204 



POACEAE 



17. Poa occidentalis \^asey. 

 Tall Western Bluegrass 



Fig. 469. 



Poa occidentalis Vasey, Contr. U. S. Nat. Herb. 1: 274. 1893. 

 Foa leptocoma elatior Scribn. & Merr. Contr. U. S. Nat. Herb. 

 13: 71. 1910. 



Perennial, without rhizomes ; culms rather stout, 

 erect, scabrous, 1-1.5 meters tall; sheaths somewhat 

 keeled, retrorsely scabrous ; ligule triangular. 6-8 mm. 

 long; blades flat, scabrous, 10-20 cm. long. 3-6 mm. 

 wide; panicle open, 15-30 cm. long, the branches in 

 distant whorls of threes to fives, slender, spreading or 

 reflexed, the lower as much as 10 cm. long, spikelet- 

 liearing toward the end ; spikelets 3-6-flowered ; 

 glumes acuminate, 4 mm. long ; lemmas about 5 mm. 

 long, conspicuously webbed at base, villous on lower 

 part of keel, slightly villous on lateral nerves. 



Open woods, Alaska, Oregon (Sauvies Island. Howell), 

 California (Hot Springs, Sequoia National Forest, Jar dine), 

 Colorado, Utah, and New Mexico. May. Type locality: Las 

 Vegas, New Mexico. 



18. Poa palustris L 



Fowl Meadow Grass 



Fig. 



470. 



Poa palustris L. Syst. Veg. ed. 10. 2: 874. 1759. 



Poa scrotina Ehrh. Beitr. Naturk. 6: 83. 1791 (nom. nud.) 



and later authors. 

 Poa triflora Gilib. Exerc. Phyt. 2: 531. 1792. 



Perennial, without rhizomes ; culms loosely 

 tufted, smooth, decumbent at the flattened purplish 

 base, 30-150 cm. tall; sheaths smooth; ligule 3-5 

 mm. long; blades soft, 8-15 cm. long, 2-4 mm. 

 wide ; panicle pyramidal or oblong, nodding, yel- 

 lowish green or purplish, 10-30 cm. long, the 

 branches in rather distant fascicles, naked below ; 

 spikelets 2-4-flowered, about 4 mm. long; lemmas 

 2.5-3 mm. long, villous on the keel and marginal 

 nerves, the web copious, the intermediate nerves 

 faint. 



Meadows and moist open ground, in the Transition 

 Zone; Alaska to California; Sierra Valley (Lemmon) , east 

 to Nova Scotia. June-Aug. Type locality, European. 



19. Poa alpina L. 



xA.lpine Bluegrass 



Fig. 471. 



Poa alpina L. Sp. PI. 67. 1753. 



Perennial, from a rather thick vertical caudex. with 

 no creeping rliizomes ; culms erect, comparatively stout, 

 smooth, 10-30 cm. tall ; sheaths smooth : blades short 

 and flat, smooth, 2-5 mm. wide, the uppermost often 

 very short ; panicle ovoid, rather compact, 1-4 cm. long ; 

 spikelets broad, purple or purplish-tinged ; lemmas 3-4 

 m.u. long, strongly villous on the keel and lateral 

 nerves, and pubescent below l:)etween the nerves. 



Arctic regions of the northern hemisphere, extending to alpine 

 meadows of the high mountains of Washington and Oregon 

 (Wallowa Mountains, Cnsick). July-Aug. Type locality, Euro- 

 jjean. 



Poa stenantha Trin. has been found at Crater Lake (Clemens). 

 It has flat lax blades, ligule 3-5 mm. long, open nodding panicle 

 of rather large spikelets, the lemma pubescent on the nerves but 

 without cobwebby hairs at base. Alaska to Montana. 



