1. S. nìgra, Marsh. (Black Willow.) Leaves narrowly lanceolate, very long-attenuate from near the roundish or acute base to the usually curved tip, often downy when young, at length green and glabrous except the petiole and midrib; stipules large, semicordate, pointed and persistent, or small, ovoid and deciduous; fruiting aments (1½–3´ long) more or less dense; capsules ovate-conical, shortly pedicelled.—Banks of streams and lakes, bending over the water; common.—Var. falcàta, Torr. Leaves narrower and scythe-shaped—Var. Wárdi, Bebb. Leaves broader, often 1´ wide, glaucous and veined beneath; stipules large, round-reniform; aments long, loosely flowered; capsules globose-conical, long-pedicelled. Rocky islands of the Potomac (Ward); Falls of the Ohio (Short); Mo. The leaves alone are easily mistaken for those of n. 14.—A hybrid of this species with S. alba, var. vitellina, is found in Wayne Co., N. Y. (E. L. Hankenson).
2. S. amygdaloìdes, Anders. Leaves lanceolate or ovate-lanceolate, 2–4´ long, attenuate-cuspidate, pale or glaucous beneath; petioles long and slender; stipules minute, very early deciduous; fertile aments becoming very loose in fruit from the lengthening of the slender pedicels.—Central N. Y. (Dudley) to Mo.; common westward.
[++][++] A shrub or small bushy tree, 6–15° high, with smooth bark and rather stout polished twigs; petioles glandular; sterile aments thick, oblong-cylindrical, densely flowered; stamens commonly 5; scales dentate, hairy at base, smooth above.
3. S. lùcida, Muhl. (Shining W.) Leaves ovate-lanceolate or narrower, tapering to a very long acuminate point, at length coriaceous, smooth and shining both sides; stipules small, oblong; fruiting aments often persistent, the capsules becoming rigid and polished, as in the nearly allied S. pentandra of Europe.—Banks of streams, N. Eng. to Penn., west and northward. A beautiful species on account of its showy staminate aments and large glossy leaves.
[+][+] Stamens mostly 2; capsules subsessile or very shortly pedicelled; leaves lanceolate, long-acuminate.
S. frágilis, L. (Crack Willow.) Leaves green and glabrous, pale or glaucous beneath, 3–6´ long; stipules when present half-cordate; stamens rarely 3–4; capsule long-conical, shortly pedicelled.—A tall and handsome tree, which was planted at an early day about Boston and elsewhere.—The var. decípiens, Smith, with yellowish-white or crimson twigs, buds black in winter, and smaller and brighter green leaves, ought perhaps to be excluded, the plant so named by Barratt, etc., being one of the hybrids mentioned below. (Adv. from Eu.)
S. álba, L. (White W.) Leaves ashy-gray or silky-white on both sides, except when old, 2–4´ long; stipules ovate-lanceolate, deciduous; capsules ovate-conical, sessile or nearly so.—Var. cærùlea, Koch; twigs olive; old leaves smooth, glaucous beneath, dull bluish green.—Var. vitellìna, Koch; twigs yellow or reddish; old leaves glabrous above.—A familiar tree of rapid growth, attaining a height of 50–80°. The typical form, with olive twigs and old leaves silky on both sides, is rarely found with us, but the var. vitellina is common. Pure S. fragilis is also scarce, but a host of hybrids between the two, representing S. viridis, Fries, S. Russelliana, Smith, etc., are the commonest of introduced willows. These forms are rendered almost inextricable by a further cross, by no means rare, with our native S. lucida. (Adv. from Eu.)
S. Babylónica, Tourn. (Weeping W.) Extensively planted for ornament, and in some places widely spread along river-banks and lake-shores by the drifting of detached limbs. (Adv. from Eu.)
[*][*] Leaves remotely denticulate with projecting teeth; stamens 2; capsule glabrous or silky.
4. S. longifòlia, Muhl. Leaves linear-lanceolate, 2–4´ long, tapering at each end, nearly sessile, more or less silky when young, at length smooth and green both sides; stipules small, lanceolate, deciduous; aments linear-cylindric, often clustered at the ends of the branchlets; capsule shortly pedicelled; stigmas large, sessile.—Found sparingly along the Atlantic coast from Maine to the Potomac; common westward. A shrub, rooting extensively in alluvial deposits and forming dense clumps. This species is a peculiar American type, and exceedingly variable; the earliest leaves after germination pinnately lobed.