Phellodendron amurense Seeds | Amur Cork Tree

Small, black, shiny Amur Cork Tree seeds with a hard coat, on a plain background — Amur Cork Tree (*Phellodendron amurense*): Rutaceae, native to the cold woodlands of eastern Asia.

LATIN NAME: Phellodendron amurense

COMMON NAME: Amur Cork Tree, Amur Cork

Plant Profile

Amur Cork Tree is a deciduous tree of the citrus family, reaching fifteen metres with a broad, rounded crown and compound, bright-green leaves that turn yellow in autumn and smell of turpentine when crushed. Its most distinctive feature is its bark: thick, soft, corky and deeply furrowed, it can be pressed with a thumb and was once used for insulation and for floats.

It grows in the cold woodlands of eastern Asia, from the Amur region of Siberia through Manchuria and northern China to Korea and Japan, and it has been planted in Europe and North America as a shade tree. In Chinese it is huang bo, yellow bark, and its inner bark is a major medicinal herb.

Science & Biotechnology

The inner bark contains berberine, palmatine and other isoquinoline alkaloids, which give it its yellow colour and its bitter taste. Berberine has been studied extensively for antimicrobial and metabolic effects, and the bark is one of the standard sources of the compound in Chinese pharmacy.

The species is dioecious, with male and female flowers on separate trees, so only the female plants carry the black berries that hang in clusters in autumn. Its corky bark is an adaptation to fire and to cold, and it is one of the thickest barks of any temperate tree.

Uses & Benefits

The inner bark is used in Chinese medicine for damp-heat conditions, for diarrhoea and for skin infections, usually as a decoction or a powder. The cork is used for insulation, for floats and for bottle stoppers, and the timber for furniture and for gunstocks.

In the garden it is a shade tree for a large space, grown for its corky bark, its handsome foliage and its yellow autumn colour. It is tolerant of drought and of poor soil, but it seeds freely and has become invasive in parts of the eastern United States. The cork is stripped from felled trees rather than living ones, since the bark does not regenerate in the way that cork oak does.

Growing from Seed

Sow in autumn in a pot of loamy compost and leave it outside for the winter; the seed needs a cold, moist period, and germination may be slow and uneven. Sow fresh seed where possible, since viability declines in storage.

Plant out in sun or part shade in any well-drained soil, and water through the first two summers. The tree is fast-growing and tolerant of drought once established, and it needs little pruning beyond the removal of dead wood. If seedlings are not wanted, remove the female trees or the seed clusters before they ripen. Seedlings transplant poorly once the taproot has formed, so plant them out young.

Our Take

A cold-hardy shade tree with corky bark and yellow autumn colour, and the source of the berberine-rich herb huang bo. Give it space, and watch for its seedlings in a mild climate.

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