Whitebark Pine (Pinus albicaulis).—Very difficult to distinguish from limber pine, although needles are more rigid and slightly curved. Needles are from 1½ to 2½ inches long. Cones are from 1½ to 3 inches long and of a dark purple color. The bark is chalky-white. This tree is found at elevations of from 8,500 to 10,000 feet, or slightly above the limber pine. It is not as important for commercial use as are the other pines.
Lodgepole Pine (Pinus contorta).—Needles are 1½ to 2 inches long, yellow-green, growing in bundles of two. Bark is thin. Cones are one-sided, 1½ to 2 inches long, and cling to the branches for years without opening or dropping their seeds. Cone scales are armed with short spines. This species is used mostly for railroad ties, mine props, and telephone poles.
SPRUCES.—Spruces have sharp-pointed, four-sided needles scattered over the twigs singly, leaving twigs rough like a grater when they fall off. There is only one spruce on the Shoshone Forest.
Engelmann Spruce (Picea engelmanni).—The new-growth twigs are covered with soft, short hair. Needles are less rigid and less sharply pointed than those of blue spruce, green, dark blue, or pale steel-blue. Cones are 1 to 2 inches long. Bark is dark, reddish brown, and separates in the form of small, rounded scales. Main trunk, in contrast to blue spruce, is smooth and clean.
FIRS.—Needles are blunt, flat, and soft to the touch, without any stem where they join branches. They leave flat, round scars when they fall off in contrast to short stubs left by spruce on twigs. Cones, unlike those of other species, stand erect. In the fall, the cones fall to pieces and leave only spikes on the branch. Buds are blunt and pitchy. Blisters, containing liquid pitch or balsam, are scattered over the smooth bark.
Alpine Fir (Abies lasiocarpa).—Leaves are flat, 1 to 1¾ inch long, without any stem where they join the branches. Needles tend to turn upward. Cones are 2½ to 4 inches long, dark purple. The bark is gray and smooth, except in older parts of the tree where it is broken into ridges. Tree has a sharp, spirelike crown. It usually grows mixed with Engelmann spruce.
DOUGLAS FIR (Pseudotsuga taxifolia).—Although similar in name, this species has no direct relationship to the true fir. Its leaves are flat, ¾ to 1½ inches long, with short stems that join them to the branches. Cones are pendent, with three-pronged bracts protruding from the cone scales; they are persistent and fall off the tree whole. Buds are sharp-pointed, shiny, smooth, red brown.
CEDARS.—Rocky Mountain Red Cedar (Juniperus scopulorum).—The berries are about the size of peas, the bark is scaly, the twigs are slender and graceful, and the heartwood is red. The species is distinguished from the one-seed juniper in that its berry usually has two seeds and is bluish or black. The berries mature in 2 years.
BROADLEAF TREES.—Aspen (Populus tremuloides).—Aspens are commonly called “quaking aspens” or “quakers.” The flat, nearly heart-shaped leaves are about 2 inches across; they tremble characteristically in a breeze. The bark is whitish or very pale green, smooth with black scars where branches have dropped off. The trees rarely grow more than 50 feet high.
Narrowleaf Cottonwood (Populus augustifolia).—This is usually a tall tree, 40 to 60 feet high. The bark is dark gray, heavily ridged half or two-thirds of the way up the tree; above that, smooth and pale green. The leaves are ½ inch to 1 inch wide by 2 or 3 inches long, very similar to willow leaves. The species is usually found along streams at lower elevations.