Salix alba is a tree to 25 m tall; fibrous rooted; branching low, flexible, not especially brittle at base, twigs erect or spreading, silky hairy, dull yellow-greenish to brown, stipules minute, soon deciduous.
Leaves alternate, stalk 0.3-0.6 cm, silky-hairy (leaf stalks of young shoots glandular at tip), blade narrowly lance-shaped, tip long-pointed, white-hairy above and below, 4-10 cm long, 1-2.5 cm wide, waxy white below, teeth glandular, 7-10 per cm of margin; leaves expand early May; winter plant leafless 140 days (Britton 1874).
Flowers of males and females on separate trees (dioecious), expanding with leaves, catkins 3-6 cm on a stalk 1-4 cm with 2-4 small leaves, males pussy-willow-like, mostly insect pollinated, some wind pollination.
Fruit a capsule, 0.3-0.5 cm, hairless, seeds hairy, wind dispersed, germinate within 24 hours on moist soil. Very fast growing.
Wetland status: FACW.
Frequency in NYC: Infrequent.
Origin: Europe to Central Asia.
Habitat: moist to wet soil.
Notes: See S. nigra for diseases and predators. A host tree of the Asian longhorn beetle, Anoplophora glabripennis (see Norway maple).