HORDEAE • 155 



72. SITANION Raf. 



Some of the empty glumes 2-cleft from about 



the middle lobes abruptly divergent. caespitosum. 



Sheaths not villous. 



Sheaths consi.lcuoui3ly villous. 2. «. moUe. 



Empty glumes all entire, awl shaped. 

 Flowering glumes about 7 mm. long, soft r>ubiflorum. 



pubescent. "'• " ' ., ,• „ 



Flowering glumes glabrous about 10 mm. long. 4. S. longirolxum. 



1. Sitanion caespitosum J. G. Smith. Known only from 

 the t\Te locality in southwesteni New Mexico in the Upper Sonoran 



Zone. 



2. Sitanion moile J. G. Smith. In the mountains of the 

 west central part of the State in the Transition Zone. 



3. Sitanion pubiflorum J. G. Smith. On the high plains 

 and in the foothills of the mountains at various places throughout 

 the State. It is probably tolerably common but has been overlook- 

 ed: in the Upper Sonoran Zone. 



4. Sitanion longifolium J. G. Smith. As used here this 

 covers both the species named and S. brevifolmm of the same 

 author Fhich would seem to be hardly sufficiently distinct. They 

 form the bulk of what older authors called Elymus sitanion and 

 Sitanion ehjmoides. The species is common everywhere through- 

 out the State in arroyos, foothills and the drier parts of the moutt 

 tains in the Sonoran Zones and occasionally in the Transition. 



The Sedge Family (Cyperaceae) contains tho^sc 

 plants mostly known as Sedges and, as well, has a number of 

 other species in it that go under the name of Spike Rush, or 

 Bull Rush or varioMS other kinds of rushes but do not belong 

 with the true rushes (Junaceae) considered farther on. The 

 Cyperaceae are most nearly like grasses except for the dif- 

 ferences given below, and many of them superficially appear 

 much like grasses. Grasses have their leaves arranged in two 

 rows (2-ranked) up and down the stem while the sedges 

 have them in three. The grasses have the sheaths open at 



