I38 FLORA. 



Basal leaves very long, the early ones frequently as long as the 

 culms. 15. P, brevifolia. 



a. Rootstocks short and stout; no stolons. 



Ligule acute, 4 mm. long; flowering scales lanceolate, 3 mm. long. 



17. P, pseudopratensis. 

 Ligule truncate, 2 mm. long; flowering scales ovate, 4 mm. long. 



18. P. alpina. 

 b. Panicle contracted or spike-like. 



Internerves of the flowering scale very pubescent below with long appressed 

 hairs, the remainder appressed-hispidulous. 

 Flowering scale erose-truncate at the apex, the nerves strongly silky pu- 

 bescent below. 22. P. arida. 

 Flowering scale obtuse or acute at the apex, the nerves not silky pubes- 

 cent. 

 Innovations short, usually less than 6 cm. long; culms generally 4 



dm. or less tall. 23. P. Buckleyana. 



Innovations long, usually exceeding 2 dm. long ; culms commonly 6 

 dm. or more tall. 24. P. lucida. 



Internerves of the flowering scale appressed-hispidulous all over. 



25. P. laevigata, 

 B. Culms not tufted ; rootstocks long, creeping. 



Flowering scales naked or with short hairs at the base. 



Culms compressed, slender; plant bluish green; spikelets 3-6 mm. long. 



19. P. compressa. 

 Culms not compressed, stout; spikelets about 1 cm. long. 



21. P. glumaris. 

 Flowering scales with webby hairs at the base longer than the scale. 



20. P. arachnifera. 



1. Poa annua L. Annual Meadow-grass. Low Spear-grass. (I. F. f. 459.) 

 Culms 5-30 cm. tall, from an annual root, erect or decumbent at the base, some- 

 what flattened, smooth. Sheaths loose, usually overlapping; leaves I.25-IO cm. 

 long, 1.5-3 mm. wide, smooth; panicle 1. 25-10 cm. in length, open, branches 

 spreading, 6-35 mm. long, naked at the base; spikelets 3-5 -flowered, 3-5 mm. 

 long; lower scales smooth, the first narrow, acute, 1 -nerved, about two thirds as 

 long as the broad and obtuse 3-nerved second one; flowering scales 2.5-3 mm - 

 long, distinctly 5 -nerved, the nerves pilose below. In waste and cultivated places 

 nearly throughout N. Am. Naturalized from Europe. Native also of Asia. Mav- 

 Oct. 



2. Poa Chapmaniana Scribn. Chapman's Spear-grass. (I. F. f. 460.) 

 Culms 7.5-15 cm. tall, erect, from an annual root, simple, rigid, smooth and gla- 

 brous. Sheaths tight, mostly at the base of the culm; leaves 1.25-2.5 cm. long, 

 2 mm. wide or less, smooth; panicle 2.5-5 cm. in length, the branches usually 

 erect, sometimes spreading or ascending, 1.8 cm. long or less, naked at the base; 

 spikelets 3-7-flowered, 2.5-3 mm. long; lower scales about equal, 3-nerved, acute; 

 flowering scales webbed at the base, obtuse, 3-nerved, sometimes with two addi- 

 tional obscure nerves, the prominent ones sometimes pilose for three-fourths their 

 length. In dry soil, Ky. and Tenn. to Fla. and Ala. April-May. 



3. Poa abbreviata R. Br. Low Spear-grass. (I. F. f. 462.) Culms 1-5 

 dm. tall or less. Sheaths and leaves crowded at the base of the culm ; leaves 1. 25- 

 2.5 cm. long, I mm. wide; panicle contracted, 1.25-2.5 cm. long, branches very 

 short and erect; spikelets 3-5-flowered, 5 mm. long; lower scales acute, smooth 

 and glabrous; flowering scales about 3 mm. long, obtuse, strongly pubescent all 

 over, the intermediate nerves very obscure. Arctic America from Greenland and 

 Lab. to the Pacific. Summer. 



4. Poa laxa Haenke. Wavy Meadow-grass. Mountain Spear-grass. 

 (I. F. f. 463.) Culms 3 dm. tall or less, erect, simple. Leaves 2.5-7.5 cm. long, 1-2 

 mm. wide, acuminate ; panicle 2.5-7.5 cm. in length, the branches usually erect, 

 sometimes ascending, 2.5 cm. long or less; spikelets 3-5-flowered, 4-5 mm. long; 

 lower scales usually 3-nerved, acute, glabrous, rough on the keel at its apex; flow- 

 ering scales 3-3.5 mm. long, obtuse, 3-nerved, or sometimes with an additional pair 

 of obscure nerves, the midnerve pilose on the lower half, rough above, the lateral 

 ones pilose for one-third their Length. Greenland to Alaska, south to the mountains 

 of N. E., to Manitoba and in the Rocky Mts. to Colo. Also in Europe and Asia. 

 Summer. 



