E-Flora BC: Electronic Atlas of the Flora of British Columbia

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

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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

Source: The Illustrated Flora of British Columbia

Habitat / 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.

Source: The Illustrated Flora of British Columbia


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) 1800 2193 2500
Slope Gradient (%) 0 40 97
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
20 166 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
1 3 5
Modal Nutrient Regime
Number 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)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Poa cusickii var. epilis (Scribn.) C.L. Hitchc.
Poa epilis Scribn.
Poa purpurascens var. epilis

Taxonomic and Nomenclatural Links

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General References