A bushy shrub, 10 to 12 ft high, occasionally taller; young shoots and buds more or less downy. Leaves extremely variable in outline (roundish, elliptic, ovate, obovate or oblanceolate), shortly acute or acuminate at the apex, rounded or tapered at the base, toothed, 11⁄2 to 4 in. long, 1⁄2 to 2 in. wide, upper surface dull, dark green at maturity, underside covered with a thin waxy bloom which disappears towards the apex of the blade, persistently downy, at least on the veins; stalk 1⁄4 to 3⁄4 in. long. Catkins appearing with the leaves, shortly stalked; scales hairy, dark at the tip. Male catkins 3⁄4 to 11⁄4 in. long, 3⁄8 to 1⁄2 in. wide; stamens about twice as long as the scales, hairy towards the base. Female catkins up to 2 or 3 in. long in fruit; ovary distinctly stalked, usually glabrous, style about one quarter as long as the ovary or slightly longer, the stigmas divided, almost as long as the style.
Native of northern and central Europe, Siberia, etc., occurring in Britain from Yorkshire and Lancashire northwards, and in northern Ireland. It has been represented in gardens at different times by an extraordinary number of forms, varying in the shape and size of their leaves. Many of these are figured by Forbes in the Salictum Woburnense, but have little interest. The species is indeed one of the dullest and most uninteresting of hardy shrubs, and is not worth a place in the garden proper. It is seen in the seedling state oftener than most willows are. Some botanists have considered that S. nigricans and S. phylicifolia are not specifically distinct from each other. However, S. nigricans can usually be distinguished by its thinner, larger, duller green, more downy leaves, which, at least the younger ones, turn black on drying, and by the waxy bloom on the lower part of the underside.
S. × tetrapla Walker ex Sm. S. nigricans × S. phylicifolia – A rather common natural hybrid between these two related species, and combining their characters in so many different ways that definition is impossible. Many of its forms have been described as species.
S. mielichoferi Sauter S. glabra var. mielichoferi (Sauter) Anderss. – Allied to S. nigricans, but more bushy, with thicker branchlets swollen at the nodes. Leaves green beneath, not blackening when dry. It could be confused with S. glabra, but in that species the leaves are very lustrous above and the undersides are coated throughout with a waxy bloom.