Studies on the Rocky IVIountain flora — XIX 



Per Axel Rydberg 



Muhlenbergia squarrosa (Trin.) comb. nov. 



Vilfa squarrosa Trin. Mem. Acad. Petersb. VI. Sci. Nat. 5^: 100. 



1 840. 

 Vilfa depatiperata Torn in Hook. Fl. Bor.-Am. 2: 257. 1840. 



Not Muhlenbergia depatiperata Scribn. 1884. 

 Sporobohis depauperatits Scribn. Bull. Torrey Club 10 : 63. 1883. 

 The group of grasses which Torrey, Trinius, and Thurber 

 included under the generic name Vilfa has been transferred from 



r 



Sporobohis to Muhlenbergia. See Bull. Torrey Club 32 : 599, 600. 

 As this species is a member of that group, it also should be trans- 

 ferred. It is doubtful which of the two specific names, sqiiai^rosa 

 or depatiperata is the older, but the latter is not available, as there 

 is already a Muhlenbergia depatiperata Scribn, 



Agrostis atrata sp. nov. 



A somewhat tufted perennial; stems 1.5-3 d^- high, few- 

 leaved, more or less bulbous at the base ; sheaths glabrous, shorter 

 than the internodes; hgules ovate, 1.5-2.5 mm. long; leaf-blades 

 5-10 cm. long, about 2 mm, wade, flat, smooth ; panicle 5-8 cm. 

 long, rather open; branches ascending, the lower ones 2-3 cm. long; 

 spikelets dark purple, about 2 mm. long; empty glumes nearly 

 equal, abruptly acute or acuminate; flowering glume nearly as 

 long, obtusish ; palet slightly shorter and more than half as broad. 



The type number of this species was determined by Professor 

 A. S. Hitchcock as A. Thirberiana^ but it differs from that species 

 in the following respects : The empty glumes are dark purple as 

 in A, aeqiiivahis, abruptly acute or acuminate ; the inflorescence 

 is short and open and the stem is few-leaved. In A. Thurberiana 

 the empty glumes are green, only tinged with purple at the apex, 

 narrowly lanceolate and gradually acute ; the inflorescence is long 

 and narrow, and the stem is very leafy. It differs from A. aeqiii- 

 vahis in the smaller spikelets, only 2 mm. long, instead of 3 mm., 



531 



