With harvest season upon us, it got me thinking about all things seeds. From a tiny acorn, a giant oak may grow. However magical it may seem, we all know that every beautiful old tree began life as a tiny seed. But if seeds were to fall straight off the tree and germinate at the roots of the parent, the next generation would fail and trees would be in crisis. Evolution created the answer to this conundrum and trees have developed a range of amazing techniques to ensure their seeds travel far and wide…
The Animal Store Cupboard
Seeds make a tasty treat and an essential food source for many animals. The bounty of seeds produced in the autumn months make a valuable resource for animals, which they cache and use to survive through the cold winter months. Squirrels and jays gather, carry away and then bury lots of acorns and chestnuts. Not all of these food stashes will be retrieved during the winter and the remaining ones are handily already planted in the soil, ready to germinate in the spring.
Cadging a Ride
Some trees prefer to use animals in quite a different way. Anyone with a dog will know that some plant seeds have an incredible ability to stick to animals’ coats. These seeds, like that of the sweet chestnut, have a casing that is covered with hooks and spines, perfectly designed to attach to any passing mammal. Cadging a ride on the side of a dog, fox, badger or mouse is a sure way of making it across the forest floor with little effort.
Riding the Wind
The British autumn is well known for its changeable weather, and every year this includes several days of high winds. The wind is used as one of the most favoured methods of seed dispersal for trees, from the tiny silver birch seeds that spread in their millions to the iconic winged sycamore seed that helicopter and spiral as they travel through the air.
Trees that often grow next to water take full advantage of the flowing water in rivers and streams. Many species of willow, including the goat willow, have light seeds that are capable of floating downstream without suffering damage, ready to be deposited in their new home.
Some of the most remarkable plants do not rely on the elements or animals to spread their seed. Instead, they like to take matters into their own hands, using their own force to eject the seeds. Many such plants allow water to evaporate from within their seed pods, building up the pressure. Stand near to a gorse bush in the summer and you may hear the seed pods popping in the heat.
So while you are out walking in woodland this autumn, have a good look around and see if you can spot seeds on their travels.
21 September 2016