Species of the month: October

Species: Horse-chestnut tree

In October our countryside is transformed by the golden colours of autumn.  One of our most distinctive broad leaf trees at this time of year is the horse-chestnut, popular with children for its crop of shiny brown conkers.

Surprisingly the tree is not a native, but introduced here from northern Greece in the 1700's. Our other chestnut tree is the sweet chestnut, thought to have been introduced by the Romans. This has smaller brown seeds, popular at Christmas, encased in a green shell with much finer spikes than a conker shell.

Although eaten by deer, conkers are not good for horses, but they will eat small quantities.  It is possible however, that the name refers to an ancient use of conkers to control the build up of gas in their stomachs.

Alternatively, the name may come from the horse shoe shaped leaf scars which are visible at the bases of branches in winter. These buds grow leaves which are divided into five to seven long oval shaped leaflets.

Since 2002, horse-chestnuts in the south east have been suffering from infestations by a leaf miner, with noticeable brown blotches appearing on the leaves before they turn brown in the autumn.  The leaf miner is the larvae of a moth (Cameraria ohridella).  The species is likely to have spread across Europe due to accidental transport by man.  At present, it is uncertain whether the larvae on its own causes the blotches or how much damage this infestation causes the tree.

What else to look out for in October

This is a good month to see common seals hauled up on the shore at certain locations around the Kent coast.