Alnus glutinosa - Common Alder
Family: Betulaceae

Hear the scientific name

Alnus glutinosa is an underutilized shade tree that is excellent for wet or dry sites. European Alder has glossy dark green summer foliage, a pyramidal shape and rapid growth in youth, and ornamental fruits and catkins in winter.

Alternate common name: European Alder

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  form2 form Form

-large shade tree, doubling as an ornamental tree in youth

-maturing at 60' tall x 30' wide

-upright pyramidal growth habit in youth, becoming upright oval or open and irregular with maturity, sometimes losing its strong central leader with age, and also sometimes found in multi-trunked form

-rapid to medium growth rate

foliage2 foliage Foliage

-alternate, densely foliaged, and dark glossy green

leaf blades are 3" long x 3" wide, oval to orbicular, doubly serrated, and distinctly notched at the apex when fully expanded, with impressed veins

-autumn color is green, yellowish- green, or yellow-brown, and ornamentally ineffective

Flowers
flowers

-monoecious (separate male and female flowers on the same plant)

-clustered reddish-brown male catkins are present in winter, to about 1" long, but elongate up to 4" in Mar., swaying in the early spring winds

-miniature oval purple female flowers are barely noticeable in Mar., without any corolla but emerging with exerted pistils to accept pollen from the nearby catkins

Fruit
fruit

-small brown winged nutlet seeds are borne in green ovoid rough fruits that are about 0.5" long, changing to dark brown in autumn

-the winter persistent clusters of opened fruits (strobiles) that resemble miniature pine cones are very characteristic of Alders, and often persist into the following season

Twig
twig

-green-brown to brown and smooth

trunk Trunk

-bark is green-brown in youth, changing to brown and slightly ridged with maturity

-trees can be single leader or multi-trunked, and are strongly pyramidal in youth, but more upright oval and sometimes losing the central leader with age

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Culture

-full sun to partial sun

-prefers moist to wet soils of average fertility in full sun, but is adaptable to poor soils, dry soils, and soils of various pH

-sensitive to heat and drought

-forms a nitrogen-fixing association with microorganisms

-sensitive to branch cankers and tent caterpillars as occasional minor disease and pest problems, respectively

-low availability, in B&B form

Hardiness

-zones 3 to 7

Origin

-native to Europe, Western Asia, and Northern Africa; naturalizes along wet sites where it has escaped and self-propagated by seeds

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Assets

-wet site or dry site tolerant; an alternative to Willows and Poplars for wet and difficult sites

-rapid growth and establishment

-dark glossy green foliage that flutters in the breeze

-can also be considered an ornamental tree in youth (due to its strongly pyramidal habit, winter persistent cone-like fruits, and late winter elongated catkins)

-wood more resistant to storm damage as compared to other rapidly growing landscape trees

Liabilities

-none serious, although branch cankers and tent caterpillars occasionally occur

Function

-shade, specimen, wet site, or deciduous windbreak tree, effective in solitary, group, or linear plantings

Texture

-medium texture in foliage and when bare

-thick density in foliage and when bare

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Varieties and Cultivars - Search OSU PlantFacts for additional plants in this species

Alternates

-rapidly growing shade trees (Acer x freemanii, Betula nigra, Liquidambar styraciflua, Quercus acutissima, Zelkova serrata, etc.)

-shade trees for wet sites (Betula nigra, Celtis occidentalis, Populus deltoides, Quercus bicolor, Salix alba, Taxodium distichum, etc.)

-pyramidal trees (at least in youth) (Abies fraseri, Picea abies, Liquidambar styraciflua, Quercus palustris, Taxodium distichum, etc.)

 


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