Sp. Pl. 2: 1017. 1753.
Plants sometimes forming clones by stem fragmentation. Stems: branches (sometimes ± brittle at base), yellow-brown or olive-brown, not or weakly glaucous, glabrous; branchlets yellow-brown or olive-brown, violet tinged, glabrous. Leaves (sometimes opposite or subopposite); stipules absent; petiole shallowly grooved adaxially, 2–7 mm, glabrous adaxially; largest medial blade lorate, narrowly oblong, narrowly oblanceolate, oblanceolate, 35–77 × 5–20 mm, base convex or rounded, margins strongly revolute, entire or serrulate, apex acute, acuminate, or convex, abaxial surface glaucous, glabrous, adaxial dull to sublustrous, glabrous; proximal blade margins entire; juvenile blade yellowish green or reddish, glabrous or sparsely pubescent abaxially, hairs white, sometimes also ferruginous. Catkins flowering before leaves emerge, (subopposite, recurved); staminate stout or subglobose, 25–33 × 6–10 mm, flowering branchlet 0 mm; pistillate densely flowered, slender or stout, 13.5–34.5(–35 in fruit) × 3–7 mm, flowering branchlet 0.5–3 mm; floral bract black or bicolor, 0.8–1.6 mm, apex rounded, abaxially hairy, hairs straight or wavy. Staminate flowers: adaxial nectary oblong, square, or ovate, 0.4–0.8 mm; filaments connate; anthers (distinct), purple turning yellow, ellipsoid or globose, 0.4–0.5 mm. Pistillate flowers: adaxial nectary ovate, 0.3–0.7 mm; ovary obturbinate, beak gradually tapering to styles; ovules 6 per ovary; styles 0.2–0.3 mm. Capsules 2.5–5 mm. 2n = 38.
Phenology: Flowering mid Mar-mid May.
Habitat: Floodplains and shores, fens, swamps, alder thickets, sandy and limestone beaches, low dunes
Elevation: 0-900 m
Introduced; N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Calif., Conn., Del., D.C., Ga., Ill., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Mo., N.H., N.Y., N.C., Ohio, Oreg., Pa., R.I., Utah, Vt., Va., W.Va., Wis., Europe.
Salix purpurea occurrence in Ohio is based on information from T. S. Cooperrider (pers. comm.).