Origin: Europe and Asia
Grey alder is a medium-sized tree with a cone-shaped crown.Read more about Tree, Bark, Twigs
Leaves are broadly oval, with doubly toothed edges and hairy stalks.Read more about Leaves
Flowers are tiny, clustered in separate male and female catkins.Read more about Flowers
Fruits are nutlets borne in brown, woody, conelike catkinsRead more about Fruit
Twigs are greyish-brown and hairy. Buds are downy, 6 - 12 mm (1/4" - 1/2") long, borne on short stalks.
Leaves are 5 - 10 cm (2" - 4") long, broadly oval, with a wedge-shaped or rounded base and a pointed tip.
Flowers tiny, clustered in separate male catkins and cone-like female catkins on the same tree. Flowers open in early spring, before the leaves.
Fruits are nutlets borne in cone-like catkins (alder cones) that are green and closed while maturing.
Mature alder cones are brown, woody, 13 - 16 mm (1/2" - 5/8") long, their scales opening to release the winged nutlets in late fall.
Empty alder cones remain on the tree through the winter and can be seen with the new green cones the following summer.
Distribution and related species
Grey alder, one of several subspecies of Alnus incana, is native to Europe and western Asia. Grey alder and its cultivated varieties (cultivars) are medium-sized trees that are frequently planted in Europe, less so in North America. Another subspecies, speckled alder, is native to northeastern North Amercia. It is a tall shrub or at most a small tree of wetland habitats. These two subspecies can be distinguished from European black alder, Alnus glutinosa, by their leaf tips. Black alder never has pointed tips while speckled and grey alder usually do.
Derivation of names
The genus name Alnus is the classical Latin name for alder. The species name incana is from the Latin for pale grey, a reference to the pale grey bark and undersides of the leaves.
Many species of alder are planted to improve soil quality because they have nitrogen-fixing bacteria on their roots. The fallen leaves of alders also help to fix nitrogen into the soil.
Grey alder's place in Toronto's urban forest
Grey alder is occasionally planted in Toronto's parks and cemeteries. In winter, alders are good places to observe winter birds which pick the seeds from the alder cones.
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