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.
LARDIZABALA BITERNATA.—Chili, 1848. Requires wall protection, there being few situations in which it will succeed when planted in the open. It is a tall, climbing shrub, with dark green persistent leaves, and bearing purplish flowers in drooping racemes in mid-winter. Planted in rather dry soil, at the base of a sunny wall, this shrub forms a by no means unattractive covering, the twice ternate, glossy leaves being fresh and beautiful the winter through.