Rydberg: Studies on the Rocky Mountain flora 303 



PopuLUS Fremontii Torr. 



The known range of this species was extended last summer, 

 when it was collected by Professor A. O. Garrett and the writer 

 in and around the town of Moab, southeastern Utah; and speci- 

 mens evidently also belonging to it were seen in the Cottonwood 

 and White canyons about lOO miles farther southwest. 



Willow hybrids are not uncommon in Europe and rather 

 common in cultivation; but we find very rarely any references to 

 any spontaneous hybrids of American species mentioned. It will 

 therefore not be out of place to record the following specimens 

 probably representing hybrids, although no definite proof can be 

 given of their origin. 



Salix cordata X S. monticola 



The shrubs referred here have capsules shorter than in 5. 

 cordata Muhl. but longer than in S. monticola Bebb; the habit 

 and the bark are those of the latter; but the narrow leaves 

 (although less serrate) and the bractlets are those of S. cordata 

 angustata (Pursh) Anders., the form of S. cordata common in 

 the Rockies. The capsules of the specimens seen usually re- 

 mained undeveloped. The staminate catkins resemble most 

 those of S. monticola. S. monticola was growing mixed in with 

 the supposed hybrid. 5. cordata angustata is also growing in the 

 Big Cotton Canyon, although no specimens of it were noticed 

 in the immediate vicinity where the plants were collected. 



Utah: Big Cottonwood Canyon, below Silver Lake, July ii, 

 1905, Rydberg 6877, 6878, and 6883; July 4, 1905, Rydberg & Carlton 

 6615. 



Salix glaucops X S. monticola 



The specimens resemble S. glaucops Anders, in the capsules 

 and bractlets, but the former are less densely hairy; the leaves 

 are more like those of ^. monticola, being finely serrate, glabrate 

 in age and glaucous beneath; the young branches are somewhat 

 villous. Both S. monticola and S. glaucops are growing in the 

 Big Cottonwood Canyon. 



Utah: Big Cottonwood Canyon, Salt Lake City County, 

 August 23, 1905, A. 0. Garrett 1671. 



