200 



POACEAE 



5. Poa compressa L. 



Canada Bluegrass. Fig. 457. 



Poa comlvcssa L. Sp. PI. 69. 1753. 



Perennial from creeping rhizomes ; culms not tufted, 

 geniculate-ascending, flattened, wiry, bluish green, 15-45 

 cm. tall ; panicle narrow, 3-7 cm. long, the usually short 

 branches in pairs, spikelet-bearing to the base; spikelets 

 crowded, subsessile, 3-6-flowered. 4-6 mm. long : glumes 

 about 2 mm. long, 3-nerved ; lemmas firm, obscurely nerved, 

 2-2.5 mm. long, spariixgly webbed at base, short-pubes- 

 cent below on keel and marginal nerves. 



Open ground, open woods, meadows, and waste place? throvighout 

 the United States; introduced from Europe. June-Aug. Type 

 locality: Euroije. 



6. Poa macrantha \'asey. 

 Seashore IHuegrass. Fig. 458. 



Poa maciantha Vasey, Bull. Torrey Clulj 15: 11. 1888. 



Perennial, from extensively creeping rhizomes ; 

 culms erect from a decumbent base, 15-40 cm. tall, 

 the sterile shoots widely spreading ; sheaths smooth, 

 tawny and papery; blades smooth, involute, more or 

 less curved or flexuous; panicle narrow, contracted, 

 sometimes dense and spike-like, 5-12 cm. long, pale 

 or tawny ; spikelets large, about 12 mm. long, about 

 5-flowered; glumes smooth, 3-nerved, or the second 

 indistinctly 5-nerved, about 8 mm. long; leinmas 8 

 mm. long ; not webbed at base, short-pilose on the 

 keel and marginal nerves below, slightly scabrous 

 on the keel above and sparingly on the back near 

 margins ; palea ciliate on keels. 



Sand dunes along the coast, Washington to Eureka, Cali- 

 fornia. June-July. Type locality : mouth of Columbia River. 



7. Poa douglasii Xees. 



Douglass Uluegrass. 



Fig. 459. 



Poa douglasii Nees, Ann. Nat. Hist. 1: 284. 1838. 



Perennial from extensively creeping rhizomes; 

 culms ascending from a decumbent base, usu- 

 ally less than 30 cm. tall ; sheaths smooth, 

 tawny and papery ; blades involute, some of 

 these usually exceeding the culm ; panicles dioe- 

 cious, ovoid or oblong, dense and spike-like, 

 2-5 cm. long, nearly 1 cm. wide, pale or 

 tawny ; spikelets 6-10 mm. long, about 5-fiower- 

 ed ; glumes broad, 3-nerved, smooth, scabrous 

 on upper part of keel, nearly equal, 4-6 mm. 

 long ; lemmas 6 mm. long, slightly webbed at 

 base, villous on the lower part of keel and 

 marginal nerves, scabrous on keel above, 1-3 

 pairs of indistinct intermediate nerves ; palea 

 ciliate on keels. 



Sand dunes near the coast. Point Arena to Monterey. 

 Ai)r.-July. Type locality: "California." 



