Laburnum (Laburnum vulgare). (Edward Step)
Although the Laburnums of our parks and gardens have all come from seed, and themselves produce an abundance of it, we do not meet with wayside “escapes” as we might expect to do, having regard to the habit of the tree and the fact that it is comparatively indifferent respecting character of soil. Possibly a remark of Loudon’s may explain this. He says that rabbits are exceedingly fond of the bark, and it may be that they destroy any young trees that are unprotected by palings or netting. The tree produces such a glorification of many an ordinary suburban road, when its flowering time comes round, that one would like to note its effect as a common object of the hillside and the woodland, against a background furnished by our more sober native trees.
The Laburnum is at home in the mountain forests of Central and Southern Europe, but there is no record of its introduction to Britain. We do know, however, that it has been with us for more than three centuries, for Gerarde, in his “Herbal,” published 1597, refers to it as growing in his garden. It belongs to the great Pea and Bean family (Leguminosæ), and is very closely related to the Common Broom, whose solitary flowers those of the Laburnum’s drooping racemes nearly resemble. Ordinarily it is only a low tree of about twenty feet in height, but in favourable situations it may attain to thirty feet or more. Some of the larger Laburnums, however, are of a distinct species (L. alpinus).
The pale round branches are clothed with leaves that are divided into three oval-lance-shaped leaflets, covered on the underside with silvery down. Both leaves and golden flowers appear simultaneously in May, but from the fact that the latter are gathered into numerous long pendulous racemes, their blaze of colour makes the leaves almost invisible. Tennyson’s description of its flowering—”Laburnum, dropping wells of fire” —is fine, but we rather prefer Cowper’s “rich in streaming gold,” as embodying a more exact colour idea. The flowers are succeeded by long downy legumes or pods, like those of the bean and pea, containing many seeds, which are of a dangerously violent emetic character when introduced to the human stomach. The dark wood is of coarse grain; but, in spite of this, hard and enduring, and taking a good polish. It is chiefly used by musical instrument makers, turners, and cabinet-makers.
Laburnum is the old Latin name, which is thus rather fancifully explained by Prior, “an adjective from L. labor, denoting what belongs to the hour of labour, and which may allude to its closing its leaflets together at night, and expanding them by day.” Common local names are Golden Chain, suggested by the strings of flowers, and Bean-trefoile and Pea-tree, having reference to the leaves and legumes respectively.
LABURNUM ADAMI (syn Cytisus Adami).—A graft hybrid form between the common Laburnum and Cytisus purpureus, the result being flowers of the Laburnum, the true Cytisus purpureus, and the graft hybrid between the two. It was raised by Jean Louis Adam in 1825. It is a curious and distinct tree, worthy of culture if only for the production of three distinct kinds of flowers on the same plant.
L. ALPINUM (syn Cytisus alpinus).—Scotch Laburnum. Europe, 1596. This very closely resembles the common Laburnum, but it is of larger growth, and flowers later in the season. The flowers, too, though in longer racemes, are usually less plentifully produced. It grows 30 feet high. There is a weeping form, L. alpinum pendulum, and another with fragrant flowers, named L. alpinum fragrans, as also a third, with very long racemes of flowers, named L. alpinum Alschingeri.
L. CARAMANICUM.—Asia Minor, 1879. A bushy shrub of vigorous habit, with trifoliolate and petiolate leaves of a pale green colour, thick and tough, and brightly polished on the upper surface. Flowers bright yellow, the calyx being helmet-shaped and rusty-red. It is a beautiful but uncommon shrub, and succeeds very well in chalky or calcareous soil. Flowers in July.
L. VULGARE (syn Cytisus Laburnum).—Common Laburnum. Southern France to Hungary, 1596. This is one of our commonest garden and park trees, and at the same time one of the most beautiful and floriferous. The large, pendulous racemes of bright yellow flowers are, when at their best in May, surpassed neither in quantity nor beauty by those of any other hardy tree. There are several varieties of this Laburnum—a few good, but many worthless, at least from a garden point of view. L. vulgare Parkesii is a seedling form, bearing large racemes of deep-coloured flowers, often 14 inches long; L. vulgare Watereri was raised in the Knap Hill Nursery, Surrey, and is one of the most distinct and beautiful of the many forms into which the Laburnum has been sub-divided. The flower racemes are very long and richly coloured. L. vulgare quercifolium and L. vulgare sessilifolium are fairly well described by their names; L. vulgare fragans differs only in having sweetly-scented flowers; L. vulgare involutum has curiously-curled leaves; while L. vulgare aureum, where it does well, is a beautiful and distinct form.