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Trees of Yosemite (1932, 1948) by Mary Curry Tresidder

[Willow Family]

Black Cottonwood

Popular trichocarpa T. & G.

Black Cottonwood Branch About 1/2 Natural Size

The Black Cottonwood is one of the trees frequently encountered along the banks of the Merced River and on the edge of the meadows throughout the floor of Yosemite Valley. It is found well into the next zone also, where it finds favorable conditions, but it does not go so high as the aspen.

It grows quite tall, ranging from a rather symmetrical tree of forty feet in height, with clustering branches angling upward around the main stem, to a height of a hundred feet or more, with a rather cylindrical outline of branches and foliage. The trunk may be from one to three feet in diameter, with a smooth, whitish bark, until the tree is fairly old, when it gradually darkens and is furrowed into long, narrow plates. It is one of the broad-leaved trees which carries the main trunk through the tree.

The leaves are smooth, and are a deep, shiny green above; below they are dull in finish, whitish in color, and are quite heavily veined. In shape they are from ovate to lanceolate, varying in length from two or three inches to almost a foot. They are often heart-shaped at the base, and usually taper to a more or less acute point. They turn a deep yellow in autumn.

Staminate and pistillate flowers are usually borne on different trees and fertilization is by means of insects. The seeds are enmeshed in a cottony substance which is easily blown upon the wind and gives them a wide distribution.

Along with others of the willow family, the cottonwoods have been invaded by the oyster-shell scale and are dying off rapidly. They are also subject to a dry rot, so that old trees readily topple over in a high wind.

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