aborted late in development, or 2-3.5 mm long.
Three subspecies occur in BC. These include two female, apomictic subspecies (ssp. epilis and ssp. purpurascens) and a sexual, although often apomictic subspecies (ssp. Pallida).

1. Basal tuft of leaves dense, basal shoots arising from within the sheaths, lacking bladeless leaves below; all stem nodes enclosed in the sheaths or the uppermost barely exposed; stem leaf blades similar to, or somewhat broader than those of the basal shoots, rarely flat, blades of basal shoots more or less threadlike, mostly less than 1 mm wide when expanded................ ssp. pallida Soreng

1. Basal tuft of leaves looser, basal shoots, in part, arising externally to the sheath, with bladeless leaves below; at least one stem node well exserted and exposed at maturity; stem leaf blades frequently wider than those of the basal shoots, and flat or folded, basal shoot blades up to 3 mm wide when expanded.

2. Lemmas of at least some of the lower florets of some spikelets very sparsely to moderately hairy on the base of the keels and frequently with a few hairs on the calluses; panicles loosely contracted and with less than 20 spikelets..................... ssp. purpurascens (Vasey) Soreng

2. Lemmas of all florets smooth to rough; panicles tending to be compact, strict, and with more than 20 spikelets................... ssp. epilis (Scribn.) Weber

SourceThe Illustrated Flora of British Columbia


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Ecological Framework for Poa cusickii ssp. epilis

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres)
2193 1800 2500
Slope Gradient (%)
40 0 97

Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]

166 20 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
3 1 5
Modal Nutrient Regime
# of field plots
 species was recorded in:
Modal BEC Zone Class

All BEC Zones (# of stations/zone) species was recorded in

AT(18), BAFA(2), ESSF(9), IMA(5)

Habitat and Range

Dry to mesic meadows, talus slopes and ridges in the montane to lower alpine zones; ssp. epilis - frequent throughout BC; ssp. pallida - infrequent in SE BC; ssp. purpurascens - frequent in SC and SW BC; ssp. epilis - E to AB and S to CO, UT, NV and CA; ssp. pallida - N to S YT, E to MB and S to ND, CO, UT, NV and CA; ssp. purpurascens - S to CA.

SourceThe Illustrated Flora of British Columbia


Synonyms and Alternate Names:
Poa cusickii var. epilis (Scribn.) C.L. Hitchc.
Poa epilis Scribn.
Poa purpurascens var. epilis