The status of species for this tree is accepted by Dr Stephen Spongberg in Journ. Arn. Arb., Vol. 60, pp. 367-76 (1979). Other distinctions he gives are: leaf-bearing twigs produced by the long shoots in their second year better developed than in C. japonicum, with persistent stipules (deciduous in the other species); stipules on the long shoots fully connate (against free or only connate at the base). It is confined to the main island of Japan, whereas C. japonicum is of wider range in that country and also occurs in China.
Hybrids between the two species occur. Pendulously branched trees, known both from the wild and in cultivation, agree better with C. magnificum than with C. japonicum but some may be hybrids (Spongberg, op. cit., and K. E. Flinck in Int. Dendr. Soc. Year Book 1981, pp. 122-3).