- Family: Willow Family – Salicaceae
- Growing form and height: Tall shrub or tree. 3–10(–15) m (10–35(–50) ft.).
- Flower: Male and female flowers on separate plants. Inflorescence a catkin on a short, leaved stalk. Individual flowers in axils of catkin scales, small, lacking perianth. Catkin scales elliptic, dark-coloured, and hairy. Stamens 2, filaments long, with hairy base, anthers yellow and hairless. Pistil formed from 2 fused carpels, ovary long-stalked, hairy.
- Leaves: Alternate. Fairly long-stalked, stipulate. Stipules large, kidney-shaped, toothed, sparsely pubescent, soon falling. Leaf-blade 6–10 cm (2.4–4 in.) long, elliptic or ovate to obovate, often with bent tip, thick, with entire or winding to sparsely toothed margin, dark green and sparsely hairy to hairless above, grey and densely short-hairy beneath. Vein pairs 6–8(–10).
- Buds: Yellowish-brown, hairy or hairless.
- Fruit: A fairly slender, short-hairy capsule. Seeds plumed.
- Habitat: Damp and rich coniferous forests, broadleaf woods, shores, swamps with thin peat layer, roadsides, field margins, ditches.
- Flowering time: April–May.
The willows are insect-pollinated, sympodially growing, dioecious trees, shrubs, or dwarf shrubs. Their buds have a single protective scale, and their leaves are entire and stipulate. The inflorescence is a catkin which falls off in one piece. Hybrids between willow species are common.
The goat willow, also known as great sallow or “pussy willow”, is a much-branched, dense tree or tall shrub that flowers before coming into leaf. It often occurs as scattered, solitary individuals in damp, rich woods. Its twigs are stout, quite fragile, hairless, and yellowish-brown or grey. A tree-size goat willow has fissured, thick bark.
The willows are a group of 400 to 500 woody species. They occur in all continents apart from Australia and Antarctica. The willows so closely resemble the poplars (Populus spp.) that they are thought to be descended from similar ancestors. Those willows which have several stamens, such as the bay willow (S. pentandra), occurred already in the Tertiary, and are most similar to the poplars. The more highly evolved willow species which have only two stamens seem to have increased only after the ice age. Most of the Finnish species belong to this group. The willows are of economic importance e.g. as raw material in basketry and as a source of tannins. In addition, the bark yields salicine, a medicinal substance.