76 



POACEAE 



nearly 2 mm. long; lemma 2.5-3 mm. long, the nerves pilose below. Waste 

 places and cultivated ground: Lab.— Ga.— Calif.— B.C.; Mex.; nat. from Eu. 

 Plain — Mont, My-0. 



2. P. Bigelovii Vasey & Scribn. Annual, usually more or less tufted; 

 ligules lanceolate, 3 mm, long; leaf-blades flat, flaccid, 5-10 cm. long, 2-4 mm. 

 wide; panicle 5-15 cm. long, narrow; spikelets 4-6 mm. long, compressed; empty 

 glumes glabrous, lanceolate, acute, nearly as long as the lemma; lemma 3-4 mm. 

 long, subacute, villous on the midrib and marginal nerves; cobweb scant. Arid 

 regions: Tex.— Colo.— Utah— Calif.— L. Calif. Son.Suhmont. 



3. P. pratensis L. Stem 3-12 dm. high, smooth; leaf-blades 1-6 mm. wide, 



those of the stem 5-15 cm. long, the basal ones longer; panicle 5-20 cm. long, 



ovate or conical; spikelets 3-6-flowered, 4-5 mm. long; midvein and marginal 



veins of the lemma silky below, the intermediate ones glabrous. Meadows, 



fields and woods: Greenl.—Fla.—Calif.— Alaska; Eurasia. Plain— Siibalp, 

 Je-Au. 



4. P, rhizomata Hitchc. Perennial, with a creeping rootstock; stem 3-6 

 dm. high, smooth; sheaths smooth, the lower loose and papery; ligules 2-3 mm. 

 long; blades mostly flat, 1-2 mm. wide, 3-7 cm. long; panicle 3-5 cm. long; 

 spikelets 3-4-flowered; first glume 3 mm. long, the second 4 mm. long; lemma 

 5 mm. long, acutish, copiously webbed at the base; keel and marginal nerves 

 short-pilose below; internerves sparingly scabrous. Damp woods: Calif.— Ida. 

 Ap-Je. 



5. P. occidentalis Vasey. 

 s; leaf -blades 5-15 cm. lone. 



ttened 



4-0 



acute, scarious margined, unequal; lemma 3-4 mm. long, slightly pubescent 

 below and on the keel; cobweb scant. P. plalyphylla Nash & Rydb. Rich 

 hillsides: N.M. — Colo.— Utah. SubmonL—Subalp. My-Au. 



6. P. callida Rydb. Stem 3-5 dm. high, somewhat flexuose; leaf-blades 

 flat, flaccid, 5-12 cm. long, about 3 mm. wide; panicle open, 1-1.5 dm. long; 

 spikelets about 3 mm. long, 2- or 3-flowered, light green; first empty glume sub- 

 ulate, 2 mm. long, the second slightly broader, 2.5 mm. long, glabrous; lemma 

 3 mm. long, glabrous except the keel, which is slightly silky below; cobweb scant 

 but long. Warm springs: Mont. Jl. 



7. P. lanata Scribn. & Merr. Perennial, with a creeping rootstock; stem 

 2.5-4 dm. high; sheath loose, the lower marcescent, scabrous; ligule 4 mm. long^ 

 obtuse; blades 2-4 mm. wide, conduplicate or involute; inflorescence open; 

 branches m pairs, 2-3 cm. long, with 1-3 spikelets near the ends; spikelets 3-6- 

 flowered; lemma purple, 6-7 mm. long. Subarctic situations: Alaska— B.C. 

 Subarct. 



8. P. cenisia All. Stem 1-3 dm. high, slender; ligules 1-2 mm. long, trun- 

 cate; blades 2-10 cm. long, 1-2 mm. wide, involute; panicle 2-8 cm, long, open; 

 spikelets 2-4-flowered, 5-6 mm. long, purplish; empty glumes glabrous; lemma 

 about 4 mm. long. Arctic-alpine situations: Greenl.— Lab.— Colo.— Alaska; 

 Eu. Alp, Jl-Au. 



9. P. arctica R. Br. Stems 1-3 dm. high, smooth, erect or decumbent at 



the base; ligules erose-truncate; basal leaf-blades 5-10 cm. long, 2-4 mm. wide; 

 stem-leaves shorter and often flat; panicle open, 5-10 cm. long; spikelets purple; 

 empty glumes 3-3.5 mm. long, glabrous; lemma 4 mm. long, acute. Alpine- 

 arctic situations: Arctic Sea— N.M .—Utah. Alp. Jl-Au. 



. ^ Ip* P- longlpila Nash. Stem 3-5 dm. high; ligules broad, obtuse or acut- 

 ish; leaf-blades erect, acuminate, 3-8 cm. long, 3-4 mm. wide, flat; panicle 6-9 

 cm. long; spikelets &-8 mm. long, 3-4-flowered, purple; lemma 5-6 mm. long; 

 cobweb copious and long. Wet places: Wyo.— Mont. Submont, 



11. P. callichroa Rydb. Perennial, with a horizontal rootstock, but more 

 or less matted; stem about 3 dm. high; blades of the lower leaves 6-10 cm. long, 

 firm, dark-green, strongly veined; blades of the upper leaves about 3 cm. long^ 



