A deciduous bush 3 to 5 ft high, of spreading habit; young stems semi-woody, covered like the flower-stalks, leaf-stalks, and the underside of the leaves, with a close grey felt. Leaves opposite, ovate; 1 to 3 in. long, 1⁄2 to 11⁄4 in. wide; the base more or less broadly wedge-shaped, the apex blunt or pointed; coarsely toothed, almost lobed, dull green and downy on the upper surface; stalk 1⁄4 to 3⁄4 in. long. Flowers bright violet-blue, produced during October in hemispherical cymes from the axils of the uppermost leaves; main flower-stalk 3⁄4 to 11⁄2 in. long. Corolla downy, tubular, 1⁄4 in. long, with five lobes at the mouth; the four upper ones ovate, the lower one larger, scoop-shaped, and fringed; stamens four, much protruded; calyx funnel-shaped, with five-pointed teeth. Bot. Mag., t. 6799.
Native of China and Japan; originally introduced in 1844 by Fortune, who found it wild near Canton. It was at first treated as a greenhouse plant, and being scarcely worth its room there, was eventually lost until re-introduced by Maries in 1880. It is hardy at Kew in all but the hardest winters, and during a fine autumn makes a very pretty display. The leaves are pleasantly scented. It is increased with the greatest ease by means of soft cuttings in heat, and should be grown in an open, sandy soil, and given a sunny, sheltered position.
f. candicans (Schneid.) Hara – A form with white flowers found wild in Japan. As grown in gardens, it is perhaps less hardy than the type.
C. tangutica was described by Maximowicz in 1881 from specimens collected by the Russian traveller Przewalski in Kansu, whence Farrer introduced it about 1915 under his number 305. Farrer's plants differ from C. incana, as seen in cultivation, in their smaller leaves and have the lip of the corolla less divided. They are also hardier and earlier to flower. However, C. tangutica is no longer considered to be a distinct species.