A deciduous bush 8 to 16 ft high, or occasionally a bushy-headed tree up to 20 ft high; young shoots glabrous, grey by autumn, ultimately chestnut brown. Leaves ovate, sometimes obovate, with a long, tail-like point, and a usually rounded base, sharply and doubly toothed; thinly hairy when young, chiefly on the veins, 11⁄2 to 31⁄2 in. long, 1 to 13⁄4 in. wide; stalk 1⁄2 to 3⁄4 in. long, glabrous. Flowers opening in May, solitary or in twos or threes, each on a glabrous or thinly hairy stalk 1⁄2 to 11⁄4 in. long; they are 3⁄4 to 1 in. wide, white or pale pink. Calyx-tube glabrous, funnel-shaped to bell-shaped; petals rounded and entire or notched at the end. Fruits black, globose, 1⁄3 in. wide.
Native of Japan; introduced to the Arnold Arboretum in 1915. There has been considerable confusion between this species, P. incisa, and P. apetala, all three distinguished by having black fruits and a leaf with a long tail-like apex and a conspicuous double toothing. It is distinct enough in other respects from P. apetala (q.v.), a cherry very downy or hairy in many of its parts. P. incisa is also more or less downy on the young shoots, leaf-stalk and calyx, the leaves are smaller, the branchlets never become bright brown as in P. nipponica, and the flowers are normally smaller.
var. kurilensis (Miyabe) Wils. P. ceraseidos var. kurilensis Miyabe; P. kurilensis (Miyabe) Miyabe – This differs in having larger flowers and a downy leaf-stalk, calyx-tube, and flower-stalk. Native of N. Japan, the Kuriles, and Sakhalin; introduced to the Arnold Arboretum in 1905 and soon after to Britain. It is of dwarf habit and slow-growing in cultivation. The plant at Kew differs from the one grown as typical P. nipponica in its stiff, erect habit, larger calyx-tube, and more exserted stamens.
P. ‘Kursar’. – A hybrid raised by Collingwood Ingram from seed of P. nipponica var. kurilensis. It is one of the finest of the early cherries, bearing flowers of a remarkably vivid shade of pink in March, before the leaves; calyx and filaments of stamens dark red; pedicels hairy. It makes a vigorous fairly erect tree and colours orange in the autumn. A.M. 1952.
The name ‘Kursar’ was given by Capt. Ingram in the belief that the pollen- parent was P. sargentii. He now thinks there must have been an accidental exchange of labels, and that the pollen really came from P. campanulata, which he had crossed with P. nipponica var. kurilensis at the same time. He points out that P. sargentii is unlikely to have yielded a hybrid with flowers of such a deep pink (A Garden of Memories, pp. 181-2).