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OHIO BIG TREES
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America's forestry movement actually started in Ohio with the creation of the American Forestry Association in Cincinnati in 1875.

Division of Forestry
2045 Morse Rd.
Building H1.
Columbus, OH 43229

European Black Alder (Alnus glutinosa)
A deciduous tree from the Birch Family (Betulaceae)

4-7
25'
60'
rapid
full sun
part shade
pyramidal to
flat-topped
prefers moist/wet
European Black Alder, a native of Europe, northern Africa, and western Asia, was introduced to North America long ago and has escaped from cultivation, and it is sometimes seen along bodies of water, where it may successfully self-sow and form pure stands. Today, it is grown as a shade tree in urban areas, or at wet sites (ponds, creeks, drainage ditches, etc.) where it thrives and provides both erosion control and ornamental appeal.

Its leaves easily flutter in the breeze, and forms are available that are cutleaf (leaves having deep sinuses that give them a much finer texture). In addition, columnar forms exist for narrow spaces.

In late winter, its emergent pendulous catkins sway in the breeze, providing early ornamental appeal. Trees found in the open may reach 60 feet tall by 25 feet wide. As a member of the Birch Family, it is related to the Birches, Hornbeams, Filberts, and Hophornbeams, in addition to other Alders.

Planting Requirements - European Black Alder is adaptable to a wide range of favorable or harsh environmental conditions. It prefers moist to wet soils of variable pH that are rich and deep, but adapts to average or poor soils that are dry in summer. Growth is especially rapid in occasionally wet to permanently wet areas, such as floodplains , streambanks, and ditches. Black Willow is a good companion tree with a much finer texture. It is a good pioneer species of cut-over sites, and will self-sow to form a colony of saplings within a few years of initial seed production. It grows in full sun to partial shade, and is found in zones 4 to 7.

Potential Problems - European Black Alder, while capable of having a few minor disease and pest problems, is usually trouble-free.
Leaf Identification Features
European Black Alder has a leaf that is atypical as compared to other Alders in that it is round in shape, rather than elliptical. In addition, some leaves have a distinct notch at the apex, which is not obvious until the leaves are fully expanded.
As one would expect from a member of the Birch Family, the glossy alternate leaves of European Black Alder easily flutter in the breezes of summer. Growth is rapid for this stately tree, which often goes from a pyramidal to flat-topped shape as it matures.
Other Identification Features

Formation of green male and female floral buds occurs by mid-summer on the same tree in European Black Alder (making it a monoecious species), and these structures become more obvious with the abscission of leaves in autumn.

With the warmer days of mid-winter, the male floral buds begin to elongate and are called catkins, while the female flowers often lie close by, looking like miniature knobs.

The fertilized female flowers become cone-like, green fruits by late spring, and as they grow throughout the summer, they often weight down the branchlets that support them.

In autumn, the seeds are released as the cones open, and by winter the remaining structures (called strobiles) persist on the twigs.

Vegetative buds of European Black Alder are more typical of all Alders, being distinctly valvate (also called duck-billed, where the twin bud scales come together like a duck's bill) and also clearly stalked on the winter twigs.

The immature bark found on the limbs of European Black Alder is dark gray, interrupted by long dark fissures.

This becomes black plates and scales with age on the trunks, exposing a lighter gray to gray-brown interior bark.