GRAMINEAE. 141 



scales about 4 mm. long, obtuse, pilose for half their length, pubescent between the 

 nerves toward the base. Lab. to Alaska, south to Quebec, Lake Superior, and in 

 the Rocky Mts. to Colo. Also in Europe and Asia. Summer. 



19. Poa compressa L. WIRE-GRASS. FLAT-STEMMED MEADOW-GRASS. 

 ENGLISH BLUE-GRASS. (I. F. f. 461.) Pale bluish green, glabrous. Culms 

 1.5-6 dm. tall, decumbent at the base, from long horizontal rootstocks, much 

 flattened; sheaths loose, flattened, shorter than the internodes; leaves 2.5-10 cm. 

 long, about 2 mm. wide, smooth beneath, rough above; panicle usually contracted, 

 the branches erect or ascending, 2.5 cm. long or less, spikelet-bearing nearly to the 

 base; spikelets 3-g-flowered, 3-6 mm. long; lower scales acute, 3 nerved; flower- 

 ing scales 2-2.5 mm - ' on g> obscurely 3 -nerved, the nerves sparingly pubescent 

 toward the base. Waste places and cultivated grounds and woods almost through- 

 out N. Am. Ascends to 630 jn. in Va. Naturalized from Europe. Native also 

 of Asia. Varies from weak and slender to quite stiff. June-Aug. 



20. Poa arachnifera Torr. TEXAS BLUE-GRASS. (I. F. f. 47ga.) Culms 

 tufted, 39 dm. tall, from running rootstocks; sterile shoots from one-half as long 

 as the culms to equalling them. Leaves linear, erect, usually folded when dry, 

 smooth beneath, rough above, 3.5-22.5 cm. long, 3-6 mm. broad, abruptly acute; 

 panicle dense and contracted, sometimes interrupted below, 7.5-16 cm. long, 

 1.25-3.75 cm. broad, its branches ascending or erect; spikelets numerous, 4-7- 

 flowered, the scales acuminate; flowering scales 4-5 mm. long, often pointed, 

 pubescent at the base with copious long cobwebby hairs, 5-nerved, the midnerve 

 and lateral nerves pilose below the middle. Prairies, Kans. to N. Mex., south to 

 La. and Tex. Also introduced in Fla. April-May. 



21. Poa glumaris Trin. LARGE-FLOWERED SPEAR-GRASS. (I. F. f. 480.) 

 Culms 1.5-9 dm. tall, erector assurgent. Sheaths loose; leaves 1-2.5 dm. long, 

 2 8 mm. wide; panicle 1-2.5 dm. i n length, the branches erect or ascending, 



5-5 cm. long; spikelets 3~5-flowered, 8-12 mm. long; flowering scales 6-8 mm. 

 long, usually acutish, scabrous, 5~7-nerved, pubescent at base and on the lower 

 part of the midnerve and lateral nerves, not webbed. Anticosti Isl. and N. S. to 

 Quebec and Alaska. Summer. 



22. Poa arida Vasey. PRAIRIE SPEAR-GRASS. (I. F. f. 478). Culms 3-6 

 dm. tall, erect, rigid. Sheaths usually overlapping; ligule 2-4 mm. long, acute; 

 leaves smooth beneath, rough above, 1-2 mm. wide, flat or folded, pungently 

 pointed, those of the culm 1.25-2.5 cm. long, erect, the basal leaves 7.5-15 cm. 

 long; panicle contracted, 5-12.5 cm. in length, the branches erect, spikelet-bearing 

 nearly to the base, 3.75 cm. long or less; spikelets 4-7 -flowered, 5-7 mm. long ; 

 flowering scales 3-4 mm. long, erose-truncate at apex, strongly silky-pubescent on 

 the nerves for half their length, the lower part very pubescent between the nerves; 

 intermediate nerves very obscure. Meadows and low grounds, N. W. Terr, to 

 Kans. and Ariz. April-Aug. 



23. Poa Buckleyana Nash. BUCKLEY'S SPEAR-GRASS. (I. F. f. 479.) 

 Culms 1.5-4 dm. tall, rarely taller, erect, rigid. Ligule 4-6 mm. long, acute; 

 leaves 2.5-10 cm. long, about 2 mm. wide, erect, flat, or becoming involute, smooth 

 or rough; panicle 2.5-10 cm. in length, contracted, the branches erect, 3.75 cm. 

 long or less, spikelet-bearing nearly to the base; spikelets 2-5-flowered. 4-6 mm. 

 long; flowering scales about 4 mm. long, obtuse or acutish, appressed-pubescent be- 

 low, with long hairs. Usually in dry soil on mountain slopes or elevated prairies, 

 S. Dak. to Br. Col., Colo, and Cal. May-Sept. 



24. Poa lucida Vasey. Culms 6-8 dm. tall, erect, the innovations 2-3 dm. 

 long; sheaths smooth and glabrous; leaves of the culm I dm. or less long, those on 

 the innovations much longer; panicle 1-2 dm. long, its larger branches 3-5 cm. 

 long; spikelets 6-10 mm. long, 4-6-flowered, the flowering scales about 4.5 mm. 

 long, appressed-pubescent below with long hairs, obtuse or acutish. Moist hill- 

 sides andmeadcws, Mont, to Neb. and Colo. June-Aug. 



25. Poa laevigata Scribn. Culms densely tufted, 6-8 dm. tall, erect, slender, 

 the innovations 1-2 dm. long; sheaths smooth and glabrous; leaves I dm. or less 

 long; panicle very slender, 8-14 cm. long, its larger branches 3-5 cm. long; spike- 

 lets 5~7 mm. long, 3 4-flowered, the flowering scales 3-4 mm. long, hispidulous all 

 over, obtuse to ftcutish. dry hills, Mont, to Neb, and Colo. June-Aug. 



