FOREST—TREES OF THE UNITED STATES. 29 
continent which attains a tree size. It grows from 20 to 30 feet high, 
with a thick black bark. On the Pacific coast are several species which 
become tree willows. 
No. 323. Salix nigra, var. Purshiana.—Willow.—Texas. 
No. 324. Salix longifolia, Muhl., var.—California Long-leaved Willow. 
——California. 
No. 325. Salix Wrightiana, Aud.—Wright’s Willow.—Texas. 
No. 326. Salix lasiolepis, Benth. Willow.—California. 
No. 327. Salix lucida, Hook., var.—California Shining Willow.—C€al- 
ifornia. 
No. 328. Populus tremuloides, Michx.—American Aspen.—LHastern 
United States and Rocky Mountains. A small tree of the northern 
border and Canada, also found on mountain-sides through the Rocky 
Mountains. 
No. 329. Populus grandidentata, Michx.—Great-toothed Aspen.— 
Eastern United States. This is a larger tree than the preceding, common 
in the Northern States, and extending southward along the Alleghany 
Mountains. It much resembles the European Silver Poplar. 
No. 330. Populus monilifera, Ait.—Cottonwood.—Eastern United 
States and Rocky Mountains. This and the next species of cottonwoods 
have a wide range throughout most parts of the United States. Some 
botanists consider them to be but forms of one species. They are large, 
rapidly-growing trees, particularly abundant in the prairie regions and 
western river-banks, extending even to the Pacific Ocean. The wood is 
light atid soft, much employed in some of the Western States for build- 
ing purposes, and for inside work of houses, under the name of White- 
wood and Cottonwood. 
No. 331. Populus angulata, Ait.—Cottonwood.—-Southern States. 
No. 332. Populis heterophylla, L.—Swamp Cottonwood.—Eastern 
United States. This species prevails in the Southern States, but extends 
northward as far as Delaware and Southern Illinois. It is a large tree, 
growing chiefly in swampy woods, and little valued. 
No. 333. Populus balsamifera, L.—Balsam Poplar.—Northern and 
Western United States. This species grows mostly in northern latitudes, 
being found in New England and Northern New York, also in the | 
Rocky Mountains. It is a large tree; a variety of itis in cultivation. 
No. 334. Populus angustifolia, James.—Willow-leaved Cottonwood.— 
Rocky Mountains. This is now considered to be a variety of the pre- 
ceding. Itis found principally along streams in the Rocky Mountains, 
where it is called Cottonwood, sometimes Willow-leaved Cottonwood. 
No. 335. Populus trichocarpa, Torr.—Cottonwood.—California. 
CONIFER. 
No. 336. Pinus Banksiana, Lamb.—Banks’s Pine; Scrub Pine.—Wis- 
consin to New England. This species is found from the northern 
parts of the United States nearly to the Arctic Ocean, and from Labra- 
dor to the Saskatchawan. In Wisconsin it becomes a middle-sized tree, 
and is used for timber when the trees are found of sufficient size. 
No. 337. Pinus contorta, Dougl._—Twisted pine.—Rocky Mountains. 
This tree is found in the Rocky Mountains from Colorado to Oregon. 
It differs widely in regard to size in different localities. Near the Paci- 
fic coast it is often low and scrubby, bearing cones at 5 feet high. In 
poe” it is found at an altitude of 7,000 feet, and attains a height of 
) feet. 
No. 338. Pinus contorta, Doug., var. Bolanderi.—Bolandei’s Pine.— 
