The Green Alder (Alnus viridis) is an alder with a wide range across the cooler parts of the Northern Hemisphere.
It is a large shrub or small tree 3 - 12 m tall with smooth grey bark even in old age. The leaves are shiny green, ovoid, 3 - 8 cm long and 2 - 6 cm broad. The flowers are catkins, appearing late in spring after the leaves emerge (unlike other alders which flower before leafing out); the male catkins are pendulous, 4 - 8 cm long, the female catkins 1 cm long and 0.7 cm broad when mature in late autumn, in clusters of 3 - 10 on a branched stem. The seeds are small, 1 - 2 mm long, light brown with a narrow encircling wing. The Green Alder has a shallow root system, and is marked not only by vigorous production of stump suckers, but also by root suckers.
The Green Alder is a light-demanding, fast-growing shrub that grows well on poorer soils. Unlike some other alders, it does not require moist soil, and is a colonist of screes and shallow stony slopes. It also commonly grows on subarctic river gravels, particularly in northern Siberia, Alaska and Canada, occupying areas similarly disrupted by ice floes during spring river ice breakup; in this habitat it commonly occurs mixed with shrubby willows.
