Stems: branches short-silky or villous to glabrescent; branchlets usually moderately densely long-silky, villous, or woolly. Leaves: petiole (0.5-)1-3(-4) mm; largest medial blade narrowly oblong, oblong, narrowly elliptic, elliptic, narrowly oblanceolate, or obovate, (10-)23-30(-40) × 5-16 mm, (1.5-)2.8-3(-4) times as long as wide, base rounded, convex, or subcordate, apex acute or convex, abaxial surface moderately densely villous or long-silky, adaxial pilose, villous, or long-silky to glabrescent, hairs straight or wavy. Catkins: staminate 5.3-21 × 4-10 mm, flowering branchlet 0.3-10 mm; pistillate globose, subglobose, or stout, 6-20 × 4-15 mm, flowering branchlet 0.3-11 mm; floral bract tawny, 1-3 mm. Staminate flowers: abaxial nectary 0.5-1.1 mm, adaxial nectary 0.5-1.4 mm; filaments distinct or connate less than 1/2 their lengths, glabrous, or hairy on proximal 1/2; anthers ellipsoid or globose, 0.3-0.5 mm. Pistillate flowers: abaxial nectary (0-)0.4-1.4 mm, adaxial nectary oblong, 0.8-2 mm; stipe 0-0.6 mm; ovules 2-5 per ovary; styles connate to distinct 1/2 their lengths, 0.5-1.5 mm. Capsules 3-6 mm. 2n = 38. Flowering mid Jun-late Aug. Moist to mesic open forests, sedge fens, seepage on limestone, scree slopes, gravel floodplains; 0-4000 m; Alta., B.C., Man., N.W.T., Nunavut, Ont., Que., Sask., Yukon; Calif., Colo., Idaho, Mont., N.Mex., Oreg., Utah, Wash., Wyo. Variety brachycarpa occurs in Nunavut only on islands in James Bay.

Hybrids:

Variety brachycarpa forms natural hybrids with Salix arizonica, S. barclayi, S. boothii, S. candida, S. chlorolepis, S. glauca var. villosa, and S. planifolia.

Placement of specimens from Anticosti Island, Quebec, and North Point, James Bay, Ontario, with densely villous branchlets and relatively short petioles, thought to be hybrids with Salix glauca var. cordifolia, is dubious.

Variety brachycarpa × Salix candida (S. ×argusii B. Boivin) is infrequent in Manitoba, Quebec, and Saskatchewan.

Variety brachycarpa × Salix chlorolepis (S. ×gaspeensis C. K. Schneider) resembles var. brachycarpa but has leaves only slightly pilose and ovaries with hairs only on the beaks (G. W. Argus 1965).

Variety brachycarpa × Salix glauca var. villosa (S. ×wyomingensis Rydberg) is a frequent hybrid in southern Rocky Mountains. It is characterized by stipes 0.3 mm or longer, long-cylindrical catkins, ovaries with relatively long beaks, petioles more than three times the length of buds, and leaves sparsely hairy. The extent and nature of this hybridization needs to be studied (G. W. Argus 1965).

Variety brachycarpa × Salix planifolia 'var. monica' occurs in Steens Mountains, Oregon.