|Acer japonicum is a tree in its native habitat and a large tree-like shrub in cultivation. This bushy, deciduous tree with rounded mid-green leaves turn red in the autumn. Small, red-purple flowers appear in April in long drooping corymbs. Leaves tend to scorch in hot, dry weather.
The cultivar, 'O Isami' ( 'Oh Isami', 'Oo Isami'), a treelike shrub is has large, deeply incised to about half the length of the blade with notched lobes measuring 6 to 8 inches across. The new growth is olive-yellow to pink and turns to dark green. In the autumn, the leaves change to scarlet, gold, yellow and orange with green.