This species, widely distributed in the Himalaya and the Far East, is closely related to the common spindle-tree, differing in having the anthers purplish or reddish purple instead of yellow. It is a deciduous or semi-evergreen shrub or a small tree up to 30 ft high. Leaves variable, in size, shape, and relative width, broadest at or slightly below the middle, but sometimes oblanceolate to obovate, 21⁄2 to 6 in. long, 3⁄4 to 21⁄2 in. or slightly more wide, shortly toothed, glabrous on both sides or downy on the veins beneath. Capsules pink, four-lobed; aril orange to blood-red, sometimes split and exposing the seed.
E. hamiltonianus is a taxonomically difficult group, in need of detailed study. It does not subdivide neatly, but plants from the north-eastern corner of its range are distinct in their slender leaves (see var. maackii). Plants from Japan, S. Korea, and Sakhalin have been separated from E. hamiltonianus as E. sieboldianus, but all the characters given by Rehder to distinguish this species can be found in Himalayan plants. Komarov placed E. sieboldianus under E. hamiltonianus as a variety and gave as the difference that in var. sieboldianus the flowers are heterostylous: those with long styles have stamens with short filaments and vice versa, whereas in typical E. hamiltonianus the tendency is for flowers with long styles to have long filaments and vice versa (C. Jeffrey, Bot. Mag., n.s., t. 548). It is possible that there are also statistical differences in size and shape of leaves and fruits, etc. The Japanese plants, like those of China and the Himalaya, are variable, and Koehne’s three “species” – E. yedoensis, E. semiexsertus, and E. hians – represent slightly differing forms and were described from cultivated plants. See further below, under var. sieboldianus.
Typical E. hamiltonianus is represented in cultivation by plants known by the synonymous name E. lanceifolius; these were probably all raised from Wilson’s No. 1105, collected in W.China during his expedition for the Arnold Arboretum. They are semi-evergreen, vigorous large shrubs or small trees up to 30 ft high, but do not fruit freely. Wilson also sent seeds from W. China when collecting for Veitch (W. 1202), and the material figured in Bot. Mag., n.s., t. 181, came from a plant at Kew raised from this number.
var. maackii (Rupr.) Komar. E. maackii Rupr.; E. europaea var. maackii (Rupr.) Reg. – Leaves narrow-elliptic to lanceolate, mostly 21⁄4 to 4 in. long, 3⁄4 to 1 in. wide (smaller on the flowering twigs), tapered at both ends, the apex acute, acuminate or even caudate, dark green above, paler beneath, edged with fine incurved teeth; leaf-stalk 1⁄4 to 3⁄4 in. long. Flowers and fruits as in typical E. hamiltonianus, but the inflorescences are perhaps fewer-flowered on the average. Native of the Russian Far East, Korea, and N.E. China; described (as a species) in 1857 from specimens collected by Richard Maack on the Amur River; introduced to Kew before 1880.
var. sieboldianus (Bl.) Komar. E. sieboldianus Bl.; E. hamiltonianus subsp. sieboldianus (Bl.) Hara; E. yedoensis Koehne; E. hians Koehne; E. semiexsertus Koehne; E. nikoensis Nakai; varieties based by Blakelock on the preceding four species; E. vidalii Fr. & Sav. – This variety is mainly represented in gardens by the plants called “E. yedoensis”, with obovate or elliptic leaves up to 5 in. long and 3 in. wide, pink capsules and seeds with an orange almost closed aril. Plants were in commerce under this name before Koehne formally described the “species” in 1904, and are believed to have been introduced from Japan by the American nurseryman Parsons about 1865. In autumn the leaves turn to various shades of rose and red and make a lovely combination with the pink fruits. But the autumn colour varies, either because it depends on soil and situation, or because there is more than one clone in the trade. Another form of the Japanese spindle-tree was named E. semiexsertus by Koehne. In this the aril is open on one side, exposing the true seed-coat.