208 



GRAMINEAE. 

 20. Poa arida Yasey. Prairie Spear-grass. (Fig. 478.) 



Poa andina NutL ; S. Wats. Bot. King's Exp. 388. 1871. Not 



Trin. 1836. 

 Poa arida Vasey, Contr. U. S. Nat. Herb, i: 270. 1893. 



Culms i-2 tall, erect, rigid, simple, smooth and gla- 

 brous. Sheaths usually overlapping, smooth or some- 

 what roughish; ligule i // -2 // long, acute; leaves smooth 

 beneath, rough above, ^ // -i // wide, flat or folded, pun- 

 gently pointed, those of the culm Yz'-\ f long, erect, the 

 basal leaves 3 / -6 / long; panicle contracted, 2 / -5 / in 

 length, the branches erect, spikelet-bearing nearly to the 

 base, I YZ' long or less; spikelets 4-7-flowered, 2%"-$%" 

 long; lower scales nearly equal, acute, 3-nerved; flower- 

 ing scales i^ // -2 // long, erose-truncate at apex, strongly 

 silky-pubescent on the nerves for half their length, the 

 lower part very pubescent between the nerves; interme- 

 diate nerves very obscure. 



On prairies, Kansas to Utah, north to British America. 

 July-Sept. 



21. Poa Buckleyana Nash. Buckley's Spear-grass. (Fig. 479.) 



Poa tenuifolia Buckley, Proc. Acad. Phila. 1862: 96. 1862. 



Not A. Rich. 1851. 

 Poa Buckleyana Nash, Bull. Torr. Club, 22: 465. 1895. 



Culms 6 / -2 tall, erect, rigid, simple, smooth and 

 glabrous. Sheaths shorter than the internodes; ligule 

 2 //_y/ long, acute; leaves \ f -\ f long, about i" wide, 

 erect, flat, or becoming involute, smooth or rough; 

 panicle i / ~4 / in length, contracted, the branches erect, 

 !>' long or less, spikelet-bearing nearly to the base; 

 spikelets 2-5-flowered, 2 // ~3 // long; scales acute, the 

 lower nearly equal, scabrous on the keel; flowering 

 scales about -2" long, obtuse or acutish, sparingly 

 pubescent on the nerves below, sometimes slightly 

 hispid toward the base between the nerves. 



Kansas to California, north to British America. 

 Aug. 



July- 



22. Poa glumaris Trin. Large- flowered Spear-grass. (Fig. 480. ) 



Poa glumaris Trin. Mem. Acad. St. Petersb. (VI.) i: 379. 

 1831. 



Smooth and glabrous, culms f>'-$ tall, erect or as- 

 surgent, simple. Sheaths loose, usually shorter than 

 the internodes; ligule %" long, truncate; leaves 

 4 / -io" long, i "-4" wide; panicle 4 / -io / in length, the 

 branches erect or ascending, i / -2 / long; spikelets 3-5- 

 flowered, 4 // -6 // long; lower scales about equal, acute, 

 slighty scabrous on the keel, the first i-3-nerved, the 

 second 3-nerved, rarely 5-nerved; flowering scales 3"- 

 4" long, usually acutish, scabrous, 5-y-nerved, pubes- 

 cent at base and on the lower part of the midnerve and 

 lateral nerves, not webbed. 



Anticosti Island and Nova Scotia to Quebec and Alaska. 

 Summer. 



