Mallotus cumingii is an
evergreen shrub or small tree growing up to tall, with a
trunk diameter of up to . The outer bark is grey to brown in colour and may be smooth or wrinkled, sometimes peeling away in patches. The leaves are oval in shape, measuring by , and may be hairy or
glabrous. The upper surface of the leaf is dark green and somewhat shiny with a paler underside.
M. cumingii is
dioecious and the
inflorescences are
racemes, produced singly or less commonly in a pair. Male plants produce inflorescences up to long, with sweet-scented white, cream, or yellowish flowers measuring up to in diameter and composed of 2–4 ovate
sepals surrounding a cluster of 30–60
stamens. Female plants produce inflorescences up to long, with faintly sweet-scented greenish flowers with a plumose
stigma measuring long. The fruits are rounded
indehiscent drupes measuring by . The exterior of the fruit is smooth to slightly wrinkled, hairy, and speckled yellowish green to reddish brown when fresh, turning brown or dark grey when dry. ==References==