AMENTACEOUS PLANTS. 337 
ceous ; it grows in the High Alps and the Pyrenees, in Mount Doré 
in Auvergne, and also in the Grampians. Willows are diccious; 
their flowers are in catkins, and solitary, with an axil to each scale 
of the catkin. They have no envelopes. Figs. 375 and 876 
Fig. 377.—Male Flowers of Salix alba. Fig. 378.—Female Flower of Salix alba. 
represent the male and female catkins of the Willow ; 377 and 378 
show the isolated flowers. » 
The Poplars (Populus) are nearly allied to the Willows, and in 
the flowers they are only distinguished from them by the greater 
number of stamens, which are inserted on the internal face of a 
kind of cup. : 
The Black Poplar (Populus nigra) is among the larger of these 
trees, commonly known as the Swiss Poplar. The White Poplar 
(Populus alba), a fine tree with ample cyme, is furnished with 
ves remarkable for their extreme whiteness underneath, especially 
Upon the most elevated shoots. Fig. 879 represents this species. 
The Aspen (Populus tremula) is the only real forest-tree of this 
genus; it is of middle height, with leaves which are very mobile 
_ lM consequence of their length; they are compressed vertically, 
___ Which leads to'the horizontal tremulous motion which distinguishes 
the tree and procured its name. ; 
The Pyrammar Portar, originally from the Caucasus and 
P ersia, was imported into Italy and France about the year 1749; 
it is remarkable for its erect branches which spring from nearly the 
base of the trunk, and altogether form a long, straight, pyramidal _ . 
“yme: only the male plant of this species is known. | 
Among the Amentales the CasvARINEACES are for the most 
. ge 
