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Montana Field Guide

Montana Field Guides

Canada Bluegrass - Poa compressa

Exotic Species (not native to Montana)

Global Rank: GNR
State Rank: SNA

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value: 0

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General Description
Rhizomatous perennial. Stems 20–50 dm, wiry and flattened, nodes often distinctly bent and banded with contrasting lighter and darker bands. Leaves: blades 1.5–4 mm wide, from stem, rarely basal; ligules 1–3 mm long. Inflorescence a narrow panicle 2–8 cm long. Spikelets 3–6 mm long. Lemmas with cobwebby hairs at very base (Lavin in Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Diagnostic Characteristics
The genus Poa is distinguished by its flat leaf blades, 2-6 flowered panicles, 1-3 nerved glumes, and 5-nerved lemmas (Gleason 1957, Mohlenbrock 1972, Hitchcock 1950). Some species have a tuft of cobwebby hairs at the base.

Poa compressa is visually separated from Poa pratensis by its blue-green foliage, distinctly flat culms and narrow compact inflorescence (Gleason and Cronquist 1953, USDA 1948). Bases of the strongly keeled lemmas are less conspicuously cobwebby than on Poa pratensis (Gleason and Cronquist 1953).

Species Range
Present
 


Range Comments
Despite its common name, Canada bluegrass (Poa compressa) is undisputedly considered to be a European introduction (Hitchcock 1950, USDA 1948, Fernald 1950, Gleason and Cronquist 1953).

Introduced throughout most of North America (Lavin in Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).


Summary of Observations Submitted for Montana
Number of Observations: 40

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat
Roadside, road cuts, trailside, along ditches, and on open slopes and other open site with a combination of moisture and regular moderate disturbance (Lavin in Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

References
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Citation for data on this website:
Canada Bluegrass — Poa compressa.  Montana Field Guide.  .  Retrieved on , from