Leaves: stipules foliaceous, apex rounded; petiole (1-)4-15 mm, with pairs or clusters of spherical glands distally; largest medial blade amphistomatous, lorate, very narrowly elliptic, narrowly elliptic, or narrowly lanceolate to lanceolate, base convex, abaxial surface not glaucous, pilose, hairs white and ferruginous, straight or curved, (secondary veins protruding abaxially, impressed adaxially). Catkins: staminate (stout), 24-50 × 8-15 mm, flowering branchlet 3-27 mm; pistillate moderately densely flowered, slender or stout, 30-63(-70 in fruit) × 9-15 mm, flowering branchlet 10-30 mm; floral bract 2.8-4 mm. Staminate flowers: abaxial nectary (0-)0.4-0.8 mm, adaxial nectary 0.3-0.6 mm, nectaries often distinct, sometimes connate and shallowly cup-shaped. Pistillate flowers: (abaxial nectary rarely present, then nectaries distinct or connate and shallowly cup-shaped), adaxial nectary 0.2-0.5 mm; stipe 0.8-4 mm; ovules 28-30 per ovary; styles 0.2-0.6 mm. 2n = 76. Flowering late May-late Jun. Riparian thickets, openings in woods, silty, sandy to gravelly alluvium, along streams, wet meadows, lakeshores; 30-3100 m; Alta., B.C., N.W.T., Sask., Yukon; Alaska, Calif., Colo., Idaho, Mont., Nev., Oreg., S.Dak., Utah, Wash., Wyo.