ON POPULUS TREMULOIDES. 
275 
ART. XL.— ON POPULUS TREMULOIDES. 
By Laurence Turnbull. 
(Extract from an Inaugural Essay < J 
The vulgar names of this species are, While Poplar and 
American Aspen. The Aspen is common in all the northern 
and middle States. It prefers open lands of a medium qua- 
lity; its ordinary height is about thirty feet, and five or six 
inches in diameter. The bark is greenish and smooth, except 
at the bases of the old trees, when it becomes furrowed and 
very rough; it blooms about the first of April, ten days or 
two weeks before the birth of the leaves. The aments which 
spring from the extremity of the branches are composed of 
silky plumes, of an oval form, about an inch in length ; the 
leaves are about two inches broad, narrowing at the summit, 
and supported by long petioles; they are of a dark green co- 
lor in the spring. The nerves are reddish, in stalks of seven 
or eight inches in height; they are nearly round, and bor- 
dered with obtuse, irregular teeth; on the young shoots they 
are twice the size, heart shaped, and acuminate at the summit. 
Of all the American Poplars, this species has the most tremu- 
lous leaves; the gentlest air is sufficient to throw it into agi- 
tation. The wood is light and soft. The Populus Grandi- 
dentata very much resembles the Populus Tremuloides, but it 
is a larger tree ; it is from forty to fifty feet in height, and in 
the spring the leaves are covered with a white down, which 
falls off in the beginning of summer. These two species are 
easily confounded; and I owe the means of detecting them to 
the kindness of Mr. Nuttall. 
PROPERTIES. 
All parts of the American Aspen possess bitter and tonic 
properties. The bark appears to be the portion in which 
VOL. VIII. — NO. iv. 35 
