Kalopanax septemlobus aka Tree Aralia

Kalopanax septemlobus is a deciduous tree in the aralia family. Gardeners call it castor aralia or tree aralia. Its range includes China, Japan, Korea, and far eastern Russia. It grows in cool, moist forests in its native range. Garden trees reach 40–60 feet [12–18.3 metres] tall and wide. Wild trees may reach 90–100 feet [27.4–30.5 metres]. It grows slowly and forms an upright, oval crown.

The tree has stout branches, with few smaller branches. Sharp spines cover young stems and parts of the trunk. As trees age, the trunk and larger branches lose spines. Older bark turns dark grey, with ridges and deep grooves. The simple leaves grow in an alternate pattern along stems. They are glossy, dark green, and toothed along their edges. Each leaf has five to seven lobes that spread like fingers. Leaves can span about 1.2 feet [0.36 metres]. Their shape recalls the leaves of castor bean. In autumn, they turn dull yellow to red.

Small white to greenish flowers open in July and August. They form rounded groups within broad panicles at branch tips. These panicles can span 1–2 feet [0.3–0.6 metres]. Bees gather at the flowers in large numbers. Small drupes follow, turning dark blue to black when ripe. They ripen in clusters during autumn and hold two seeds each. Birds eat the fruit and may help the tree reseed. Both the flowers and fruit add interest to the crown.

Grow this tree in full sun or light shade. It prefers deep, fertile soil that stays moist but drains well. Soil rich in organic matter suits it well. It accepts acidic, neutral, and alkaline soil conditions. Avoid dry ground, which does not suit its needs. Hot, humid summers in the deep South also cause problems. Sources place it in USDA hardiness zones 4–7. Its broad crown suits use as a shade tree. It also works as a single landscape tree or woodland planting. Sources report few major pest or disease problems. The spines remain a concern when handling branches.

Young leaves and shoots have food uses after cooking. Plants For A Future lists no known hazards. This does not establish safety for every use or animal. Reported traditional remedies use the bark, leaves, roots, and wood. These reports do not establish that such treatments work. The bark and leaves also have insecticide uses. Growers in China cultivate the tree for timber.