From the Bulletin of the Torrev Botanical Club, 36: 531-541. 1909 



Studies on the Rocky Mountain flora — XIX 



Per Axel Rydberg 



Muhlenbergia squarrosa (Trin.) comb. nov. 



Vi'fa squarrosa Trin. Mem. Acad. Petersb. VI. Sci. Nat. 5^: 100. 



1840. 

 Vilfa dcpaitperata Torr. in Hook. Fl. Bor.-Am. 2: 257. 1840. 



Not MuJilc7ibcrgia depaiipcrata Scribn. 1884. 

 Sporohohis dcpaupcratiis Scribn. Bull. Torrey Club lo : 63. 1883. 



The group of grasses which Torrey, Trinius, and Thurber 

 included under the generic name Vilfa has been transferred from 

 Sporobolus to MitJdeubergia. 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, squarrosa 

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

 is already a Muhloibcrgia depaupcrata Scribn. 



Agrostis atrata sp. nov. 



A somewhat tufted perennial; stems 1.5-3 <^'^''- '""'g^i. f^w- 

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

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

 5-10 cm. long, about 2 mm. wide, 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. TJiurbcriana, but it differs from that species 

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

 in A. aequivalvis, abruptly acute or acuminate ; the inflorescence 

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

 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. acqui- 

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



531 



