Poa compressa, Canada bluegrass

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Intermountain Flora
Rhizomatous perrenials; culms 2-5 (8) dm tall, scattered strongly flattened and 2-edged, decumbent at the base and often geniculate at the nodes, wiry, bluish-green throughout; sheaths open to near the base, strongly compressed with the flat enclosed culms so as to appear winged; lungules 0.5-1.5 (2) mm long, fairly stiff, mostly entire, rounded to nearly truncate; blades flat to folded, 1.5-3.5 mm broad, relatively short, the tips boat-shaped; panicles 3-7 (9) cm long, usually compact, dense and narrow but occasionally becoming somewhat open; spikelets 3-6 (7.5) mm long, crowded on short branches, often appearing nearly sessile, mostly 3- to 7-flowered; glumes subequal, 1.8-2.7 (3.2) mm long, the first glume 1- to 3-nerved, the second broader, 3-nerved; lemmas (2) 2.5-3 mm long, firm, sometimes nearly coriaceous, strongly keeled, obtusish, usually purplish near the tip, the keel and marginal nerves with sericeous hairs, especially toward the base, the web lacking or if presesnt than very scant; anthers 0.9-1.7 mm long; lodicules barely exceeding 0.5 mm; 2n = 14, 35, 39, 42 (the usual number), 45, 49, 50, 56.

Cronquist, A., Holmgren, A.H., Holmgren, N.H., Reveal, J.L., and Holmgren, P.K. (1977) "Intermountain Flora" pg. 228-230, vol. 6, The New York Botanical Garden New York.