Populus alba

White poplar or silver poplar is in the willow or Salicaceae family and is most closely related to the aspens. It is native to Morocco through central Europe (north to Germany and Poland) to central Asia. It was introduced into North America in the mid-1700s and has spread prolifically over most of the continent.

• Leaves are alternate, simple, 4–12 cm long, coarsely toothed on older trees but five-lobed on younger, fast growing trees; white down is found on both sides of the leaf, but this layer wears off the upper side, not the lower, which stays white until autumn leaf fall. Small branches and buds also have white down.
• Flowers are catkins up to 8 cm long, produced in early spring; they are dioecious (male and female catkins on separate trees); the male catkins are grey with conspicuous dark red stamens, the female catkins are greyish-green.
• Bark has characteristic diamond-shaped dark marks on young trees, becoming blackish and fissured at the base of old trees.
• White poplar hybridises naturally with the closely related common aspen (P. tremula), the resulting hybrid being grey poplar (Populus × canescens).