260 TREES OF MINNESOTA. 
full development of the leaves in May or June. A genus of about 
twenty species of soft wooded trees, mostly natives of cold ch- 
mates, one-half of which are found in North America. 
Populus tremuloides. Aspen. American Aspen. Quak- 
ing Asp. Poplar. Popple. 
Leaves ovate or obicular, with a sharp, short apex, small, 
smooth on both sides; petiole long, flattened. Flowers in April 
before the leaves in hairy catkins. Fruit a small, two-valved 
capsule; seeds very small. Bark smooth, greenish white except 
on very old trees; twigs not angular. This is generally a small, 
short-lived tree, but occasionally it grows sixty or more feet 
high. The pendulous leaves tremble in the slightest breeze; the 
silver gray bark is attractive and the autumn color of the leaves 
is one of the purest golden yellows found among trees. 
Distribution.—From Southern Labrador to southern shores of 
Hudson Bay, to the Mackenzie and Yukon rivers, south to 
Pennsylvania, Missouri, New Mexico and Lower California and 
through all mountain ranges of the West. One of the most 
widely distributed trees of North America. In Minnesota it is 
found throughout the state, and is very common on cut-over tim- 
ber lands, where it is generally the first tree to take possession 
of the land after the pine is cut off. It grows most luxuriantly 
along the borders of swamps and open forest glades. The seed 
is carried long distances by the wind. 
Propagation.—By seeds, which grow freely; but the seeds, 
however, are seldom sown in nurseries, as the hmited demand 
for this species is easily supplied by the seedlings which spring 
up along the lake shores and sand bars. 
Properties of Il’vod.—Light, soft, not strong, close grained, of 
cottony fiber, and soon decays in contact with the soil. It is of 
a light brown color, with thick, nearly white, sapwood. Specific 
gravity, 0.4032; weight of a cubic foot, 25.13 pounds. 
Uses.—On account of the color of the bark and the autumn 
color of the leaves an occasional specimen of Aspen can be used 
to advantage to give variety to our tree plantings. Although it 
grows rapidly when young, it is of very slow growth when older, 
he wood is used for paper pulp, and occasionally for interior 
finishing and for turnery. It makes good light fuel if cured 
under cover. 
