Elm Trees
The English elm—in recent years much depleted by Dutch elm disease—is still in evidence, although the smaller wych elm is now more widespread.
The Elm family (Ulmaceae) comprises around 200 trees and shrubs found in tropical and temperate locations. The best-known members are the elms. There are about 20 species of elms, all large deciduous trees mainly occurring in the northern hemisphere.
Elm species can be difficult to distinguish from one another. Still, there are always two prominent leaf characteristics: one half of each leaf is always longer than the other, and each leaf has double teeth around the margins. The shoots and flowers have less distinctive but equally important features. The leaf shoots, arranged in five, are of different shapes and sizes. The terminal bud of most species withers, and the largest leaf comes from the second bud.
The flowers occur in clusters with the male and female parts together. They appear before the leaves on the previous year's twigs. Each flower is small with no sepals or petals, consisting of a bell-shaped, five-lobed cup of bracts containing the reproductive elements.
The six British elm species growing in our fields and hedgerows are challenging to recognise because they are similar, as most have hybridised. Eleven recorded British hybrids are better known than their parent species—it is rare to see a true species in the countryside.
There are four major Elm groups- the common or English elm, the wych elm, the smooth-leaved elms, and the hybrids, the Dutch elm.
Common Elm
The common elm was once a unique symbol of the English countryside although this elm is also found in Brittany and southeast France. It is predominantly a native of southern England and prefers well-drained valleys in areas such as the Midlands, the Home Counties and the south-west. Consequently, you rarely see it in the drier parts of eastern Kent and East Anglia, where other species, notably the smooth elms, are more common.
The common elm is a beautiful domed tree that has been immortalised in Constable's 1826 painting, 'The Cornfield'.
The mature tree has a massive, straight bole extending well into the crown and a few large ascending branches. The main limbs diffuse into dense, billowing profusions of curled shoots, giving a characteristic overall dark green or blackish appearance that you do not find with other elms.
The bark is dark brown and deeply fissured, forming large, squarish plates. Suckers flourish from buds hidden beneath the bark, especially at the base of the trunk, and crowd around the middle of the tree to give a distinct skirted appearance. The common elm also produces root suckers which can grow at a surprising distance from the parent trees and even form a hedge in some cases.
Usually, mature trees are stout with a long, densely leafy trunk and billowing crowns representing about a third of the height. However, many trees are cropped by hedge-cutters or foresters along the trunk, giving a naked 'lollipop' shape rather than the characteristic egg shape.
In all elm family members, the flowers cluster on one-year-old twigs appearing before the leaves form. These flowers are dark red, profuse and regular. The fruits are small and rounded, each one appearing as a dry or fleshy notched membrane surrounding a single seed. Some botanists think the seeds are sterile and cannot germinate and that the trees proliferate almost entirely from suckers. In reality, the seeds lose their germinating capacity after a few days and do not emerge through the seed coat unless they land on bare soil.
Elm leaves are about 10 cm long and 5 cm wide, varying in shape according to their position on the shoot. They emerge from slender, reddish-brown shoots that appear in the hedgerows in April, while those on larger trees appear in May and remain on the tree until November or December.
The Wych Elm
The wych elm can be distinguished from the common elm by several characters. Wych elms are not as tall as the common elms and grow into irregular rounded shapes up to 30m (100ft) high. The lower branches start to arch from near the base of the trunk, and the upper limbs appear twisted, growing tortuously into the upper crown.
The dull grey or blackish bark is smooth when young but becomes brownish-grey, fissured and ridged in mature specimens. The bark is another clue to the identity of mature trees: it appears twisted and parallel-ridged but never deeply furrowed like that of its close relatives.
The flowers have brightly coloured stamens with crimson or purple anthers and white filaments. The leaves may be up to 16cm (6in) long. on very short stalks. They are bright green and rough above and downy and rough on the underside.
Dutch elm disease
Dutch elm disease is a real misnomer since it is neither restricted to Dutch elms nor originated in Holland. The disease, a fungus infection affecting all elms, was discovered in France in 181 8, identified in Holland in 1919, and probably originated in Asia. First found in Britain in 1927, surveys showed that the disease was widespread. The first outbreaks declined, and although approximately 20% of the elms perished, many partly diseased trees recovered sufficiently not to damage the landscape too much. However, by the late 1960s, a new killer version of Dutch elm disease hit the British tree population. This epidemic has been so severe that the results have been headline news throughout the 1970s. This time the effect on the landscape has been devastating and the change irreversible. During this sad time, the Forestry Commission reported that more than 20 million trees died. Two-thirds of the elm tree population was removed from the countryside.
In areas with dense elm populations, wych elms and the smooth elms escaped relatively lightly because of their sporadic distribution. The highest incidence of Dutch elm disease occurred in Sussex, Essex, the Severn-Avon valley and Hampshire, where the common elm was most widespread.
However, some good news about elm trees in Brighton and Hove.
Links
https://www.bbc.co.uk/news/science-environment-50519036
References
The Living Countryside Series (1984) The Living Landscape. Page 8. Eaglemoss Publications Ltd & Orbis Publishing Ltd (Readers Digest)