Castanea sativa

The Romans introduced this remarkable Italian tree to Britain during their long spell of dominion and colonisation, from a.d.42 to a.d.410: their object was to raise the familiar nuts which were, in Italy, a staple food for their legionaries. But the British climate does not encourage a good chestnut harvest, and nearly all the nuts we eat today are imported. In the south of England, the chestnut ripens fertile seeds, and it has sprung up here and there in the woods, ever since Roman times. From the Midlands northwards. chestnut is only seen as an ornamental specimen tree, artificially sown and planted.

In winter, chestnut is fairly easily known by its stout twigs, which are rather angular and marked by ridges; the winter buds are large and plump, and pinkish brown in colour. In summer the very large long-oval leaf makes recognition easy; leaves are often 23cm long by 5cm broad, and glossy green above; their veins are distinct, and each side-vein ends in a sharp tooth. Chestnut bark is boldy marked by a network of ribs, taking up a spiral pattern with advancing age.

Chestnut catkins do not open until July. They are remarkable in some of them having both male and female flowers on the same

Castanea Sativa Bonsai

figure is

Winter twig of Sweet chestnut (life size); winter bud (x6).

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Winter twig of Sweet chestnut (life size); winter bud (x6).

stalk, and also in being pollinated by insects, rather than by wind. Each catkin stalk, which is often 12cm long and looks rather like a hairy caterpillar, carries numerous male flowers, bunched in groups of seven. Each male flower consists of six green petals and about a dozen stamens, with conspicuous golden anthers. Once the pollen has been shed the wholly male catkins fade and fall: the male part of a mixed catkin, however, remains attached to the base, until the fruit has ripened, and then falls with that. Female flowers appear near the base of smaller spreading or upcurved catkins, in litde groups that look like leafy buds; they are surrounded by green bracts which form a cupule. Usually there are three flowers in each cupule. and each is tipped with a tuft of styles. The male flowers beyond open, if at all well after those in the big fully male catkins. Chestnuts ripen rapidly, and in September, 2 months after flowering, each flower-group has changed into a fruit-group holding from one to three single-seeded nuts, the familiar chestnuts. By this time, too, the bracts forming the cupule have expanded to form a tough husk, bearing many sharp greenish-yellow spines on the outer surfaces of distinct lobes, usually four in number.

FIGURE 29

Fruiting branch of Sweet chestnut in October. Each spiny husk consists of a group of four bracts, enclosing up to three single-seeded fruits - the chestnuts [xj).

Sweet chestnut is easily raised from seed, provided the nuts are carefully stored and not allowed to get too dry or become mouldy; moist sand is a good storage medium. Chestnut timber is very strong and Its heartwood is naturally durable; it resembles oak but lacks that tree's decorative 'silver grain.' Trees may reach 35m tall, and 10m round. But chestnut is rarely planted to yield timber because some - though by no means all - of its trunks develop serious cracks called 'shakes.' which makes it hard to cut large planks from them.

In south-east England much chestnut is grown on the coppice system, to provide small poles. The woods are cut over every 12 years or so, and a fresh cluster of poles then springs out from the stump without further care or replanting. Most of the poles are cleft always by hand - into smaller pales which are bound with wire to make chestnut pale fencing. Each pale contains - for its thin cross-section, a great deal of heartwood, and it is therefore both very strong and remarkably durable.

figure 30

Flowering branch of Sweet chestnut in July (x|). Each slender catkin carries many groups of male flowers; a single male flower is seen above (X2). Clusters of female flowers arise near the base of certain catkins; a single cluster, seen on the left, consists of many leafy bracts and three (hidden) flowers, with tufts of styles protruding (Xli). Note the large simple, toothed, leaves.

figure 30

Flowering branch of Sweet chestnut in July (x|). Each slender catkin carries many groups of male flowers; a single male flower is seen above (X2). Clusters of female flowers arise near the base of certain catkins; a single cluster, seen on the left, consists of many leafy bracts and three (hidden) flowers, with tufts of styles protruding (Xli). Note the large simple, toothed, leaves.

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