Plants 1.2-4 m, (sometimes forming clones by stem fragmentation). Stems: branches (sometimes highly brittle at base), yellow-brown or red-brown, not to sometimes strongly glaucous, (dull to slightly glossy), glabrous or puberulent at nodes; branchlets yellow-brown to red-brown, (weakly or strongly glaucous or not), puberulent, (buds alba-type or intermediate, scale inner membranaceous layer free, not separating from outer layer). Leaves: stipules absent or rudimentary on early ones, foliaceous on late ones, apex acute; petiole convex to flat adaxially, 5-16 mm, tomentose or velvety adaxially; largest medial blade (sometimes amphistomatous), lorate or very narrowly to narrowly elliptic, 44-110 × 6-22 mm, 3.4-9.9(-12) times as long as wide, base convex or cuneate, margins flat to slightly revolute, entire or shallowly serrulate, apex acuminate to acute, abaxial surface glaucous, sparsely short- or long-silky to glabrescent, hairs (white, also ferruginous), straight or wavy, adaxial slightly glossy, sparsely short-silky, (hairs also ferruginous); proximal blade margins entire or shallowly serrulate; juvenile blade reddish or yellowish green, densely long-silky abaxially, hairs white and ferruginous. Catkins flowering just before or, sometimes, as leaves emerge; staminate stout, (1.4-2.7-)16-28 × 9-17 mm, flowering branchlet 1-3 mm; pistillate loosely flowered, stout, (1.5-2.7-)19-44(-65 in fruit) × 10-18 mm, flowering branchlet 1-6 mm; floral bract brown or bicolor, 1.1-2.4 mm, apex rounded or convex, abaxially hairy, hairs straight. Staminate flowers: adaxial nectary narrowly oblong, oblong, or ovate, 0.3-0.9 mm; filaments distinct or connate less than 1/2 their lengths, glabrous or hairy on proximal 1/2 or basally; anthers yellow, ellipsoid, shortly cylindrical, or globose, 0.5-0.9 mm. Pistillate flowers: adaxial nectary oblong, narrowly oblong, or ovate, 0.4-1 mm; stipe 1.1-2.1 mm; ovary pyriform, beak sometimes slightly bulged below styles; ovules 12 per ovary; styles 0.3-1 mm; stigmas flat, abaxially non-papillate with rounded or pointed tip, 0.2-0.3-0.48 mm. Capsules 5-7 mm. 2n = 76. Flowering early Mar-late Jun. Streams, lakeshores, wet meadows, springs, old burns in subalpine conifer forests, sandy, granite substrates; 1400-3500 m; B.C.; Calif., Idaho, Mont., Nev., Oreg., Wyo. See 85. Salix drummondiana for comments on differences.
Salix lemmonii forms natural hybrids with S. geyeriana.