Salicaceae

Deciduous perennial trees or shrubs, individual plants either bearing pollen-producing (male) or seed-producing (female) flowers but not both: Poplars and Willows.

Flowers are unisexual and arranged in catkins consisting of many small flowers closely packed together and attached to and obscuring a narrow central stalk, each flower supported by a small bract or scale at its base, both sepals and petals absent. Most male plants in this family bear silver tufts of soft protective hairs resembling pussywillows and these are flowers that are not yet fully opened or developed. Usually flowering in early spring, often before the leaves appear. Poplar catkins are drooping and their scales are often toothed, lobed or hairy; Willow catkins are mostly ascending or spreading, seldom drooping, and their scales usually do not have prominent teeth or lobes. Each flower may have 1 or 2 large glands at its base (Willows) or be set on an oblique cup-shaped disk (Poplars). Flowers in Willows have an odour and their sepals are modified into nectar-producing structures. Stamens 2 to 80 (seldom 1, resulting from fusion of 2 stamens). Carpels and stigmas 2 to 4, the stigmas sometimes cleft into 2 equal parts. Bud scales one to several. Fruit are capsules with 2 to 4 valves and bearing many tiny seeds covered in long white hairs.

Most with simple alternate leaves that are spiral or two-ranked and toothed, the vein expanding at the point of the tooth and associated with spherical glandular bristles. Stipules usually present but are often deciduous.

Plants usually contain tannins and often also salicin, an aspirin-like chemical that is well known to reduce fever, pain and inflammation.