Hornbeam

The natural habitat of hornbeam extends throughout Europe, from the Pyrenees to southern Sweden and east to Asia Minor, and it has been introduced and naturalized over a very much wider area. It is essentially a lowland tree. It thrives on similar sites as beech were there are rich loams and fertile clays, but is unlikely to progress as far up hillsides or grow as well as on thin, chalky soil.

In Britain, the hornbeam is only considered to be a native species in south-east England and in isolated areas in Somerset and Gwent. It is only hardy in southern England and sheltered microclimates further north, although established trees tolerate frost. The hornbeam grows well in partial shade and coexists with other broadleaved trees, to which it is frequently subordinate in mixed woodland. Well-rooted trees seldom blow over, but summer winds may dessicate the foliage. The seeds are a valuable source of autumn food for small birds, particularly tits and finches. Squirrels will take seeds but usually prefer larger, less labour-intensive fruits from other trees at this time of year. Woodmice and voles have plenty of time to clear up most of the seeds that fall to the ground, as seeds require 18 months to germinate.

There are records of introductions in the 15th century, at least as far north as Worcester and Norfolk. A few trees can now be seen in almost every part of lowland Britain, including the glens of Scotland.

Hornbeam woods are rare, being largely confined to the areas of clay soil around London, but the tree frequently occurs as part of a mixed broadleaved woodland elsewhere. The picture to the left shows neglected hornbeam coppice in Titsal Wood, Suffolk.

The traditional methods of managing hornbeam were usually pollarding or coppicing; the whole tree was seldom cut down and new trees were rarely planted. The tree was a favourite species for 'wood pastures' rather than forests. In a wood pasture, individual trees were grown on open grazing land, usually as pollards, at very wide spacing. The trees had almost no harmful effect on grass quality and it appears that domestic animals and deer did not seriously damage the bark of well-established trees or roots. Pollarding allowed the land beneath to be used for grazing. Ancient pollard hornbeams still stand in parts of Essex and Hertfordshire, and in Hatfield Forest pollarding continues in the traditional way to this day, on trees up to 300 years old. Some of these trees have a stem diameter of 130 centimetres (13 feet 5 inches in girth). Hornbeam was often harvested from 2.5-metre (8-foot) pollards, leaving the stem to regenerate a new crop of branches. Much of the wood, bundled as faggots, was used locally as a dense household fuel.

At one time, the hornbeam was the main source of very hard wood in Britain, usually in somewhat larger sizes than the equally prized boxwood. It was used to make mill cogs, piano parts, chopping blocks, and the like. Hornbeam charcoal was prized in the early days of iron making for producing a hot flame. These days it has only limited uses on a very small scale, mostly for high-quality craft items and first-rate firewood. However, the hardness of the wood was notorious for taking the edge off foresters' and carpenters' tools, so it is likely that the former avoided large fellings, and the latter had no need of huge timbers. The requirements for hornbeam wood to make hard wearing elements of rural machinery are now either obsolete or can be met by using iron and steel.

The hornbeam is often confused with beech. Although the leaves are similar in size and colour, and have parallel veins, the margins, unlike beech, are sharply double-toothed, vaguely resembling those of birch. The bark is pale silvery-grey, in which pale brown fissures develop with age. Old trunks become deeply fluted and heavily buttressed, and invariably develop an oval cross-section. If two measurements of the bole’s diameter be taken at right angles to each other, they will be found to differ greatly. A section of the trunk will not show a circular outline, but rather an ellipse, the bole appearing to have been flattened on two sides.

The heavy-branched crown is unevenly rounded and spreading, although freshly pollarded trees may develop a neat round head of branches for a few years before becoming irregular again. The shoots are dark brownish-grey with occasional silky hairs; they are thin and slightly angled between each bud. The alternate buds are sharply pointed and slender, like short beech buds, but tend to lie along the shoot rather than sticking out at an angle. The rough textured leaves are dark green with 9-13 pairs of pale, prominent, parallel veins. On the underside, each vein has a tuft of tiny white hairs at the point where it is joined to the midrib. The male catkins are very like those of birch except that they tend to be carried singly instead of in threes. The catkins appear as pendulous clusters of flowers, each consisting of a shared, light red outer bract and 12 yellow stamens. Although bunched tightly together, each of these in fact belong to three separate flowers. Female flowers are grouped towards the shoot tips where a cluster develops into a bunch of pale green, winged fruit in early summer. The seed wings have a unique and distinctive appearance: they consist of a 3-4-centimetre long tapered, papery bractiole with an enclosed flat seed at its base, flanked by two very small wings. The hornbeam is not known for rapid growth, but it does live for a very long time (over 300 years) and becomes an almost permanent landscape feature. In autumn, after a brief display of yellow and gold foliage colour, some trees will retain a few pale fawn-coloured dead leaves on their lower branches well into the winter. Fully ripe but dormant seed requires at least 18 months to germinate.

The tallest hornbeam on record in 1985 was in Cornwall at 30 metres (98 feet) tall. The largest diameter at breast height was measured in Hampshire and found to be 146 centimetres (15 feet in girth).

There are many cultivated forms of the hornbeam that are used as amenity or urban trees. The cultivar 'Fastigiata' is an ideal street tree because of its narrow crown spread, robust constitution, and fairly slow growth of 17 metres (56 feet) in 70 years.

//Left: Fastigiata, Colchester Ave, Cardiff, Sept 2006//

//In Suffolk the “Hornbeam” is called the Auburn, and sometimes the Arbor Tree; the latter, a corruption of the former. This tree never leaves the cold clayey soils, where it is to be found in every hedgerow; as the soil gets lighter, the Dutch Elm and Maple take its place//. (Loudon’s Arbortetum Britannicum) .