GRASS FAMILY 77 



erect; pa'nicle 6-9 cm. long, open; spikelets 6-8 mm. long, 5-7-flpwered; empty 

 glumes about 5 mm. long, purple with greenish or brownish margins; lemma 4-5 

 mm. long, lanceolate, acuminate, green below, then purple, then brown, and 

 white and scarious above; nerves and internerves more or less villous; cobweb 

 scant. Mountain peaks: Colo. -Wyo. Subalp. Mont. Au. 



12. P. pudica Rydb. Stem 2-3 dm. high; lower leaves with short loose 

 sheaths; ligules truncate, about 2 mm. long; blades 4-5 cm. long, usually con- 

 duplicate, strongly nerved; panicle 4-8 cm. long; spikelets 4-5 mm. long, mostly 

 3-flowered; empty glumes strongly veined, usually purple, acuminate; lemma 

 lanceolate, sharp-acuminate, greenish below, then purplish, and scarious at the 

 apex. Alpine meadows: Colo. Subalp. Alp. Au. 



13. P. reflexa Vasey & Scribn. Stem 3-5 dm. high, slender, erect, smooth; 

 ligules 2 mm. long, obtuse; leaf-blades 5-15 cm. long, 2-4 mm. wide; panicle 

 5-10 cm. long; spikelets 2-3-flowered, 3-4 mm. long, usually purple; empty 

 glumes acuminate, smooth; lemma very acute. Wet meadows: Alta. N.M. 

 Utah Ore. B.C. Submont. Subalp. 



14. P. nervosa (Hook.) Vasey. Stem 4-7 dm. high, slender, smooth; 

 ligules truncate; blades of stem-leaves 2-7 cm. long, 2-4 mm. wide; those of the 

 basal leaves 1.5-2.5 dm. long; panicle 5-12 cm. long, open; spikelets 3-8-flowered, 

 flat, lax and flexuose; empty glumes linear-lanceolate, 4 mm. long; lemma linear- 

 lanceolate, slightly scabrous on the nerves. Wet places: B.C. Calif. Mont. 

 Mont. Subalp. 



15. P. leptocoma Trin. Stems 3-6 dm. high, smooth; ligules obtuse; leaf- 

 blades flat, flaccid, 1-3 mm. wide, 4-10 cm. long; panicle open, 5-10 cm. long; 

 spikelets 2-3-flowered, about 6 mm. long, green or merely tinged with purple; 

 first empty glume about 3 mm. long, the second 3.5 mm. long; lemma linear- 

 lanceolate^ gradually acute. Boggy places: Alta. Colo. Wash. Alaska. 

 Mont. Subalp. Jl-Au. 



16. P. alpicola Nash. More or less tufted perennial; ligules acute, 2 mm. 

 long; leaf -blades 3-10 cm. long, often involute or conduplicate, 1-2 mm. wide; 

 inflorescence rather narrow, 3-5 cm. long; branches short; spikelets 5-7 mm. 

 long, 2-4-flowered, more or less tinged with purple; empty glumes subequal, 

 glabrous, about 3 mm. long; lemma ovate, acute, glabrous. P. laxa Thurber, 

 not Haenke. Alpine: Colo. Utah (? Ida.) Alp. Jl-Au. 



17. P. compressa L. Perennial, with a creeping rootstock; stem 1.5-4 

 dm. high, decumbent at the base, much flattened, smooth; ligules truncate; 

 leaf-blades bluish green, stiff, erect, 2-10 cm. long, about 2 mm. wide, often 

 convolute, scabrous above; panicle narrow, with ascending short branches, 

 spikelet-bearing to near the base; spikelets 3-5-flowered, 3-9 mm. long; empty 

 glumes acute, nearly equal; lemma 2-2.8 mm. long, obtuse; cobweb scant. 

 Waste places, cultivated grounds, and woodlands: N.H. N.C. Calif. B.C. 

 Yukon; Eurasia. Plain Mont. Je-Jl. 



18. P. aperta Scribn. & Merr. Stem 4-5 dm. high, erect, wiry; ligules 

 acute; leaf-blades firm, striate, minutely scabrous, glaucous, 5-15 cm. long, 

 2 mm. wide; panicle ovate; spikelets purplish, 5-6 mm. long, 3-4-flowered; 

 lemma lanceolate, minutely pubescent throughout; cobweb conspicuous. Moun- 

 tains: N.M. Wyo. Mont. Subalp. Au-S. 



19. P. macroclada Rydb. Stem 6-8 dm. high; ligules ovate, acute; leaf- 

 blades 7-10 cm. long, 2 mm. or less wide, flat, glabrous, firm and dark green; 

 panicle 2-3 dm. long, open; spikelets often about 5 mm. long; lemma lanceolate, 

 acute or acuminate, glabrous, slightly purple-tinged; cobweb scant. Moun- 

 tains: Colo. Mont. 



20. P. triflora Gilib. Perennial, with a creeping rootstock; stem 4-12 dm. 

 high, erect, smooth; leaf-blades 5-15 cm. long, 2-5 mm. wide; panicle 1.5-3 dm. 

 long, open; spikelets 3-5-flowered, 3-5 mm. long; empty glumes glabrous, scab- 

 rous on the keel; lemma obtuse, 2-3 mm. long; midnerve and lateral nerves 

 pubescent below. P. serotina Ehrh. P. flam Auth., not L. Meadows and 

 swampy places: Newf. N.J. Calif. B.C.; Eurasia. Plain Mont. Jl-Au. 



