§ 2. Aments lateral or terminal, with or without bracts; scales persistent, colored at the tip; stamens 2 (usually 1 in n. 19), with glabrous filaments (united and hairy in S. purpurea); shrubs or small trees.
[*] Capsules tomentose.
[+] Pedicels 3–6 times the length of the gland; style medium or none.
[++] Large shrubs or small trees (8–15° high); leaves obovate or elliptic-lanceolate, 2–4´ long, acute or acuminate, more or less obscurely and irregularly serrate, thin becoming rigid, glaucous beneath; fertile aments oblong-cylindric, 2–3´ long, loosely flowered.
5. S. rostràta, Richardson. Leaves dull green and downy above, stoutly veined and soft-hairy beneath, serrate, crenate or subentire; stipules when present semi-cordate, toothed, acute; aments appearing with the leaves, the sterile narrowed at base, pale yellow; capsules tapering to a very long slender beak; pedicels thread-like, much exceeding the pale, rose-tipped, linear, thinly villous scales; style scarcely any; stigma-lobes entire or deeply parted. (S. livida, var. occidentalis, Gray.)—Moist or dry ground, N. Eng. to Penn., and far west and northward. Not spreading from the root but having rather the habit of a small tree, with a distinct trunk.
6. S. díscolor, Muhl. (Glaucous W.) Leaves smooth and bright green above, soon smooth beneath, irregularly crenate-serrate, the serratures remote at base, closer, finer and becoming obsolete toward the point; stipules ½´ long or more, and sharply toothed, or small and nearly entire; aments closely sessile, thick, oblong-cylindrical, 1´ long or more, appearing before the leaves in earliest spring; scales dark red or brown, becoming black, copiously clothed with long glossy hairs; style short but distinct.—Var. eriocéphala, Anders. Aments more densely flowered and more silvery silky; leaves sometimes retaining a ferruginous pubescence beneath even when fully grown.—Var. prinoìdes, Anders. Aments more loosely flowered, less silky; capsules more thinly tomentose; style longer; stigma-lobes laciniate; leaves narrower. (S. prinoides, Pursh.) Includes narrow-leaved forms of the type, and others which are probably hybrids with S. cordata.—Low meadows and river-banks, common. The just expanding leaves are often overspread with evanescent ferruginous hairs.
[++][++] Upland grayish shrubs, 1–8° high; leaves oblanceolate, pointed, the lowest obtuse, downy above becoming glabrate, beneath glaucous, rugose-veined and softly tomentose, the margin revolute, undulate-entire; aments ovoid or oblong, closely sessile, appearing before the leaves, naked at base; capsules rather shortly pedicelled, greenish or reddish, spreading; scales dark red or brownish; style distinct; stigmas bifid.
7. S. hùmilis, Marsh. (Prairie W.) Leaves oblanceolate or oblong-lanceolate, the lowest obovate; stipules medium-sized, semi-ovate, entire or oftener toothed; petioles distinct; aments often recurved, about 1´ long.—Dry plains and barrens, common. A shrub, 3–8° high, varying much in the size and shape of the leaves. Hybrids with n. 6 have equally broad and large but duller green leaves, softly tomentose beneath and with shorter petioles, the aments equally thick but usually recurved, and the capsules on shorter pedicels. Small forms apparently pass into the next.
8. S. trístis, Ait. (Dwarf Gray W.) Leaves small (1–2´ long), crowded, linear-oblanceolate, tapering to a very short petiole; stipules minute, deciduous; aments very small, globular or oval, about ½´ long in fruit.—Sandy plains or on the borders of hillside thickets, common. A tufted shrub, 1–1½° high, rising from a strong large root.
[++][++][++] Low shrubs, 3–10° high, of cold swamps, with slender yellowish or reddish twigs; leaves lanceolate, smooth above, glaucous beneath and covered when young with appressed silvery-silky hairs; aments (especially the fertile) with a few leafy bracts at base; capsule pedicelled, silvery-silky; stigmas bifid.