46 MONTANA AGRICULTURAL COLLEGE SCIENCE STUDIES. 



Populus balsamifcra caudicans, Coulter, Man. R. M. Bot. 339, 

 and others as to the Rocky Mountain species. P. candicaus, Aiton 

 is found in the United States only in cultivation or localities adja- 

 cent, to which it has escaped. The true P. balsamifcra, L. has a 

 somewhat smaller but similar leaf, quite glabrous beneath, and is 

 common in the mountains from 4000 to 6000 ft. altitude. The ''lance- 

 leaf" cottonwood, often mistaken for balsamifcra, is a hybrid between 

 balsamifcra and angustifolia and is found only where the other two 

 species occur. P. angustifolia, James occupies a somewhat lower al- 

 titude along the eastern side of the Continental Divide intergrading 

 above with balsamifcra and below with dcltoidcs. 



Populus trichocarpa, Hook. This is the common cottonwood 

 west of the Divide. The leaves are very similar to those of P. bal- 

 samifera and hence the two have been confused in this state, but 

 the fruit is woolly, instead of glabrous, like the latter. In 

 the typical tricJwcarpa the leaves are thicker, the veins more salient 

 beneath and the apex more acuminate than in balsamifcra, while 

 they are conspicuously yellow or brownish white beneath, instead 

 of greenish white, as in the latter. Along the Clark's Fork and its 

 tributaries P. tricJwcarpa is frequent in the valley lands and is a tree 

 of noble proportions with a straight trunk, branched mainly near the 

 top and with thick, deeply furrowed, whitish bark. 



Missoula, July 31, 1903; Libby Creek, July 26, 1900; Columbia 

 Falls, July 20, 1901; Flathead Lake, July 23, 1900: Saltese, Aug. 9. 

 1901; Troy, July 25, 1900; Belton, July 27, 1900; St. Ignatius, Sept. 

 7, 1899; Deer Lodge, Sept. 5, 1899. 



Salix Barrattiana Tweedyi, Bebb. (W. W. Rowlee). 

 Spanish Peaks, July 20, 1901, Jacob Vogel. 



Salix bella, Piper, Bull. Torr. Bot. Club, 27: 399. -(C. V. 

 Piper). Columbia Falls, May 25, 1893, R. S. Williams, 972. This was 

 referred to S. Sitchcnsis, Samson by Rydberg (Flora, 472), but this 

 and several other species have since been separated from it. 



Salix exigua, Nutt. (W. W. Rowlee). Separated from S. 

 longifolia, M-uhl. Bozeman, June 26, 1899; Garrison, Sept. 4, 1899. 



Salix exigua virens, Rowlee, Bull. Torr. Bot. Club, 27:255. 



Salix Fernaldii, n. sp. 



Leaves elliptical, rarely ovate, rounded at apex and base ; 

 sometimes acute at apex, 4 cm. long by two wide, 



