September 05, 2010

This week in wildlife

Apart from the rusty horse chestnuts, most of the city's trees are still green - but the acer in my garden tells a different story. Each day there is a little less light, and soon there won't be enough for photosynthesis to take place. So it's starting to get ready for winter, when it will become dormant, by stopping cholorphyll production so that the existing stores in the leaves simply break down, leaving the oranges and purples of anthocyanins and, in the maple family, glucose left over from photosynthesis, which gives the leaves their red tint. Soon they will start growing a little plug of cork at the leaf axil so that when they drop, the twig is not damaged; and before long the trees will be bare black skeletons again, and for months it will be hard to imagine them threshed and castled in green.