Salix viminalis L. Osier Hemp Willow. Shrub or small tree to about 10m (33ft), native to central and western Europe (including Britain). Often coppiced and used in making baskets and fences. Catkins open in April and May before the leaves unfold, males grey and silky with yellow anthers, about 1.8cm (¾in) long, females green, releasing seeds in June. Leaves are narrow with inrolled margins, dark green above and covered with silky hairs underneath. Z4.