Shrubs or trees, 1-5(-17) m. Stems: branches gray-brown or red-brown, glabrous or hairy; branchlets yellow-brown or red-brown, pubescent or densely long-silky-villous, hairs spreading, appressed. Leaves: stipules rudimentary on early ones, foliaceous or rudimentary on late ones; petiole puberulent, villous, or short-silky adaxially; largest medial blade (sometimes hypostomatous) linear, 39-96 × 5.3-14 mm, 6.5-31 times as long as wide, abaxial surface glabrous or densely silky-villous to glabrescent, hairs appressed or spreading, straight, adaxial sparsely to very densely long-silky-villous; juvenile blade densely silky-villous abaxially (hairs relatively long, spreading, appressed). Catkins: staminate 7-42 × 4-9 mm, flowering branchlet 2-56 mm; pistillate densely or moderately densely flowered, slender to stout, 22-43 × 3-11 mm, flowering branchlet 2-55 mm; floral bract 1.4-2.6 mm, apex acute or convex, entire or erose, abaxially hairy throughout or proximally, hairs wavy, straight, or crinkled. Staminate flowers: abaxial nectary 0.5-0.9 mm, adaxial nectary narrowly oblong, square, or ovate, 0.4-1.1 mm; anthers 0.6-1.1 mm. Pistillate flowers: adaxial nectary oblong, ovate, or flask-shaped, 0.4-1.3 mm, longer than stipe; stipe 0-0.2 mm; ovary pyriform, pilose or villous to glabrescent, beak abruptly tapering to styles; ovules 12-24 per ovary; styles (± distinct) 0.2-0.5 mm; stigmas flat, abaxially non-papillate with pointed tip, or slenderly cylindrical, 0.3-1 mm. Flowering mid Apr-mid May. Riparian, sandy-gravel floodplains; 0-600 m; Calif., Oreg. Variety hindsiana often is not distinguished from var. exigua. The two are difficult to separate morphologically even though var. hindsiana has been shown to have highly diverged chloroplast DNA (S. J. Brunsfeld et al. 1992). It can be distinguished from var. exigua by its soft, spreading hairs on branchlets and juvenile leaves (S. Brunsfeld, pers. comm.).

Hybrids:

Variety hindsiana forms natural hybrids with var. exigua.