CATKIN ID GUIDE

Catkins are male or female flower clusters on certain broadleaved trees. Catkin shapes and flowering times vary widely between tree species. Pollen is transferred from male to female flowers by the wind or by insects, setting the seed or nut. The seed develops within female catkins, holding the seeds until ripe and aiding dispersal.

Silver birch: This frequent, graceful tree flowers April–May. Male catkins are long, drooping and yellow-brown; female catkins are smaller and pale green. The seeds are released in autumn.

Aspen: Occasional in heathland and woodland. Flowers February–April. Male catkins are pink-red with grey down-like hairy caterpillars; female catkins are greenish-grey. Fruiting catkins in May are white and woolly.

Alder: Common by rivers and in wet woodland. Flowers February–March. Male catkins are long, purple at first, greener when ripe. Female flowers branching, club-shaped. Small dark alder ‘cones’ release seeds in autumn.

Black poplar: An uncommon species found in wet woods and hedges. Flowers in March. Male catkins have dark red anthers; female catkins are larger, green and stubby. Fruiting catkins in June are white and woolly.

Hazel: Common shrub in woods and hedges. Flowers Feb–March. Pale yellow, long male catkins are like lamb’s tails. Female flowers are tiny, red, protruding from twig buds that become hazelnuts in autumn.

Goat willow: A broad-leaved willow common on wet soils. Flowers March– April. Male catkins are stubby with yellow pollen (‘pussy willow’); female catkins are longer, green. Fruiting catkins release fluffy seeds in June.

Hornbeam: Common in south and east England. Flowers April–May. Drooping male catkins are green with open bracts; female catkins have longer bracts, with winged fruits released in autumn.