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Alnus glutinosa
Trees in native environment, Marburg, Germany
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Fagales
Family:	Betulaceae
Genus:	Alnus
Subgenus:	Alnus
Species:	A. glutinosa
Binomial name
Alnus glutinosa L.

Alnus glutinosa (English: Black Alder, European Alder or Common Alder) is an alder native to most of Europe, including all of the British Isles and Fennoscandia and locally in southwest Asia.^[1][2]

Foliage

Alnus glutinosa is a tree that thrives in moist soils, and grows under favourable circumstances to a height of 20–30 m, exceptionally up to 37 m^[3], though often less. It is characterized by its 5–10 cm short-stalked rounded leaves 6–12 cm long, becoming wedge-shaped at the base and with a slightly toothed margin. When young they are somewhat glutinous, whence the specific name, becoming later a glossy dark green. As with some other plants growing near water it keeps its leaves longer than do trees in drier situations, the glossy green foliage lasting after other trees have put on the red or brown of autumn, which renders it valuable for landscape effect. As the Latin name glutinosa implies, the buds and young leaves are slightly sticky with a resinous gum.^[1][4][5][6]

Male (left) and female inflorescences

There are four subspecies:

• Alnus glutinosa subsp. glutinosa - Europe
• Alnus glutinosa subsp. barbata - Northern Anatolia (Rize,Trabzon, Artvin); northern Iran
• Alnus glutinosa subsp. antitaurica - Southern Anatolia, rare
• Alnus glutinosa subsp. betuloides - Eastern Anatolia.

The species is monoecious. Flowers are wind-pollinated catkins: the slender cylindrical male catkins are pendulous, reddish in colour and 5–10 cm long; the female are smaller, 2 cm in length and dark brown to black in colour, hard, somewhat woody, and superficially similar to some conifer cones. When the small winged seeds have been scattered the ripe, woody, blackish cones remain, often lasting through the winter. The alder is readily propagated by seeds, but throws up root suckers abundantly. ^[1][4]

Important ecological relationships

Alnus glutinosa is most noted for the symbiotic relationship with the bacterium Frankia alni, which forms nodules on the tree's roots. This nitrogen-fixing bacterium absorbs nitrogen from the environment and fixes it into a form available to the tree. In return, the bacterium receives carbon which is produced by the tree through photosynthesis. This relationship, which improves the fertility of the soil environment, has established A. glutinosa as an important pioneer species in ecological succession.

A. glutinosa is also a host to a wide variety of moss and lichen. Some common species found on A. glutinosa include: Tree Lungwort (Lobaria pulmonaria), Stenocybe pullatula, and Menneguzzia terebrata.

Diseases

Alnus glutinosa is susceptible to Phytophthora alni, a recently evolved species of Phytophthora probably of hybrid origin. This is causing extensive mortality in some parts of Europe.^[7]

Uses

It is important as coppice-wood on marshy ground. The wood is soft, white when first cut and turning to pale red; the knots are beautifully mottled. Under water the wood is very durable, and it is therefore used for piles. The supports of the Rialto at Venice, and many buildings at Amsterdam, are of Alder wood. It is also the traditional wood burnt to produce smoked fish and other smoked foods, though in some areas other woods are more often used now. Furniture is sometimes made from the wood, as were clogs, and it supplies excellent charcoal for gunpowder. The bark is astringent; it is used for tanning and dyeing.^[5] Alnus glutinosa is also cultivated and locally naturalised in eastern North America.^[1]

Weed status

A. glutinosa is classed as an environmental weed in New Zealand.^[8]

Details of Alder structure and galls

Alder carr in Germany	Trees in winter, Germany	Buds	Bark
Alder Tongue Gall Taphrina amentorum	Detail - Alder Tongue Gall

References

From Wikispecies

subsp. glutinosa

Taxonavigation

Classification System: APG II (down to family level)

Main Page
Cladus: Eukaryota
Regnum: Plantae
Cladus: Angiospermae
Cladus: Eudicots
Cladus: core eudicots
Cladus: Rosids
Cladus: Eurosids I
Ordo: Fagales
Familia: Betulaceae
Subfamiliae: Betuloideae
Genus: Alnus
Subgenus: Alnus subg. Alnus
Species: Alnus glutinosa
Subspecies: A. g. subsp.  antitaurica - A. g. subsp.  barbata - A. g. subsp.  betuloides - A. g. subsp.  glutinosa

Name

Alnus glutinosa (L.) Gaertn.

References

USDA, NRCS. 2006. The PLANTS Database, 6 March 2006 (http://plants.usda.gov). Data compiled from various sources by Mark W. Skinner. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Vernacular names

For more multimedia, look at Alnus glutinosa on Wikimedia Commons.