It is a deciduous shrub or small tree growing to 4–6 m (rarely to 10 m) tall. The bark, light grey when young, changes to a coarse grey outer bark with lengthwise furrowing. The leaves are arranged in opposite pairs, 10–30 cm long, pinnate with five to seven (rarely nine) leaflets, the leaflets 5–12 cm long and 3–5 cm broad, with a serrated margin.
The hermaphrodite flowers are borne in large corymbs 10–25 cm diameter in mid summer, the individual flowers white, 5–6 mm diameter, with five petals; they are pollinated by flies.
The fruit is a dark purple to black berry 3–5 mm diameter, produced in drooping clusters in the late autumn; they are an important food for many fruit-eating birds, notably Blackcaps.