Writing around 300 BC, the Greek botanical writer, Theophrastus, declared, "The oak bears more things beside its fruit than any other tree." He noticed several different types of gall - a small growth formed when a female wasp lays an egg in the central vein of a growing leaf. The newly hatched larvae secrete a chemical which causes the leaves to mutate, forming the galls - protective homes for the growing insects. The largest are pinkish-white "oak apples", which can grow as big as golf balls. There are also smaller currant-galls, marble-galls, and spangle-galls.

The oak supports at least 350 varieties of insect - more than any other tree. Those living in the bark attract birds, such as great-spotted woodpeckers, to feed. Caterpillars of moths and butterflies eat the leaves. Most damaging is the Oak Leaf-Roller Moth, whose grub rolls over a leaf so that it can pupate within it. In some years, there are so many caterpillars that they can strip every leaf from the tree. Yet the sturdy oak usually survives, with only a small decrease in its annual growth.

Through the seasons

From July to August, the canopy of oak trees in southern England hosts colonies of the rare Purple Emperor Butterfly, a spectacular creature whose colourful wings can have a span of 84mm. Here the butterflies live on a diet of sticky honeydew, secreted by aphids on the oak leaves. Find out more about the purple emperor here

The acorns which fall to the ground in autumn provide another important food source, for wood pigeons, rooks, squirrels and mice. These birds and small mammals in turn attract birds of prey, including buzzards, sparrowhawks and owls, which hunt in the forest.

In the past, acorns were a vital foodstuff for people's pigs, turned loose in the forest every November. The right to feed pigs on the acorns is still held by the inhabitants of the New Forest.

An ancient oak often has a hollow trunk, its centre eaten away by fungi such as the "Poor Man's Beefteak". The hollow provides a roosting place for owls in daytime, and a home for colonies of bats, which hibernate there in the winter, protected from the cold.

After its death, an oak tree continues to support life. More than 200 varieties of fungi live on the decaying wood, which is also eaten by woodlice and other insects. They break down the oak tree's nutrients, which return to the earth, to feed new oak trees.