A small deciduous tree or large shrub, with slender branches. Leaves oblong or obovate-oblong, 4 to 6 in. long, the apex contracting rather abruptly to a point, rounded at the base, dark green and glabrous above, glaucous and downy beneath, usually with seven to nine pairs of veins; leaf-stalk 3⁄4 to 1⁄2 in. long, pubescent when young. Flowers fragrant, at first cup-shaped, borne on a stalk 1 to 21⁄2 in. long; petals pure white, about 2 in. long, obovate, very concave. Stamens numerous, forming a rosy-crimson or maroon-crimson disk 1 in. across. Fruit 2 in. long, carmine; seeds scarlet. Bot. Mag. t. 7411.
Native of S. Japan and Korea; probably first introduced to Britain around 1879 by Messrs Veitch (but the plant originally grown at Kew came from Yokohama in 1893). The most distinctive character of the species is the comparatively long flower-stalk; also, the flowers, instead of being fully pendent as in the allied M. wilsonii and M. sinensis, have a more horizontal poise and ‘look you in the face’ (as Millais put it). The flowers are not always borne in one crop but appear often a few at a time from May until August on the leafy shoots. The crimson stamens show in attractive contrast to the white tepals.
M. sieboldii varies in the colour of its stamens, from pinkish (in a very poor form sometimes still seen in gardens) to rosy-crimson and maroon-crimson. In the catalogue of the winding-up sale of Veitch’s Coombe Wood nursery Lot 895 was described as having the stamens ‘deep claret’, but whether this was their original form or a newer introduction is not known. The form with the brightest crimson stamens is believed to have been raised from seeds collected by Wilson in Korea in 1918. M. sieboldii is generally reckoned to be hardy, though there are reports of plants having been badly damaged or even killed in severe winters; having a wide north-south range it is likely to vary in this respect. It will grow 12 to 15 ft high and as much through (even larger in favourable situations). It is not suitable for chalky soils.
M. (sieboldii × tripetala) ‘Charles Coates’. – Three self-sown seedlings were noticed in the Azalea Garden at Kew by C. F. Coates, then foreman-propagator in the Arboretum. These were grown on, and when they flowered in 1958 it was established that they were hybrids of the above parentage. The leaves resemble those of M. tripetala in shape but are smaller and have long hairs on the midrib beneath. The flowers resemble those of M. sieboldii in shape but are held erect as in M. tripetala, and are cream-coloured. They are borne in mid-May and very fragrant. Stamens bright magenta (J. R. Sealy, Gard. Chron., Vol. 152 (1962), p. 77).