258 



GRAMINEAE. 



Vol. I. 



16. Poa Wolfii Scribn. Wolf's Spear-grass. 

 Fig. 619. 



Poa Wolfii Scribn. Bull. Torr. Club 21 : 228. 1894. 



Culms 2°-3° tall, erect, slender, simple, smooth and 

 glabrous. Sheaths shorter than the internodes; ligule 

 i" long; blades 1" wide or less, smooth beneath, rough 

 above, those of the culm 2'-4' in length, the basal much 

 longer; panicle 3'-6' in length, lax, its branches erect or 

 ascending, flexuous, ii'-24' long; spikelets 2-4-flowered, 

 2i"-3" long; scales acute, the lower unequal, 3-nerved, 

 glabrous, rough on the keel, the first shorter than the 

 second ; flowering scales about 2" long, copiously webbed 

 at the base, 5-nerved, the marginal and midnerves silky- 

 pubescent for more than half their length, the interme- 

 diate nerves prominent, naked. 



Illinois to Minnesota and Tennessee. 



17. Poa brachyphylla Schult. Short-leaved Spear-grass. Fig. 620. 



Poa brevifolia Muhl. Gram. 138. 1817. Not DC. 1806. 

 Poa brachyphylla Schult. Mant. 2: 304. 1824. 



Culms i°-3° tall. Sheaths often shorter than the 

 internodes; ligule 4"— ij" long; leaves smooth be- 

 neath, rough above, l"-2" wide, abruptly acute, those 

 of the culm ¥-4' long, the uppermost sometimes 

 almost wanting; basal leaves usually equalling or 

 nearly as long as the culm ; .panicle 2i'-s' in length, 

 open, the branches ascending, widely spreading or 

 often reflexed, 1I-3' long, spikelet-bearing at the 

 ends; .spikelets 3-6-flowered, 2i"-3l" long; empty 

 basal scales unequal, acute, glabrous, the lower 

 i-nerved, the upper 3-nerved ; flowering scales slightly 

 webbed at the base, 2"-2i" long, obtuse, Swerved, 

 the keel and marginal nerves sparingly pubescent, 

 the intermediate nerves prominent, naked. 



In rocky woods, southern New York to Illinois, 

 Georgia and Tennessee. April-June. 



18. Poa cenisia All. Arctic Spear-grass. Fig. 621. 



Poa cenisia All. Auct. Fl. Ped. 40. 1789. 



Smooth and glabrous, culms 4'-i5' tall, erect, slender, 

 simple. Sheaths shorter . than the internodes ; ligule 

 1" long or less, truncate; blades i'-4' long, i"-i" wide; 

 panicle i'-4' in length, open, the branches generally 

 widely spreading and more or less flexuous, i'-2i' long; 

 spikelets 3-5-flowered, 2j"-3i" long; lower scales acute 

 or acuminate, 1-3-nerved ; flowering scales about 2" 

 long, faintly 5-nerved, the nerves short-pilose on the 

 lower half, minutely pubescent between the nerves, 

 somewhat webbed at the base. 



Greenland and Labrador to Alaska, south in the higher 

 peaks of the Rocky Mountains to Colorado. Also in Europe. 

 Summer. 



