GRASS FAMILY 37 



1. P, barbipulvinatum Xush. Annual; stem at length branched and root- 

 ing at the nodes; sheaths denseh' pubescent with spreading hairs, papillate at the 

 base; blades hairy on both sides, 4-13 cm. long, 5-10 mm. wide; panicles ovate, 

 1-2 dm. long; spikelets 3-3.5 mm. long; first glume less than one-half as long as 

 the spikelet, broadly ovate, 3-nerved; second and third glumes pubescent at the 

 apex. Western Witch-grass. Wet sandy soil: Minn. — Kans. — Wyo. — Ore. 

 — -B-C, Plain — Submont, Jl-S. 



2. P, capillare L. Erect or decumbent annual; stem 2-S dm. high, simple 

 or sparingly branched; sheaths papillose-hirsute; leaf-blades 1.5-3 dm. long, 5- 

 15 mm. wide, pubescent; terminal panicle 2-3.5 dm. long; lateral ones when 

 present smaller; spikelets 2-2.5 mm. long, somewhat acuminate or acute; first 

 glume 14-^2 as long as the spikelet, 5-7-nerved; second and third trlabrous. 

 Witch-crass. Dry or sandy soil and waste places: N.ri.— Fla. — Tex. — Nev. — 

 Wash.— B.C. Plain. Je-S. 



3. P. virgatum L. Perennial with a creeping, scaly rootstock; stem 1-2 m. 

 high, glabrous; sheaths smooth; leaf-blades elongated, 3 dm. long or more, (5-12 

 mm. wide, flat, rough on the margins; panicle 1.5-5 .dni. long; spikelets ovate, 

 acuminate, 4-4.5 mm. long; first glume acuminate, about half as long a.s the 

 s})ikelet, 3~5-nerved; second glume usually longer than the rest. Meadows and 

 plains. Me. — Fla. — Tex. — Ariz. — Sask.; W. Ind. and C. Am. Plain — Son. 

 Au-S . 



4. P, occidentale Scribn. Tufted perennial, yellowish green; stem 1.5-4 

 dm. high, with short lower internodes; blades 4-8 cm. long, 5-7 mm. wide, 

 glabrous or with a few hairs towards the base above, appressed-pubcscent be- 

 neath; panicle long-exserted, 4-7 cm. long, lax, with flexuose spreading branches; 

 spikelets about 1.8 mm. long, obovate, acute, pubescent; first glume one-fourth 

 as long as the spikelet or less; second and third glumes subequal, as long as the 

 fruit. Bogs and sandy ground: B.C. — Ida. — Calif. Submojit. 



5. P. tennesseense Ashe. Perennial, at first spreading; stem 2.5-6 dm. 

 high; sheaths spreading-pubescent-; leaf-blades 6-9 cm. long, often ciliate at the 

 base, glabrous or nearly so above, appressed-pubescent beneath; panicle 4-7 cm. 

 long, rather dense; spikelets 1.6-1.7 mm. long, obovate, obtuse, pubescent; first 

 glume about one-fourth as long as the spikelet; second glume shorter than the 

 third. Open moist ground: Me. — Ga. — Miss, — -Utah. Plain — Submont. 



6. P. pacificum Hitchc. & Chase. Tufted perennial; stem 2.5-5 dm. high; 

 leaf-blades 5-10 cm. long, 5-8 mm. wide, acuminate, papillose-pilose, with 

 shorter hairs intermixed, aj^pressed-pubescent beneath; panicle short-exserted, 

 5-10 cm. long, with flexuose ascending branches; si)ikelets obovate, obtuse, papil- 

 lose-pubescent; first glume one-fourth to one-third as long as the spikelet, trun- 

 cate; second and third glumes equalling the fruit. Sandy shores: B.C. — Ida. — 

 Ariz. — Calif. Plain — Submont, 



* 



?• P. Huachucae Ashe. Erect or ascending perennial, at length much 

 branched: stems 2-6 dm. high; leaf-blades lanceolate or lance-linear, acuminate, 

 pubescent beneath with short hairs, 4-10 cm. long, 5-12 mm. wide; panicle 5-10 

 cm. long, usually purplish; branches spreading, few-flowered; spikelets obovate, 

 obtuse, 1.5-1.8 mm. long; first glume small, about one-third as long as the spike- 

 let; second and third glumes equal, pubescent with spreading hairs. P. pubes- 

 cms A . Gray, not Lam. Meadows: Me. — N.C, — Calif .—Mont. Plain— Mont, 

 Jf-S. 



8, P. thermale Bolander. Tufted perennial; stem 1-3 dm. high; leaf- 

 blades lanceolate, 2-10 cm. long, 5-10 mm. wide, thick, finely and densely pubes- 

 cent on both sides, or glabrate above; terminal panicle exserted, 2-4 cm. long; 

 branches spreading, few-flowered; lateral panicles often included; spikelets 

 obovoid; first glume rounded-ovate, about one-fourth as long as the spikelet: the 

 second and third glumes pubescent. Around hot springs: Calif .—Xev,—^^ yo. 

 Mont. Mont, — Submont. Au. 



9. P, perlongum Nash. Tufted pubescent perennial; stems 2-4 dm. high, 

 simple; sheaths hirsute with long ascending hairs; leaf -blades papillose-hispid 



