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From Wikipedia, the free encyclopedia

Alnus serrulata (Tag Alder)
Male catkins on right,
mature female catkins left
Johnsonville, South Carolina
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Fagales
Family: Betulaceae
Genus: Alnus

About 20-30 species, see text.

Alder is the common name of a genus of flowering plants (Alnus) belonging to the birch family (Family Betulaceae). The genus comprises about 30 species of monoecious trees and shrubs, few reaching large size, distributed throughout the North Temperate Zone and in the Americas also along the Andes southwards to Argentina.



Alder leaves are deciduous (not evergreen), alternate, simple, and serrated. The flowers are catkins with elongate male catkins on the same plant as shorter female catkins, often before leaves appear; they are mainly wind-pollinated, but also visited by bees to a small extent. They differ from the birches (Betula, the other genus in the family) in that the female catkins are woody and do not disintegrate at maturity, opening to release the seeds in a similar manner to many conifer cones.

The largest species are Red Alder (A. rubra) on the west coast of North America and Black Alder (A. glutinosa), native to most of Europe and widely introduced elsewhere, both reaching over 30 m. By contrast, the widespread Green Alder (A. viridis) is rarely more than a 5 m tall shrub.

Nitrogen fixation

A sectioned root nodule.
A whole root nodule.

Alder is particularly noted for its important symbiotic relationship with Frankia alni, actinomycete filamentous nitrogen-fixing bacterium. This bacterium is found in root nodules which may be as large as a human fist, with many small lobes and light brown in appearance. The bacterium absorbs nitrogen from the air and makes it available to the tree. Alder, in turn, provides the bacterium with carbon, which it produces through photosynthesis. As a result of this mutually-beneficial relationship, alder improves the fertility of the soils where it grows, and as a pioneer species, it helps provide additional nitrogen for the successional species which follow.

Word origin

The common name alder is derived from an old Germanic root. Also found to be the translation of the Old French "verne" for alder or copse of alders. The botanic name Alnus is the equivalent Latin name. Both the Latin and the Germanic words derive from the Proto-Indo-European root el-, meaning "red" or "brown", which is also a root for the English words elk and another tree: elm, a tree distantly related to the alders. In celtic mythology , bran the blessed is associated with the alder tree "The Alder deity is considered to be Bran the Blessed, God of the Underworld. He was also known as the God of Prophecy, Arts, War and Writing. With the size of a giant, it was impossible for Bran to fit in a house or in a boat. According to medieval Christian writings, Bran the Blessed is considered to be the first British man." "ref"

Edibility and medicinal uses

Alder catkins are edible and high in protein. Although they are reported to have a bitter and unpleasant taste, they are best remembered for survival purposes. Alder wood is also commonly used to smoke various food items.

Alder bark contains the anti-inflammatory salicin which is metabolized into salicylic acid in the body.[1] Native Americans used Red Alder bark (Alnus rubra) to treat poison oak, insect bites, and skin irritations. Blackfeet Indians used an infusion made from the bark of Red Alder to treat lymphatic disorders and tuberculosis. Recent clinical studies have verified that red alder contains betulin and lupeol, compounds shown to be effective against a variety of tumors.[2]


The genus is divided into three subgenera:

Subgenus Alnus. Trees. Shoot buds stalked. Male and female catkins produced in autumn (fall) but staying closed over winter, pollinating in late winter or early spring. About 15-25 species, including:

Speckled Alder (Alnus incana subsp. rugosa) — leaves
  • Alnus incana — Grey Alder. Eurasia.
    • Alnus hirsuta (A. incana subsp. hirsuta) — Manchurian Alder. Northeastern Asia, and central Asia in mountains.
    • Alnus oblongifolia (A. incana subsp. oblongifolia) — Arizona Alder. Southwestern North America.
    • Alnus rugosa (A. incana subsp. rugosa) — Speckled Alder. Northeastern North America.
    • Alnus tenuifolia (A. incana subsp. tenuifolia) — Thinleaf or Mountain Alder. Northwestern North America.
  • Alnus japonica — Japanese Alder. Japan.
  • Alnus jorullensis — Mexican Alder. Mexico, Guatemala.
  • Alnus mandshuricaRussian Far East, China, Korea.
  • Alnus matsumuraeHonshū (Japan).
  • Alnus nepalensis — Nepalese Alder. Eastern Himalaya, southwest China.
  • Alnus orientalis — Oriental Alder. Southern Turkey, northwest Syria, Cyprus.
  • Alnus pendulaJapan, Korea.
  • Alnus rhombifolia — White Alder. Interior western North America.
  • Alnus rubra — Red Alder. West coastal North America.
Leaves of the Tag Alder
  • Alnus serrulata — Hazel alder, Tag Alder or Smooth alder. Eastern North America.
  • Alnus sieboldianaHonshū (Japan).
  • Alnus subcordata — Caucasian Alder. Caucasus, Iran.
  • Alnus trabeculosaChina, Japan.

Subgenus Clethropsis. Trees or shrubs. Shoot buds stalked. Male and female catkins produced in autumn (fall) and expanding and pollinating then. Three species:

  • Alnus formosana — Formosan Alder Taiwan
  • Alnus maritima — Seaside Alder. East coastal North America, plus disjunct population in Oklahoma.
  • Alnus nitida — Himalayan Alder. Western Himalaya.

Subgenus Alnobetula. Shrubs. Shoot buds not stalked. Male and female catkins produced in late spring (after leaves appear) and expanding and pollinating then. One to four species:

Green Alder (Alnus viridis)
  • Alnus viridis — Green Alder. Widespread:
    • Alnus viridis subsp. viridis. Eurasia.
    • Alnus viridis subsp. maximowiczii (A. maximowiczii). Japan.
    • Alnus viridis subsp. crispa (A. crispa). Northern North America.
    • Alnus viridis subsp. sinuata (A. sinuata, Sitka Alder or Slide Alder). Western North America, far northeastern Siberia.

Weed status

A. glutinosa and A. viridis are classed as environmental weeds in New Zealand.[3]

Cultural references

Alder coat of arms of Grossarl, Austria.

Alder is illustrated in the coat of arms for the Austrian town of Grossarl.


  1. ^ Ewing, Susan. The Great Alaska Nature Factbook. Portland: Alaska Northwest Books, 1996.
  2. ^ Edible and Medicinal Plants of the West, Gregory L. Tilford, ISBN 0-87842-359-1
  3. ^ Clayson, Howell (May 2008). Consolidated list of environmental weeds in New Zealand. Wellington: Department of Conservation. ISBN 978-0-478-14412-3.  

Further reading

  • Chen, Zhiduan and Li, Jianhua (2004). Phylogenetics and Biogeography of Alnus (Betulaceae) Inferred from Sequences of Nuclear Ribosomal DNA ITS Region. International Journal of Plant Sciences 165: 325–335.

External links


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

ALDER, a genus of plants (Alnus) belonging to the order Betulaceae, the best-known of which is the common alder (A. glutinosa). The genus comprises a few species of shrubs or trees, seldom reaching a large size, distributed through the North Temperate zone, and in the New World passing along the Andes southwards to Chile. The British species A. glutinosa is confined to the Old World. This tree thrives best in moist soils, has a shrubby appearance, and grows under favourable circumstances to a height of 40 or 50 ft. It is characterized by its short-stalked roundish leaves, 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 dark olive green. As with other plants growing near water it keeps its leaves longer than do trees in drier situations, and the glossy green foliage lasting after other trees have put on the red or brown of autumn renders it valuable for landscape effect. The stout cylindrical male catkins are pendulous, reddish in colour and 2 to 4 in. long; the female are smaller, less than an inch in length and reddish-brown in colour, suggesting young fir-cones. When the small winged fruits 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. 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. Furniture is sometimes made from the wood, and it supplies excellent charcoal for gunpowder. The bark is astringent; it is used for tanning and dyeing.

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Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

See also alder, and ålder


Proper noun




  1. A topographic surname for someone who lived by alder trees.


Up to date as of January 23, 2010
(Redirected to Joshua Alder article)

From Wikispecies


External links

Simple English

Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Fagales
Family: Betulaceae
Genus: Alnus

About 20-30 species, see text.

Alder is the common name for about 30 kinds of trees and shrubs of the Alnus genus. They are a part of the birch family (Betulaceae). Most of them are smaller in size. Leaves are mostly deciduous, only very few alders are evergreen.

The best known species are the Black Alder, which can be seen throughout Europe. The largest is probably the Red Alder, native to North America. It reaches about 32-35 metres in height. The widespread Green Alder is a shrub, rarely more than 5m high.

Alder is a preferred tree for bees, especially in spring. It is also used to make charcoal.

Look up Alnus in Wikispecies, a directory of species



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