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

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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.

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 a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

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''). It contains many, usually unisexual flowers, arra ...

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'', native to Europe and widely naturalized *''Ilex verticillata ''Ilex verticillata'', the winterberry, is a species of holly native to eastern North America in ...

(''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 continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and northwestern

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

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

Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...

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

and the

Caucasus The Caucasus () or Caucasia (), is a region spanning Eastern Europe and Western Asia. It is situated between the Black Sea and the Caspian Sea, comprising parts of Southern Russia, Georgia, Armenia, and Azerbaijan. The Caucasus Mountains, i ...

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

Northeast Asia Northeast Asia or Northeastern Asia is a geographical Subregion#Asia, subregion of Asia. Its northeastern landmass and islands are bounded by the Pacific Ocean, North Pacific Ocean. The term Northeast Asia was popularized during the 1930s by Ame ...

and

Central Asia Central Asia is a region of Asia consisting of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. The countries as a group are also colloquially referred to as the "-stans" as all have names ending with the Persian language, Pers ...

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

* ''Alnus incana'' subsp. ''oblongifolia'' (=''

Alnus oblongifolia ''Alnus oblongifolia'' (Arizona alder) is a large alder growing up to , from the southwestern United States and northern Sonora, Mexico. It grows across Arizona into western New Mexico mountain ranges. In central Arizona its range extends across ...

''); 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 su ...

of southwestern

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, in

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

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

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

below the

tree line The tree line is the edge of a habitat at which trees are capable of growing and beyond which they are not. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually low ...

, and the

Northeastern United States The Northeastern United States (also referred to as the Northeast, the East Coast, or the American Northeast) is List of regions of the United States, census regions United States Census Bureau. Located on the East Coast of the United States, ...

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

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

and

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

; the roots have

nitrogen-fixing Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiological nitrogen fixation, abiologically in chemical industry, chemical industries. Biological nitrogen ...

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 (, ) 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. Alluvium is also sometimes called alluvial deposit. Alluvium is ...

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 ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

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 ...

s. In the

boreal forest Taiga or tayga ( ; , ), also known as boreal forest or snow forest, is a biome characterized by pinophyta, coniferous forests consisting mostly of pines, spruces, and larches. The taiga, or boreal forest, is the world's largest land biome. I ...

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 Newfoundland and Labrador and is tha ...

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 Pedunculagin is an ellagitannin. It is formed from casuarictin via the loss of a gallate group. Natural occurrence Pedunculagin is found in plants in orders in the clade Rosidae. It can be found the pericarp of pomegranates (''Punica granatum ...

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 ...

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

. It is sometimes used in

afforestation Afforestation is the establishment of a forest or stand of trees in an area where there was no recent tree cover. There are three types of afforestation: natural Regeneration (biology), regeneration, agroforestry and Tree plantation, tree plan ...

and

agroforestry Agroforestry (also known as agro-sylviculture or forest farming) is a land use management system that integrates trees with crops or pasture. It combines agricultural and forestry technologies. As a polyculture system, an agroforestry system c ...

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

nitrogen fixing Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiologically in chemical industries. Biological nitrogen fixation or ''diazotrophy'' is catalyzed by en ...

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 (; formerly spelled ''Zuñi'') are Native American Pueblo peoples native to the Zuni River valley. The Zuni people today are federally recognized as the Zuni Tribe of the Zuni Reservation, New Mexico, and most live in the Pueblo o ...

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

Ho-Chunk The Ho-Chunk, also known as Hocąk, Hoocągra, or Winnebago are a Siouan languages, Siouan-speaking Native Americans in the United States, Native American people whose historic territory includes parts of Wisconsin, Minnesota, Iowa, and Illinois ...

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