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DECIDUOUS TREES. 113 
Popuits TREMULOIDES (American Aspen, *haking Pop- 
lar, ete.).—Leaves nearly heart-shaped, with long, slender 
stem; the peculiar form of leaf and stem allows them to 
vibrate with the slightest breeze; tree thirty to forty feet 
high; common in low grounds in most of the Northern 
States. 
Porutus GRANDIDENTATA (Large-toothed -Aspen).— 
Leaves roundish ovate, with large tooth-like notches in the 
edges, woolly pubescent when young, becoming smooth in 
summer; tree medium to large ; wood soft and very light 
when seasoned ; Northern States and Canadas. 
PopuLus HETEROPHYLLA (Various-leaved Poplar).— 
Leaves very similar to the last, but more variable in shape ; 
tree of rather larger growth, often sixty to seventy feet 
high; common at the South; rare in the more Northern 
States. 
PopuLus MONILIFERA (Cottonwood).—Leaves broadly 
heart-shaped ; young branches angled; a large tree with 
soft, light-colored wood, of very rapid growth; its large 
foliage makes it quite a fine ornamental tree ; very common 
in all the Western States, especially in Illinois. 
Porutus aneuLata (Angled Cottonwood).— Leaves 
large, broadly heart-shaped, smooth, serrate with incurved 
teeth ; young branches acutely angled, almost winged; a 
large tree ; common at the West and Southwest. 
PorvuLUS BALSAMIFERA (Balsam Poplar, Taemahac). 
—Leaves ovate, gradually tapering to a point; young 
branches round, smooth; buds large, covered with a fra- 
grant resinous matter in the spring, hence its name; often 
used for medicinal purposes; found only in the more 
