Trochodendron aralioides aka Wheel Tree

Trochodendron aralioides is an evergreen shrub or tree called wheel tree. It belongs to the family Trochodendraceae. Kew places its native range from central and southern Japan to Taiwan. It grows in mountain forests. Some garden sources also list Korea within its range. In the wild, it may start life on another tree. It can grow on the trunk of a Japanese cedar.

Growth is slow, and garden plants often stay shrubby. Most reach 10–20 feet [3–6.1 metres] tall. Their spread is about 10–15 feet [3–4.6 metres]. RHS describes cultivated shrubs near 10 feet [3 metres], with larger plants reaching 26 feet [8 metres]. Wild trees can reach 60 feet [18.3 metres]. Plants may have one trunk or several, with spreading, near-horizontal branches. The light gray bark has a scent. Leaves cluster near branch tips, leaving much of each branch bare. They feel thick and leathery, with glossy tops and paler undersides. Their edges have small teeth or rounded scallops. Some leaves gain bronze and red tones in autumn.

Flowers appear from April to June, though young plants may take years to bloom. The small green to yellow-green flowers grow in upright racemes. Each cluster can hold 10–20 flowers or more. The flowers lack petals. Their stamens spread outward like wheel spokes, which explains the common name. Woody, star-shaped fruits follow the flowers. Each fruit contains four to eleven follicles. They reach about 0.06 feet [0.02 metres] across.

Give wheel tree fertile, moist soil that drains well. Loam suits it best, though it accepts other soil types. Neutral to slightly acid soil suits its needs. It grows in full sun but favors dappled or afternoon shade. Keep moisture steady, since drought causes problems. It tolerates wet soil and some brief flooding. Shelter it from strong, cold, drying winds. Missouri Botanical Garden recommends USDA zones 6–7; NC State also lists zone 8. RHS rates it H3 for UK conditions. These ratings reflect different regional growing conditions.

Use it as a specimen shrub, understory tree, or light-shade tree. Its evergreen leaves give gardens winter structure. RHS also lists screens, hedges, and cut flowers as uses. It needs little or no pruning. Choose its site with care, since established plants resist moving. No serious pest or disease problems are reported. Propagate it from seed or summer semi-ripe cuttings.