The foreground of this picture near the grotto, are a group of Dawn Redwoods and in the background a group of their close relatives, the Swamp Cypresses. They can be told apart by their foliage. In the former the leaves and needles are opposite each other and in the latter they alternate. More bizarrely the Dawn Redwood, unlike virtually every other tree in existence, has its buds below the leaf and not between the leaf and the stem. This gives the stem a very odd look indeed. As if that were not enough the Swamp Cypress was introduced into Britain in 1640 and the Dawn Redwood amazingly was only discovered in 1941, and only named in 1948. Consequently we know our Swamp cypresses will eventually lose their neat conical shape and develop buttresses, but there is little idea what the Dawn Redwoods will do.
The Swamp Cypresses grow out of water in swamps from Florida to Delaware and along the banks of the Mississippi and Missouri rivers. It is often seen in films covered in Spanish moss. In 1941 both the fossil and living Dawn Redwoods were found independently. A small group of trees was discovered half way up the River Yangtse in the Szechuan province of China. The foliage was being fed to cattle locally. The discovery caused a botanical sensation and due to the ease with which it can be reproduced by cutting, and the tree is now found everywhere. In the spring it is the first of the two to come into leaf and they both colour well in the autumn.
The Swamp Cypress was named before other redwoods were even discovered and at the time incorrectly called a cypress. In actual fact they are both redwoods. More confusingly the timber is called cypress whereas the timber of real cypresses is called white cedar. It is all very odd. To complete this mix up the Swamp Cypress produces pneumatophores, or “knees”, rather like mangroves. These are a kind of aerial root that grow up out of the stagnant water where the tree usually lives and were believed to take in oxygen. It is now thought they do no such thing. Nobody seems to know what these structures, which look like ant hills, do. They can be seen in specimens in Bushy Park, growing up by the water’s edge in the Waterhouse Plantation. There are further examples of the Dawn Redwood and Swamp Cypress at the eastern corner of the Ladies Pond.