A low, deciduous shrub from 1 to 11⁄2 ft high; branchlets glabrous or nearly so, well furnished with trifoliolate leaves. Leaflets obovate, 1⁄4 to 1 in. long, stalkless themselves, but with a common stalk 1⁄4 to 1 in. long; usually quite glabrous, dark green. Flowers purple, produced in May on the shoots of the preceding summer, one to three of them at each joint. Each flower is 3⁄4 in. long; the calyx 1⁄3 to 1⁄2 in. long. Pod quite glabrous, 1 to 11⁄2 in. long, containing three or four seeds. Bot. Mag., t. 1176.
Native of the S. Alps and S.E. Europe; introduced in 1792. In the colour of its flowers it is one of the most distinct of brooms, and one of the most charming of dwarf shrubs. It makes an admirable cover for the ground beneath a group of taller, thinly planted shrubs. A good system of cultivating it is to cut out the flowering shoots as soon as the flowers have faded, leaving the young growths that always spring up from near the ground to form the flowering shoots for the following year. Seeds provide the best means of propagation, and a sufficient quantity of them should, of course, be left to ripen for the purpose.
f. albus (Sweet) Zab. – A white-flowered form found wild near Bolzano and Trento and other parts of the Italian Tyrol.
A number of other colour variants have arisen in cultivation, with flowers in some shade of pink or of a richer purple than in the wild plant. An erect form is also known, and one with drooping branchlets.