Small shrub, (0.1-)0.3-3 m; young shoots scaly, sometimes also puberulent. Leaves (2.5-)3.5-7.5 x (0.8-)1.1-2.8 cm, lanceolate to narrowly elliptic, apex acute or acuminate, upper surface with midrib puberulent, also hairy towards base of lamina, lower surface with large distant brown scales. Flowers 2-3(-4), in a loose terminal inflorescence; calyx with lobes absent or to 2.5 mm, frequently ciliate; corolla pale yellow, unspotted, zygomorphic, funnel-campanulate, 18-24 mm, outer surface scaly, somtimes also puberulent; stamens 10; ovary scaly, impressed below the declinate, glabrous style. Flowering April-May. Royal Horticultural Society (1997)
Habitat 600-1,850 m
RHS Hardiness Rating H5
Conservation status Least concern (LC)
An evergreen shrub 6 ft high in the wild; young branches slightly scaly. Leaves 11⁄2 to 21⁄2 in. long, 3⁄4 to 11⁄4 in. wide, oval-oblong, pointed at the apex, rounded or tapered at the base, more or less scaly on both surfaces, but especially beneath; stalk about 1⁄4 in. long. Flowers pale, rather dull yellow, 11⁄4 to 2 in. across, in clusters of about four or five; corolla broadly bell-shaped; calyx undulated into five very shallow lobes; stamens ten, slightly downy; flower-stalk scaly, 1⁄2 to 3⁄4 in. long. Blossoms in April and May. Bot. Mag., t. 8300. (s. and ss. Triflorum)
Native of Japan from the main island southward as far as Yakushima; introduced in 1908 and quite hardy. It is a rather variable species, both in habit and in the size and shape of its leaves. In his collection at The Grange, Benenden, Kent, Capt. Collingwood Ingram has a tall-growing plant which he considers to be a good match for typical R. keiskei, in which the leaves are lanceolate, acute, up to 3 in. long and 3⁄4 in. wide, and the petioles bristly when young. The commonly cultivated form, by contrast, is of low-growing habit and has shorter and relatively broader leaves, which are obtuse or subacute at the apex, with a stout midrib and glabrous petioles. Ingram considers the latter to represent a distinct species, which he has named R. laticostum (R.C.Y.B. 1971, pp. 28-30). These two cultivated forms are certainly very distinct, but the difference would probably be much less clear-cut if a wide range of wild specimens were examined. In the same article, Ingram published a second species, R. trichocalyx, described from a cultivated plant. He informs us that he is now satisfied that the plant in question is a hybrid of garden origin.
Shrub, 1-2m; leaves 3-9 x 1.1-2.8cm; flowers yellow.
Awards AM 1929 (H. White, Windlesham); flowers pale yellow.
Dwarf shrubs, 10-15cm tall; leaves 1.5-2.5 x 1-1.5cm; flowers yellow.
Awards AM 1970 (B.N. Starling, Epping Upland, Essex) to a clone of var. ozawae, ‘Yaku Fairy’; habit very dwarf, flowers yellow. AGM 1993, to a clone of var. ozawae, ‘Yaku Fairy’.
The dwarf forms of this distinctive species, especially those of var. ozawae from Yakushima, are good rock garden subjects.