- Name also: Laurel Willow (USA)
- Family: Willow Family – Salicaceae
- Growing form and height: Shrub or tree. 2–14 m (7–45 ft.).
- Flower: Male and female flowers on separate plants. Inflorescence a hairy, nodding catkin. Individual flowers in axils of catkin scales, small, lacking perianth. Catkin scales yellowish-white, soon falling. Stamens usu. 5, filaments white-hairy. Pistil formed from 2 fused carpels. Dried female catkins persist over the winter.
- Leaves: Alternate. Short-stalked, stipulate. Stipules small, soon falling. Blade 6–8 cm (2.4–3.2 in.) long, elliptic, short-tapered, finely glandular-serrate, hairless, glossy above, pale beneath, vein pairs 10–12.
- Buds: Hairless, glossy, brown.
- Fruit: Two-valved, hairless capsule containing many slender, sharp-pointed, plumed seeds.
- Habitat: Shores, damp broadleaf woods, rich swamps, wet meadow dykes. Rarely an ornamental.
- Flowering time: June. Flowers when already leafy.
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.
Bay willow is a fairly demanding tall shrub or small tree. It has hairless, glossy branches, and flowers when the leaves are almost fully grown.
Willows are a group of 400 to 500 woody species. They occur in all continents apart from Antarctica. Willows so closely resemble poplars (Populus) that they are thought to be descended from similar ancestors. Those willows which have several stamens, such as bay willow, occurred already in the Tertiary, and are most similar to 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. 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.