A deciduous tree of the largest size, often 100 ft high in its native state, with pendulous branches and a spirally twisted, furrowed trunk. The trunk is sometimes solitary, and 3 to 4 ft through, but more often the tree is made up of a group of several smaller stems. Leaves mostly opposite, but sometimes alternate towards the base of the shoot, broadly ovate or heart-shaped, 2 to 4 in. long, slightly scalloped on the margin, and glabrous except when young. The branch in its second year develops at each joint a short or almost obsolete twig, carrying a single leaf and flowers. The male and female flowers are borne on separate trees, but neither possesses any beauty; the males consist of a minute calyx and an indefinite number of stamens 1⁄2 in. long; the females of four larger, but still very small, green, fringed sepals, and four to six carpels (but in another nterpretation these ‘flowers’ are inflorescences). The fruits are small pods, 1⁄2 to 3⁄4 in. long, borne usually two to four together on a short stalk.
This tree for a long time was thought to be confined to Japan, where it is the largest of deciduous trees, reaching its finest development in the island of Yezo; but Wilson found it in China in 1910. One tree, still living, but with its top fallen away, he found to be 55 ft in girth of trunk. The timber is light, straight-grained and yellowish, and is highly valued. The finest trees I have seen in Europe were in the Imperial Garden at Sans Souci, near Berlin, where there was, in 1908, a singularly elegant tree 30 ft high, with slender, spreading, arching branches. It succeeds equally well in the Royal Garden at Hanover. Still finer trees, but of denser habit, are in the Arnold Arboretum, Mass. It is very hardy and evidently likes a continental climate. At Kew, where it was introduced in 1881, it is not a success. Like so many other North Asiatic trees introduced to this country, it commences to grow early in spring, and its young shoots are almost invariably ruined by frost; sometimes even the second growths meet the same fate. The tree is very valuable where late spring frosts do not prevail. The generic name refers to the resemblance of the leaves to those of the Juda-stree (Cercis).
The following are among the finest examples of this tree recorded recently: Westonbirt, Glos., 61 × 3 + 23⁄4 ft, 56 × 33⁄4 ft and 58 × 31⁄2 ft (1967); Lanarth, Cornwall, pl. 1908, 55 ft high on four stems, the thickest 33⁄4 ft in girth and with a spread of 64 ft (1966); Ashbourne House, Co. Cork, Eire, 52 ft high on two stems each 43⁄4 ft in girth (1966).
The Chinese form of this tree has been named var. sinense by Rehder and Wilson (see Plantae Wilsonianae, Vol. 1, p. 316). According to Wilson it differs from the Japanese type, which usually forms several trunks near the ground, in nearly always being confined to a single stem. The authors regard the leaf-stalk of var. sinense as shorter and the leaf itself not so markedly cordate as in the Japanese tree, but judging by a large series of specimens from both countries at Kew these differences are not very reliable. Wilson found trees up to 130 ft high and describes them as exceeding in girth and height all other deciduous, non-coniferous trees known from China.
In earlier editions of this work it was suggested that var. sinense turns red in the autumn and the Japanese type yellow, but now that the Chinese variety is better known it can be said with fair certainty that there is no difference between them in this respect. The autumn colouring of C. japonicum is in fact very variable both in tint and timing. The late Mark Fenwick, who planted many at Abbotswood in Gloucestershire, wrote (Journ. R.H.S., Vol. 65, 1940, p. 167): ‘One never knows when Cercidiphyllums are going to turn or what colour they will assume. Here they are seldom all red or all yellow, but generally assume shades of red, orange, pale yellow, pale pink, mauve and green.’
var. magnificum Nakai C. magnificum (Nakai) Nakai – In this variety the leaves tend on the average to be larger than in the type, more rounded in outline and more cordate at the base; seeds slightly longer, winged at both ends. It makes a smaller tree than the type and differs too in its bark, which remains smooth until the tree is of some age. Native of the main island of Japan, where it occurs in scattered localities in the mountains; first described in 1920. There is a specimen about 25 ft high in Windsor Great Park and younger trees in the Kew collection.