Sand dune willow is a 1-3m tall shrub with unisexual flowers. Its staminate catkins (aka aments) have 2 filaments and develop on branchlets with green, densely silky bracts, anthers are yellow, pistillate catkins have glabrous ovaries and styles usually greater than 0.5mm. The pistillate bracts are narrowly ovate. Fruits are lanceolate, smooth, and 5-8mm. Its leaves are alternate, lance-ovate to broadly ovate, 4-8cm long by 1.5-4cm wide, abruptly tapering to a sharp point, the margins are concave at the tip, glandular-serrate, rounded or cordate at the base, green on both sides, and strongly nerved beneath. Its vegetative parts may be covered with fine hair, stipules are 6-15mm, petioles are 4-8mm and somewhat clasping. It brown scales are covered with dense, shaggy hair.
This genus is notoriously difficult to distinguish to the specific level when not in flower. Salix cordata has leaves that are green beneath, usually permanently wooly, and pedicels 0.5-1mm, which are distinguish it from other species.
