Lamb’s Tails in the Spring Breeze
Whilst most plants are pollinated by insects, plus other invertebrates and small mammals, quite a few rely on the wind to reproduce. A common way for trees to do this is to have catkins, hazel and silver birch both being good examples with easily visible long catkins often called lambs tails, but oak, beech, hornbeam, walnut, pine and other conifers do too. Catkins are actually long slim clusters of flowers which release large amounts of small, light pollen that can be blown a long way.
Most flowers contain both male and female parts within the one flower, but wind pollinated trees usually have separate male and female flowers. These may occur on the same tree as they do in hazel or oak or sometimes on different trees for example willow and poplar. The male flowers form in clusters making the catkin, whilst the female flowers stand upright individually. Flowers of wind pollinated plants have small petals if they have any at all and catkins tend to be pale yellow, no need for bright colours, large petals or scent to attract insects when it is the wind that is doing the work! Both the male catkins and female flowers can be seen on the edges of the tree canopy where the wind will catch them, shaking the catkin, releasing the pollen and carrying it away. The female flowers then catch the pollen as it is blown past, they usually stand upright on top of twigs and often have a sticky tip or ‘stigma’ as it’s known, to catch the passing pollen. The female flowers are sometimes red, looking a little like a small sea anemone. Have a look on a hazel bush and see if you can see both the dangling catkins and also the small, red female flowers, sometimes on the same twig. Once pollinated the female flower will develop into the seed, be it an acorn, pine nut or a hazel nut.
Wind pollination works well for trees that flower early, when few insect pollinators may be about, for trees that are found in cold and windy spots too. Hazel, birch, willow and pines are trees that are early to arrive and grow on bare, rocky ground and are thought to have been amongst the trees that first colonised patches left bare by retreating glaciers after the last ice age. Wind pollination would have been an advantage in this.
Another important group of plants that are pollinated by wind are the grasses. Whilst they do not have catkins or separate male and female flowers, there are parallels to be drawn. Grass flowers tend to be green, yellow or pale brown rather than brightly coloured. They are produced at the top of a grass stem that usually stands vertical, bringing the flowers above other foliage and into the wind. They tend to be clustered, often in a spike rather like a vertical catkin and they produce a large amount of pollen which can be carried over distance. Many grasses open up when ready to release their pollen, looking like a miniature Christmas tree, so that all of the flowers will be caught in passing breezes. Some grasses do have strong colours, but this is due to the colour of the pollen not the flowers. Grasses may be at their most beautiful when releasing coloured pollen. One example of this is meadow foxtail, so named because the red pollen colours the flowering spike like a fox’s tail.
Why not have a walk around your local churchyard, chapel yard or cemetery and see if you can see any signs of wind pollination taking place.
All the best,
Harriet Carty
Diocesan Churchyard Environmental Advisor
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