MANUAL OF THE GRASSES OF THE UNITED STATES 



115 



to 15 cm. long, the lower branches in 

 whorls of 3 or 4; spikelets 3- or 4- 

 flowered, 5 to 6 mm. long; lemmas 

 about 4 mm. long, webbed at base, 

 rather sparsely pubescent on lower 

 part of the nerves. % — Moist 

 woods, southeastern Alaska (Cape 

 Fox, Hot Springs), Sol Due Hot 

 Springs, Olympic Mountains, Wash. 

 Sauvies Island (near Portland), Oreg. 

 18. Poa pratensis L. Kentucky 

 bluegrass. (Fig. 132.) Culms tufted, 

 erect, slightly compressed, 30 to 100 

 cm. tall; sheaths somewhat keeled; 

 ligule about 2 mm. long; blades soft, 

 flat or folded, mostly 2 to 4 mm. wide, 

 the basal often elongated; panicle 

 pyramidal or oblong-pyramidal, open, 

 the lowermost branches usually in a 

 whorl of 5, ascending or spreading, 

 naked below, normally 1 central long 

 one, 2 shorter lateral ones and 2 short 

 intermediate ones; spikelets crowded, 

 3- to 5-flowered, 3 to 6 mm. long; 

 lemmas copiously webbed at base, 

 silky-pubescent on lower half or two- 

 thirds of the keel and marginal nerves, 

 the intermediate nerves distinct, gla- 

 brous. % — Open woods, mead- 

 ows, and open ground, widely dis- 

 tributed throughout the United States 



and northward, except in arid regions, 

 found in all the States (but not com- 

 mon in the Gulf States) and at all al- 

 titudes below alpine regions; intro- 

 duced from Europe. Bluegrass is 

 commonly cultivated for lawns and 

 pasture in the humid northern parts 

 of the United States. 



19. Poa cuspidata Nutt. (Fig. 133.) 

 Culms in large lax tufts, 30 to 50 cm. 

 tall, scarcely longer than the basal 

 blades; blades lax, 2 to 3 mm. wide, 

 abruptly cuspidate-pointed ; panicle 7 

 to 12 cm. long, open, the branches 

 mostly in pairs, distant, spreading, 

 spikelet-bearing near the ends; spike- 

 lets 3- or 4-flowered; lemmas 4 to 6 

 mm. long, tapering to an acute apex, 

 webbed at base, sparingly pubescent 

 on the keel and marginal nerves, the 

 intermediate nerves distinct, gla- 

 brous. % (P. brachyphylla Schult.) 

 — Rocky woods, New York, New 

 Jersey to Ohio, south to Georgia and 

 Alabama. 



20. Poa arida Vasey. Plains blue- 

 grass. (Fig. 134.) Culms erect, 20 to 

 60 cm. tall; blades mostly basal, firm, 

 folded, usually 2 to 3 mm. wide, a 

 single culm leaf usually below the 

 middle of the culm, its blade short; 



Figure 133. — Poa cuspidata. Panicle, X 1; floret, 

 X 10. (Smith 27, Pa.) 



Figure 134. — Poa arida. Panicle, X 1; floret, X 10. 

 (Jones, Colo.) 



