BULLETIN 
OF THE 
TORREY BOTANICAL CLUB 
ee ee 
JULY -t652 
Studies on the Rocky Mountain flora—XXVII 
; PER AXEL RYDBERG 
SALICACEAE 
PoPpuLUs HAsTAaTA Dode, Extr. Mon. Gen. Populus (Mém. Soc. 
Hist. Nat. Autun 18:) 64. 1905 
Some years ago we were forced to admit one of Dode’s species, 
P. Sargentii. say forced, because Dode’s paper is presented 
in such an unscientific way that any one might feel inclined to 
ignore it altogether. His differentiations are based wholly on the 
leaf forms, and in very few genera do the leaves show so great 
Variation asin Populus. In working over Mr. Butler’s collection of 
Montana plants I found numerous specimens of a poplar which 
has usually been regarded as P. balsamifera L., sometimes as 
‘P. trichocarpa T. & G. A study of the fruit shows that this poplar 
has the sessile and 3-carpellary fruit and the large involucral cup 
of P. trichocarpa, but the capsule is proportionally longer than in 
uilat species and perfectly glabrous. The eastern P. balsamifera 
has evident pedicels and almost always 2-carpellary ovary and 
Much smaller involucral cup. The leaves are usually broader 
than in P, balsamifera and often subcordate at the base. They 
_Fesemble much those of P. candicans Ait. in outline but are per- 
"y glabrous. P. candicans has also pediceled and 2-carpellary 
“apsules, It is apparent that this species represented by Butler’s 
material is P. hastata of Dode, for he associated it with P. tricho- 
ad and pointed out just the characters by which it differs from 
Species. The name hastata was given in reference to the 
(The Buttery for June 1912 (39: 257-300. pl. 21-23) was issued 10 Jl 1912.] 
: 301 
