Castana sativa - Sweet Chestnut

Phylum: Magnoliophyta - Class: Magnoliopsida - Order: Sapindales - Family: Betulaceae

Castana sativa - Sweet Chestnut tree

The Romans probably brought Sweet Chestnut (also known as Spanish Chestnut) trees to Britain, and in the south of England and Wales, where the climate is warm enough for self-sown seeds to germinate, these stately trees have become naturalised in the wild; elsewhere they are planted in parks a nd large gardens for their ornamental value rather more than for the fruits, which are popular at Christmastime.

The wood from Chestnut trees is still sometimes used for fencing, mainly on smallholdings, and coppiced Chestnut shoots are a traditional source of poles for hop growing.

Bark of a mature Sweet Chestnut tree

In wintertime it is not at all easy to distinguish a young Sweet Chestnut from many of the other saplings and young trees in mixed woodland (even though the fallen leaves are slow to decay and are quite distinctive... but which tree did they fall from?), because the bark has no obvious discriminating features until the tree is at least twenty years old, when the first surface fissures begin to appear.

There is no such problem with mature Sweet Chestnut trees, however; the bark is extremely fibrous and splits in a spiral pattern around the trunk of the tree.

Ancient Sweet Chestnut trees have huge trunks with deep fissures. Their branches spread widely and sometimes descend almost to ground level, providing wonderful shelter for animals and for people during heavy rainstorms.

Leaves of the Sweet Chestnut tree

Leaves of the Sweet Chestnut

Flowers of the Sweet Chestnut tree

Male and female flowers

Seed cases of the Sweet Chestnut tree

Prickly seed cases

Fruits of the Sweet Chestnut tree

Sweet Chestnut fruits

Long (male) catkins appear in early summer, and later the fruits develop from the female flowers.

The nuts, which are protected inside spiny bracts, ripen in late autumn and are at their best in December. (Roast chestnuts are traditionally associated with log fires and turkey stuffing at Christmastime.)

Fungi associated with Sweet Chestnut trees

Although the Sweet Chestnut is reported to be an ectomycorrhizal tree, few of the associated fungi from its native lands seem to have opted to join it in Britain and Ireland. There are, however, plenty of leaf-litter mushrooms to be seen under Sweet Chestnuts as well as a few bracket fungi that seem to be particularly partial to its bark and timber.

Fistulina hepatica

One of the bracket fungi commonly seen on Sweet Chestnuts (although they are even more frequent on oaks), mainly on standing trees but also occasionally on fallen trunks, is the Beefsteak Fungus, Fistulina hepatica (left). This striking bracket fungus feeds on the dead heartwood, and so perhaps strictly it should be classed as saprophytic rather than parasitic.