49 



(G. Vasey); no locality (John Wolfe 1158); Grizzly Creek (C. F. Baker 1-4); 

 Como Park (C. L. Shear 1092). ]Vi/omiii(/: Sundance (T. A. Williams 2602, 

 D. Griffiths 423); Bear Lodge (T.A.Williams 2629); Inyan Kara Momitain (d! 

 Griffiths 634); Big Horn Momitains(W. H. Forwood). South Dakota: Custer 

 (Lavid Griffiths 700) ; Elk Creek, Black Hills (P. A. Rydberg 1167); Sylvan Lake 

 (D. Griffiths 719, 70S ). Montana : Columbia Falls (R. S. Williams) ; Gallatin River 

 Canyon (J. W. Blankinship); Black Hawk (P. A. Rydberg 3271); Dry Fork Belt 

 Creek (P. A. Rydberg 3356) ; Barker (P. A. Rydberg 3362, 3383). British America: 



RockyMoimtains(J. Macounl4);FortEllice(J. Macounl04). Alberta:!^ ear Banii. 



(J. Macoun 23, 30); Benton 



Trail, :\lilk River (J. Macoun 



13051); Devils Head Lake (J. 



Macoun 25, 27 ) ; p]lbow River 



(J. Macoun 18638) ; Crow Nest 



Pass (J. Macoun 18639). Sas- 



kntcheivau : Prince Albert (J. 



3Iacoun 13050); Saskatchewan 



Plains (J. Macoun 78 ) . British 



Columbia : Kicking Horse Lake 



(J. Macoun 15). Alaska: Fort 



Yukon (O.S.Bates). 

 This plant is closely related to B. 

 erectus and also to B. inernils, 



both of which are only found 

 in this country as introducetl 

 or adventive species. Our spe- 

 cies, which is rather frequent 

 in the Rocky Mountains from 

 Coloradonorth, reaches Alaska 

 and probably connects with B. 

 ini'niiis in eastern Siberia. Our 

 plants can usually be distin- 

 guished from B. erectus by their 

 broader spikelets, longer awns, 

 and the coarse ciliate-pubes- 

 cent margins and bases of the 

 flowering glumes. The leaves 

 of the sterile shoots or innova- 

 tions of B. ('rectus are narrow 

 and involute and the plant 

 caespitose. In the case of B. 

 inermis the relationshijj is 

 closer and the separation more 

 difficult. Generally i lur species 

 has a narrower, denser, more 

 rigidly erect panicle with shorter branches and broader spikelets. The flower- 

 ing glumes are more coarsely and densely ciliate-pubescent and very rarely 

 muticous. The difficulties of separating these species are likely to be greatly 

 increased in the future by the rapid distribution of the cultivated forms of B. 

 inennis in the region occupied by B. pumpdlianus and also by the probability of 

 hyl)ridization of the two i)lants. Judging from the description and a single 

 spikelet from the type of Hooker's B. purgans purpurascens, collected by Dr. 

 Richardson in the region of Bear Lake, British America, it is the same as our 

 plant. 



20796— No. 23 4 ■ 



Fig. 29. Bromus pumpellianus : a, empty glumes with two 

 florets ; b, dorsal view of a flowering glume. 



