The green alder - The Stelvio National Park

Alnus viridis

Alders (Alnus sp.) are deciduous plants and most of them will grow into trees. Some thirty species are native to the Northern hemisphere, occurring in Europe, North America, Asia and North Africa. They thrive in virtually all soil types, but prefer damp sites and are often found along streams.

Characteristics of the species

Green alder (Alnus viridis) is a rather large shrub (2-4m), with dense, upright branches. It is found in avalanche channels and in the field layer of woodlands on wet ground.
Its leaves are round or oval-shaped, long and pointed, and double-toothed along the edge. They are 6 x 4.5cm large, green on the upper side and paler in colour on the lower side of the leaf.
The catkins are, however, the most characteristic part; these consist of a pendulous inflorescence bearing the flowers. Male catkins are 5-12cm long and yellow in April-May, which is also the time when the leaves come out. Female catkins, instead, form small “cones”, fruits that hang down from the twigs in groups of 3-8; these are green in the summer and reddish-brown in the winter.

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