Alder, European or Common
Alnus glutinosa
Betulaceae - Birch

Description

Leaves: Dark green, glossy, hairless above; paler green below with tufts of hair on veins; alternate; simple; oval to circular; 2" to 4" long; apex is rounded or notched; broadly wedge-shaped base; gummy when young; edges coarsely and doubly toothed; tufts of fine hair below where veins meet; veins in 6-8 pairs; petiole 1/2" to 1" long; some cultivars have lobed leaves; deciduous.

Twigs/buds: Twigs greenish-brown to brown, hairless, sticky. Buds on stalks; 1/4" to 1/2" in length; red to reddish purple; 2-3 scales that meet at edges.

Flowers/fruit: Flowers monoecious; small male flowers, reddish-brown, in 2" to 4" long catkins; purplish female flowers inside an egg-shaped cone. Fruit a winged nutlet inside a 1/3" to 2/3" egg-shaped cone (strobile) on a 1/2" to 1" long slender stalk; matures brown in October through November; cones stay on the tree for months or years, sometimes getting very dense.

Bark: Lustrous gray-green or green-brown when young, becoming glossy brown as it ages.

Wood: Unimportant in North America, though alder wood is very important in the Pacific Northwest; alder wood in general is light and soft with conspicuous rays, white to pinkish color, and indistinct heartwood; used in furniture, veneer, and carvings; diffuse porous.

General: Native across Europe to western Asia, and as far south as northern Africa. Locally naturalized on floodplains from the Northeast to the Midwest. Not shrubby like Utah's native alder, it is a nice upright, narrow-canopyed, medium sized tree. A nitrogen fixer. Often multi-trunked. Readily transplanted. Prefers wet sites, but survives on drier sites. Prefers full sun to partial shade.

Landscape Use: Fairly commonly planted in Utah. I have seen some very large, narrow canopyed European alders growing in Logan. These were a little unkempt, but otherwise nice and several cultivars are available. Female cones/strobiles are interesting and can stay on the tree a long time. Zones 3-7.

Cultivars: 'Aurea', 'Charles Howlett', 'Imperialis', 'Laciniata', 'Pyramidalis'.