1906] Lamson-Scribner, — Trisetum and Graphephorum 89 



of T. melicoideum. From the more nearly allied Trisetum altijugum 

 Scribn. n. comb. (Graphephorum alfipigum Fourn.) by its larger pani- 

 cles and spikelets which are about 4 mm. long. The panicle of T. 

 altijugum resembles that of Sporobolus iudicus. 



Trisetum montanum Vasey, Bull. Torr. Bot. Club, 13: 118, 1886; 

 r. alpestre Vasey, Bot. Wheeler Exped. 6: 294, PI 37, fig. 4, 5, 6, 

 1878 — not T. alpestre Beauv. 1812; Trisetum Shearii Scribn. U. S. 

 Dept. Agr. Div. Agros. Circ. 30: 8, 1901; Graphephorum Shearii 

 Rydb. Bull. Torr. Bot. Club, 32: 602, 1905. 



Dr. Vasey at first referred this grass to the European Trisetum alpes- 

 tre; later he noted its close relationship with T. fai'escens, and he 

 says (]MS. notes in National Herbarium): "much like T. flavescens, 

 but wanting in the color; the leaves are much longer, the spikelets are 

 smaller, the flowering glumes much more acuminate, the awns shorter 

 and less twisted." The specimens of the Wheeler Expedition (no. 

 669, J. Wolfe) are about 2.") dm. high, with rather densely flowered 

 panicles 6-8 cm. long. Robust specimens 6-10 dm. high, with more 

 open panicles 10 to 20 cm. long, are represented in the National 

 Herbarium from Liaho Falls, no. 720, C. L. Shear, and nos. 2481, 

 2484, 2491, P. A. Rydberg, 1895. It is difficult to separate these from 

 T . flavescens, the most obvious difference being in the awn, which is 

 straight or simply divergent in T. montanum, while in T. flavescens it is 

 twisted below and distinctly geniculate. The glumes, especially the 

 flowering ones, are a very little broafler in the last named species. 



The lower sheaths and leaves vary from being entirely glabrous to 

 l)ilose or pubescent, as in no. 2479, P. A. Rydberg, and no. 718, C. L. 

 Shear, 1895, both from Idaho Springs. Other specimens with the 

 lowermost sheaths pubescent come from Las Vegas, New Mexico, col- 

 lected by G. R. Vasey, and from Garland, Colorado, no. 71, C. L. 

 Shear, 1900. Variations in the length of the awn occurs in this as in 

 other species of Trisetum, and the color varies from pale silvery green 

 to purplish shades, the shortening of the awn occurring in the latter, 

 being especially manifest in no. 1214, C L. Shear, from Silverton, Colo- 

 rado, specimens that were at first regarded as representing a distinct 

 species (T. Shearii Scribn.). Other specimens showing intermediate 

 characters occur connecting the short-awned forms with the longer 

 awned types. 



The distribution of Trisetum montanum appears to be limited to the 

 mountain regions of Colorado and New Mexico. 

 Washington, D. C. 



