Acer truncatum aka Shantung Maple

Shantung maple, Acer truncatum, is a deciduous tree in the soapberry family, Sapindaceae. It comes from northern China, Manchuria, Korea and the Amur region of the Russian Far East. Some sources also list Japan within its range. Other common names include Shangtung maple and purpleblow maple. The species name means cut off square, a nod to the flat base of many leaves.

In gardens it forms a small tree with a dense, rounded crown and regular branching. Most trees reach 20 to 25 feet (6 to 7.5 m) tall and 15 to 20 feet (4.5 to 6 m) wide. One source puts some trees at 30 feet (9 m), and another cites up to 45 feet (14 m). Growth is slow, and the RHS gives up to 50 years to reach full size.

The leaves are opposite and simple, 3 to 6 inches (8 to 15 cm) across. Each has five triangular lobes with smooth edges, and the two lowest lobes stretch outward. New leaves open reddish purple and turn glossy dark green. Autumn colour runs from yellow and orange to red, sometimes with purple. A broken leaf stalk bleeds milky sap, a handy identification clue. Young bark has a purple tinge and warty texture. Older trunks turn gray-brown, rough and fissured. Twigs are reddish brown and smooth.

Small greenish-yellow flowers open in upright clusters called corymbs in April and May. They are large for a maple but have little ornamental value. Paired winged samaras about 1 to 1.5 inches (2.5 to 4 cm) long follow. The wings spread at roughly a right angle, and the fruit ripens in early autumn.

The tree grows in full sun or part shade, and full sun gives the best shape. It likes moist, well-drained, humus-rich soil. Sources favour acid soil, though the RHS accepts chalk, clay, loam and sand across a range of pH. Once established, it copes well with heat and drought. Trees have thrived even in compacted, dry ground. It is hardy in USDA zones 4 to 8, and rated H7 in the UK. Pruning needs are minimal.

Its modest size suits small yards, patios and streets, including planting beneath utility lines. It also works as a specimen in an Asian-style garden. Maple foliage feeds imperial moth caterpillars. The seed is edible when roasted, but it is small and fiddly. People have packed the leaves around apples and root crops to help store them.

Most sources report no serious pest or disease problems. The RHS notes possible attack from gall mites, aphids, caterpillars and horse chestnut scale. Verticillium wilt, leaf scorch and honey fungus can also occur. Tar spot has been seen on trees in Connecticut. No hazards are recorded for this species.