A magnificent tree in its native range but rarely thriving in north-west Europe. Growers are mainly interested in its genetic resistance to ash dieback. Introduced by 1891.

Native to the far east of Russia, central China, and to northern and central Japan.

Dioecious. Wind-pollinated. Wind-dispersed.

Medium (20m, 30m natively). Twigs grey, glabrous; buds opposite, dark brown, with a semi-circular leaf scar. Autumn foliage golden yellow. Leaves compound pinnate, large (20-35cm), with 9-11 oblong-lanceolate leaflets (5-10cm), dull green with scattered bristly hairs above, paler and conspicuously bristly below (especially along the midrib), serrate, almost stalkless, the rachis winged above. Flowers (not seen in Britain or Ireland) before the leaves; female trees bear a winged samara (3-4cm).

Hardy to -15°C but very sensitive to spring (even early) frosts. Thrives best in sheltered, damp sites, avoiding frost hollows, and is best grown near the coast in mild southern Britain and Ireland; even then it is unlikely to flower or seed. Tolerant of urban pollution.

No notable associations where introduced.

This species coevolved with Hymenoscyphus fraxineus, the ash dieback fungus, and tolerates colonisation of its leaves; though the fungus completes its lifecycle there, it seems unable to spread into shoots and stems, so trees avoid the phloem damage that kills most other ash species.

An occasional ornamental. Potential source of genetic diversity for tree breeding research in the battle against pests and disease.