Its common name describes the unusual trait among trees of dropping leaves while still green in autumn. A neophyte in Britain and Ireland, introduced 1820.

Native to alpine and subalpine areas in Europe, including Austria, France, Germany and Switzerland. Uncommon in Britain and especially in Ireland as a naturalised tree.

Syn. Alnus viridis. Monoecious. Wind-pollinated. Seeds dispersed by wind and water. A fast-growing pioneer species. Short-lived (60–100 years).

Short (12m), often multi-stemmed and sometimes prostrate. Bark silver-grey to brown with prominent white lenticels. Twigs brown, shiny and usually glabrous; buds conical, green-purple, sticky, barely stalked. Leaves ovate, 3-15cm, coarsely and sharply double-serrate, downy beneath. Unusually for alders, flowers appear after the leaves: male catkins 4-8cm, female small (10-15mm) in clusters of 3-10, becoming woody and cone-like.

This is a very tough and hardy pioneer species, capable of growing in a wide range of sites from wet soils to mountain-sides. It is one of the first species to colonise bare ground following an avalanche in mountain areas.

An important ecosystem engineer in creating habitat in mountain areas.

Cryptodiaporthe oxystoma, a fungus causing dieback.

Useful in restoring ecological condition of damaged or challenging sites.