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Broadleaved Trees of Yosemite National Park (1947) by C. Frank Brockman


WILLOWS

Salix spp. — Willow Family — (Salicaceae)

Although about fifteen species of willows are native to Yosemite National Park, where they are found growing from the low foothill zone to the frigid upper slopes of the Sierra peaks within the Arctic-alpine Zone (1), but three species can be considered as attaining tree stature. These are the Pacific willow (Salix lasiandra Benth.), also known as the yellow or western black willow, the red willow (Salix laevigata Bebb.), also known as the polished or smooth willow, and the Scouler willow (Salix scouleriana Barrett). The first named is perhaps the most common. It can be readily found along the banks of the Merced River in Yosemite Valley (2).

This is a difficult group of plants and the person not trained in botany will have difficulty in determining the various species. However, as a group they possess certain well defined and readily recognized characters with which most people are familiar and which can be readily noted even by casual observation. Thus, to most people the identity of “willow” is usually sufficient and this group is treated in that fashion.

Typical willow foliage (Inch squares on background)
[click to enlarge]
Photo by Brockman

Typical willow foliage (Inch squares on background)

(1) Alpine willow (Salix petrophila caespitosa) is one of the more interesting high altitude plants of Yosemite National Park. It is rarely more than 4-6 inches high and can be found on moist slopes in the vicinity of timberline.

(2) Three others—the heartleaf willow (Salix cordata), the arroya willow (Salix lasiolepis), and the Hind’s or sandbar willow (Salix hindsiana) sometimes assume the stature of tall shrubs and may occasionally be regarded as small trees.


All willows are deciduous trees or shrubs with simple, alternate leaves. The staminate (male) and pistillate (female) flowers are borne on different trees in narrow, elongated clusters known as catkins. The fruit is a capsule which contains many seeds, each bearing a tuft of hairs at the base, by means of which the seeds are dispersed by the wind. The bark has a bitter, quinine-like flavor. The leaves, which are generally elongated, have a pair of peculiar earshaped growths (stipules) at the base of the leaf stems. The buds are distinctive in that they are characterized by a single bud scale. The leaf scars, left upon the twigs after the foliage has dropped in the autumn, are U-shaped and narrow with three vascular bundle scars upon the surface. The buds, with their single scale, and the leaf scars are particularly good characters for winter identification.

The twigs of various species of willow were once widely used by the Indians of the Yosemite region in the manufacture of many types of baskets.

For detailed, specific descriptions of the various species of willows found in this region the reader is referred to the several texts noted in the list of selected references on page 40.



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