''Alnus incana'', the grey alder or speckled alder, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

of multi-stemmed, shrubby tree in the birch family, with a wide range across the cooler parts of the Northern Hemisphere. Tolerant of wetter soils, it can slowly spread with runners and is a common sight in swamps and wetlands. It is easily distinguished by its small cones, speckled bark and broad leaves.

Description

It is a small- to medium-sized tree tall with smooth grey bark even in old age, its life span being a maximum of 60 to 100 years. The

leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...

are matte green, ovoid, long and broad. The flowers are

catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in '' Salix''). They contain many, usually unisexual flowers, arrang ...

s, appearing early in spring before the leaves emerge, the male catkins pendulous and long, the female catkins long and one cm broad when mature in late autumn. The seeds are small, long, and light brown with a narrow encircling wing. The grey alder has a shallow root system, and is marked not only by vigorous production of stump suckers, but also by root suckers, especially in the northern parts of its range. The wood resembles that of the

black alder Black alder is a common name for several plants and may refer to: *''Alnus glutinosa ''Alnus glutinosa'', the common alder, black alder, European alder, European black alder, or just alder, is a species of tree in the family Betulaceae, nativ ...

(''Alnus glutinosa''), but is somewhat paler and of little economic value.

Subspecies

There are four to six subspecies, some treated as separate species by some authors: * ''Alnus incana'' subsp. ''incana''; grey alder — Northern

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

and northwestern

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

, and central and southern Europe in mountains, mainly in the regions of the

Alps The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...

Carpathians The Carpathian Mountains or Carpathians () are a range of mountains forming an arc across Central Europe. Roughly long, it is the third-longest European mountain range after the Urals at and the Scandinavian Mountains at . The range stretche ...

and the

Caucasus The Caucasus () or Caucasia (), is a region between the Black Sea and the Caspian Sea, mainly comprising Armenia, Azerbaijan, Georgia, and parts of Southern Russia. The Caucasus Mountains, including the Greater Caucasus range, have historica ...

* ''Alnus incana'' subsp. ''hirsuta'' (=''A. hirsuta'' ); Manchurian alder — In mountains of

Northeast Asia Northeast Asia or Northeastern Asia is a geographical subregion of Asia; its northeastern landmass and islands are bounded by the Pacific Ocean. The term Northeast Asia was popularized during the 1930s by American historian and political scient ...

and

Central Asia Central Asia, also known as Middle Asia, is a region of Asia that stretches from the Caspian Sea in the west to western China and Mongolia in the east, and from Afghanistan and Iran in the south to Russia in the north. It includes the fo ...

* ''Alnus incana'' subsp. ''kolaensis'' — Subarctic northeast

* ''Alnus incana'' subsp. ''oblongifolia'' (='' Alnus oblongifolia''); Arizona alder —

Madrean Sky Islands The Madrean Sky Islands are enclaves of Madrean pine–oak woodlands, found at higher elevations in a complex of small mountain ranges in southern and southeastern Arizona, southwestern New Mexico, and northwestern Mexico. The sky islands are s ...

of southwestern

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

, in

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

, and Northwestern Mexico * ''Alnus incana'' subsp. ''rugosa'' (=''A. rugosa'' ); speckled alder — Much of

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...

below the

tree line The tree line is the edge of the habitat at which trees are capable of growing. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually cold temperatures, extreme snow ...

, and the

Northeastern United States The Northeastern United States, also referred to as the Northeast, the East Coast, or the American Northeast, is a geographic region of the United States. It is located on the Atlantic coast of North America, with Canada to its north, the Southe ...

* ''Alnus incana'' subsp. ''tenuifolia'' (=''A. tenuifolia'' ); mountain alder, or thinleaf alder — Western North America, including

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

and

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...

; the roots have nitrogen-fixing nodules. Alnus incana ssp incana range map 1.png, ''A. incana'' subsp. ''incana'' range Alnus incana ssp rugosa range map 1.png, ''A. incana'' subsp. ''rugosa'' range Alnus incana ssp tenuifolia range map 1.png, ''A. incana'' subsp. ''tenuifolia'' range

Ecology

''Alnus incana'' is a light-demanding, fast-growing tree that grows well on poorer soils. In central Europe, it is a colonist of

alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. ...

land alongside mountain brooks and streams, occurring at elevations up to . However, it does not require moist soil, and will also colonize screes and shallow stony slopes. In the northern part of its range, it is a common tree species at sea level in forests, abandoned fields and on lakeshores. Several species of

Lepidoptera Lepidoptera ( ) is an order of insects that includes butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 families and 46 superfamilies, 10 percent of the total described speci ...

use grey alder as a food plant for their

caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sy ...

s. In the

boreal forest Taiga (; rus, тайга́, p=tɐjˈɡa; relates to Mongolic and Turkic languages), generally referred to in North America as a boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruc ...

area of Canada, ''A. incana'' is often associated with

black spruce ''Picea mariana'', the black spruce, is a North American species of spruce tree in the pine family. It is widespread across Canada, found in all 10 provinces and all 3 territories. It is the official tree of the province of Newfoundland and Lab ...

in the forest type termed black spruce–speckled alder. The larvae of the alder woolly sawfly sometimes cause considerable defoliation to the grey alder. ''A. rugosa'' provides cover for wildlife, is browsed by deer and moose, and the seeds are eaten by birds.

Chemistry

Pedunculagin is an ellagitannin found in the Manchurian alder (''A. hirsuta var. microphylla'').

Uses

The tree is cultivated in parks and gardens. The cultivar 'Aurea', with green-gold leaves, has gained the

Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr (Nor ...

Award of Garden Merit The Award of Garden Merit (AGM) is a long-established annual award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. History The Award of Garden Merit ...

. It is sometimes used in

afforestation Afforestation is the establishment of a forest or stand of trees ( forestation) in an area where there was no previous tree cover. Many government and non-governmental organizations directly engage in afforestation programs to create forests ...

and

agroforestry Agroforestry is a land use management system in which trees or shrubs are grown around or among crops or pastureland. Trees produce a wide range of useful and marketable products from fruits/nuts, medicines, wood products, etc. This intentional ...

in non-fertile or wet soils which it enriches by means of

nitrogen fixing Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmo ...

bacteria in its root nodules. Alder is an excellent tree for coppicing and pollarding. Its cut branches may be fed to browsing livestock such as cows and goats, then used for kindling, firewood, or light construction - while root systems fertilize adjacent agricultural plots via nitrogen fixation. The

Zuni people The Zuni ( zun, A:shiwi; formerly spelled ''Zuñi'') are Native American Pueblo peoples native to the Zuni River valley. The Zuni are a Federally recognized tribe and most live in the Pueblo of Zuni on the Zuni River, a tributary of the Li ...

use the bark of the ''tenuifolia'' subspecies to dye deerskin reddish brown. The

Ho-Chunk people The Ho-Chunk, also known as Hoocągra or Winnebago (referred to as ''Hotúŋe'' in the neighboring indigenous Iowa-Otoe language), are a Siouan-speaking Native American people whose historic territory includes parts of Wisconsin, Minnesota, Iow ...

eat the bark of the ''rugosa'' subspecies when their stomachs are "sour" or upset. Its wood and bark are used in smoking meat, particularly fish and duck.

Description

Subspecies

Ecology

Chemistry

Uses

References

Further reading