B141 

 (leaf 2) 



willow is fairly representative of the leaf form of flrmleaf willow (8. pseudo 

 myrsini'tes), blue willow (S. subcoeru'lea) , Eastwood willow (8. eastwoo'diae), 

 and blueback willow (8. glau'cops), and of many other shrubby species. The 

 somewhat wedge-shaped leaf of Scouler willow is extraordinary, being found 

 only in the dwarf summit willow (S. saximontu'na,) and a few other species. 

 The long narrow leaf of narrowleaf willow is also characteristic of dusky 

 willow (8. melanop'ste) and silverleaf willows. 



Most mature willow leaves are green or dull green with some white hairs, 

 particularly on the under side. However, some species, as the names of satin 

 willow (8. sitchen'&is) and silverleaf willow suggest, have light-colored, densely 

 long-hairy leaves. In a few species, such as Lemmon willow, the leaves become 

 hairless, at least when mature. 



Willow plants are one-sexed (dioecious) ; their flowers are in catkins, which 

 usually emerge from the single-scaled buds before the leaves, although they 

 sometimes appear simultaneously. The pussy willow, herald of spring, is the 

 swollen male ( stamina te) flower bud or catkin, especially if silky and plump. 

 The common cultivated pussy willow of the florists, however, is the native 

 S. discolor. The catkins of the male plants become yellow when the pollen 

 matures, falling as a unit and shortly after pollen is shed. The catkins of the 

 female plants emerge green, later becoming white and soft-cottony from the 

 soft hairs attached to the tiny seed ; the entire catkin falls intact by mid- 

 summer. The tiny seeds are very short-lived, but very plentiful. 



The willows are closely related to poplars (Populus spp.), the two genera 

 composing the willow family ( Salicaceae) . The poplars are rather easily dis- 

 tinguished, although they often grow with the willows, particularly in the 

 riparian associations. The western poplars are trees, with long-stemmed, 

 usually heart-shaped, sometimes large, and mostly hairless leaves, although 

 one species, narrowleaf cottonwood (Populus anffustifolia) , has short-stemmed, 

 rather narrow, and lance-shaped leaves, and is sometimes mistaken for a wil- 

 low. Other differences, less obvious, are that the bracts of poplars subtending 

 the individual flowers are feathery-edged, the flower is on a cup-shaped disk, 

 the stamens 4-12 or numerous, and the buds composed of several overlapping 

 scales. The common Populus on the western ranges is aspen, P. tremuloides 

 a/urea (syn. P. aurea). 



Willows provide one of the principal sources of browse on many of the 

 western mountain ranges. Although the foliage is most palatable to sheep, 

 cattle probably make greatest use of these plants, because they usually range 

 where willows abound. The palatability varies according to species but, on 

 the average, willows are fair forage for cattle and good for sheep. The willows 

 are most important as a late summer feed because the foliage seemingly in- 

 creases in palatability as the season advances. At times considerable use is 

 made of the frosted and colored leaves, sheep, in particular, even eating them 

 after they have fallen. The willows are so difficult to differentiate that the 

 field man, unfamiliar with species distinctions, ordinarily fails to determine 

 their individual palatabilities. However, in a limited way, it is apparently 

 possible to place them in broad groups by the use of leaf characters. Thus spe- 

 cies, like tail-leaf willow, with relatively large, rather tough and shiny leaves, 

 are of less forage value than the smaller, soft, thin, or pubescent-leaved species, 

 such as Bebb willow. The greensides willow (S. monochro'ma) of the North- 

 west has small, thin, and dark green leaves and rates as an outstanding browse 

 willow in that section. Scouler willow is one of the most widely distributed and 

 most valuable forage willows on the western mountain ranges. 23 Its leaves, as 

 shown in the illustration, are unusual in shape for a willow ; the species is also 

 distinctive in its habitat as it seldom grows! near water courses, usually in* 

 habits open forest slopes, and frequently becomes very abundant on burns. 

 Although it usually occurs as an erect shrub about 15 feet high, occasionally 

 the species develops into a tree 30 feet in height, or taller. Even in the tree 

 forms, however, the growth ordinarily consists of a number of small stems of 



2 Sampson, A. W. IMPORTANT RANGE PLANTS : THEIR LIFE HISTORY AND FORAGE VALUE. 

 U. S. Dept. Agr. Bull. 545, 63 pp., illus. 1917. 



* Dayton, W. A. IMPORTANT WESTERN BROWSE PLANTS. U. S. Dept. Agr. Misc. Pub. 

 101, 214 pp., illus. 1931. 



