75 



unilateral suhsessile spikes, the lower flowers perfect ; outer glumes 

 unequal, the outer one small, the upper longer, wider, convolute, 

 many nerved, acute ; flowering glumes longer, more rigid, closely 

 convolute, terminated in a straight, slender awn, upper flowers grad- 

 ually smaller and empty ; palet narrow, membranaceous, two-keeled, 

 bifid, closely inclosed in its glume. 



1. S. crinita, Beauv. This is credited to the Southern United States 

 by Grisebach, but we have not seen it. 



Pleueopogon, R. Br. 



Spikelets in a long, simple raceme, many-flowered, long, com- 

 pressed ; the rhachis smooth, zigzag, disarticulating under each 

 flower at maturity ; outer glumes shorter than the lowest flowers, 

 unequal, membranaceous, the lower one-nerved, the upper three- 

 nerved, awnless ; flowering glumes much longer, narrow, herba- 

 ceous to subcoriatfeous, with a smooth rounded callus at the base, 

 prominently seven-nerved, truncate or bifid at the apex, the niid- 

 nerve terminating in a straight awn; palet nearly as long as its 

 glume, strongly two-nerved, two-keeled. 



1. P. Calif ornicum, Benth. (Lophochlsena Californica, Gr.) Cali- 



fornia. 



2. P. refractum, Benth. (Lophochlsena refracta, Gr.) California 



and Oregon. 



3. P. Sabinii, Brown. Melville Island, Arctic America. 



TJnioi.a, Linn. 



Spikelets closely many-flowered, very flat and two-edged, one or 

 more of the lowest flowers neutral and consisting only of an empty 

 glume; glumes lanceolate, complicate-keeled, rigid or coriaceous, 

 the flowering ones larger, many-nerved, usually acute or pointed, 

 entire; palet rigid, two-keeled, the keels narrowly winged. Sta- 

 mens 1 to 3. 



1. II. gracilis, Michx. Common. 



2. 0. latifolia, Michx. Common. 



This a handsome grass, growing 2 to 3 feet high, with very broad 

 leaves and a spreading panicle ; the drooping spikelets larger than 

 those of any other grass we have, being an inch long or more, and 

 nearly half as wide, consisting of ten to twelve flowers. It grows 



