Complete Guide to Catkins

In late winter and spring, usually before the leaves appear, catkins hang from the bare branches of trees like alder, hazel and silver birch. The first known use of the word ‘catkin’ is in an English translation of a Flemish botanical guide written in 1554 by physician and botanist Rembert Dodoens. He uses the Dutch word katteken meaning ‘little cat’ which was translated as ‘catkin’. Catkins are also known as ‘aments’, derived from the Latin for ‘strap’ or ‘string’.

Catkins are slim clusters of flowers without petals. In most cases, all of the flowers in a single catkin are either male or female. Some species, such as oak, have both male and female single-sex catkins on the same tree (monoecious), whereas others, like poplar, bear male and female catkins on separate trees (dioecious). Other species have only male catkins, such as hazel and oak whose female flowers are smaller and less conspicuous. The sweet chestnut is unusual in producing both male catkins and bisexual catkins which have female flowers at the base.

Pollen-rich male flowers are often produced in pendulous clusters – like the fuzzy yellow hazel catkins that appear around mid-February. Most catkin-producing trees are wind-pollinated. The hanging catkins enable tiny grains of pollen to be picked up and carried by the wind. An exception to this is willow, which has evolved to be primarily insect-pollinated.

The best time of year to look for catkins is in late winter and early spring before the deciduous canopy appears. Trees produce catkins at this time of year because their leaves have not yet developed, so wind-borne pollen is not impeded by foliage and the tiny grains are more likely to make contact