NATURE NOTE

Ivy, being evergreen, is a symbol of everlasting life - the reason, no doubt, why the plant is inseparably entwined with Christmas. Yet, with its creeping habit and poisonous leaves, it seems a rather sinister and mysterious form of decoration. It can certainly be toxic if eaten in large quantities, and one hears of horses killed by it. Yet deer browse on it with relish, especially in cold weather. It is often fatal to trees - but not because (as some suppose) it drains away their life-blood. Like most plants, it gets nutrients through its roots, and when it grows up a trunk, with hundreds of suckers clinging to the bark, it is merely using the tree as a convenient support. Danger comes from the fact that its dense mass of leaves greatly increases what foresters call the tree's sail area, raising wind resistance to such a degree that host and parasite are liable to be blown over together. Yet ivy has its uses: its foliage offers good habitat to small birds, harbouring thousands of insects for them to eat, and its berries make excellent food at this time of year, when other kinds of wild provender run short.

Duff Hart-Davis