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Alders are
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
s comprising the genus ''Alnus'' in the birch family
Betulaceae Betulaceae, the birch family, includes six genera of deciduous nut-bearing trees and shrubs, including the birches, alders, hazels, hornbeams, hazel-hornbeam, and hop-hornbeams numbering a total of 167 species. They are mostly natives of the t ...
. The genus comprises about 35 species of
monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is conne ...
trees and
shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...
s, a few reaching a large size, distributed throughout the
north temperate zone In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
with a few species extending into
Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
, as well as the northern and southern
Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
.


Description

With a few exceptions, alders are
deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...
, and the leaves are alternate, simple, and
serrated Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied pr ...
. The
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s 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, arranged cl ...
s with elongate male catkins on the same plant as shorter female catkins, often before leaves appear; they are mainly
wind-pollinated Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes. Other common anemophilous plan ...
, but also visited by bees to a small extent. These trees differ from the
birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus ''Betula'' contains 30 ...
es (''Betula'', another 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 cone A conifer cone (in formal botany, botanical usage: strobilus, plural strobili) is a seed-bearing organ on gymnosperm plants. It is usually woody, ovoid to globular, including scales and bracts arranged around a central axis, especially in con ...
s. The largest species are
red alder ''Alnus rubra'', the red alder, is a deciduous broadleaf tree native to western North America (Alaska, Yukon, British Columbia, Washington, Oregon, California, Idaho and Montana). Description Red alder is the largest species of alder in North A ...
(''A. rubra'') on the west coast of North America, and
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 ...
(''A. glutinosa''),
native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entert ...
to most of Europe and widely introduced elsewhere, both reaching over . By contrast, the widespread ''
Alnus alnobetula ''Alnus alnobetula'' is a common tree widespread across much of Europe, Asia, and North America. Many sources refer to it as ''Alnus viridis'', the green alder, but botanically this is considered an illegitimate name synonymous with ''Alnus alnob ...
'' (green alder) is rarely more than a shrub.


Phylogeny


Classification

The genus is divided into three subgenera:


Subgenus ''Alnus''

Trees with stalked shoot buds, male and female catkins produced in autumn (fall) but stay closed over winter, pollinating in late winter or early spring, about 15–25 species, including: * ''
Alnus acuminata ''Alnus acuminata'' is a species of deciduous tree in the Betulaceae family. It is found in montane forests from central Mexico to Argentina.Zuloaga, F. O., O. N. Morrone, M. J. Belgrano, C. Marticorena & E. Marchesi. (eds.) 2008. Catálogo de la ...
'' ** subsp. ''acuminata'' ** subsp. ''arguta'' ** subsp. ''glabrata'' * ''
Alnus cordata ''Alnus cordata'', the Italian alder, is a tree or shrub species belonging to the family Betulaceae, and native to the southern Apennine Mountains (Campania, Basilicata and Calabria, mainly on western mountain sides) and the north-eastern mountai ...
'' * ''
Alnus cremastogyne ''Alnus cremastogyne'' is a species of flowering plant in the genus ''Alnus''. J. Linn. Soc., Bot. 26: 499 1890. It is found in China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's m ...
'' * ''
Alnus firma ''Alnus firma'' is a species of Alnus from Japan. References External links * * firma Firma may refer to: * Firma, Missouri, a ghost town in the United States * Firma (supporter group), a Serbian football fan club *''Firma'', a monthly ...
'' * ''
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, native to most of Europe, southwest Asia and northern Africa. It thrives in wet locations whe ...
'' ** subsp. ''barbata'' ** subsp. ''glutinosa'' ** subsp. ''incisa'' ** subsp. ''laciniata'' * ''
Alnus hirsuta ''Alnus incana'', the grey alder or speckled alder, is a species 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 ...
'' * ''
Alnus incana ''Alnus incana'', the grey alder or speckled alder, is a species 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 ...
'' ** subsp. ''incana'' ** subsp. ''kolaensis'' ** subsp. ''rugosa'' ** subsp. ''tenuifolia'' * ''
Alnus japonica ''Alnus japonica'', known as Japanese alder, is a species of Alnus Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a larg ...
'' * ''
Alnus jorullensis ''Alnus jorullensis'', commonly known as Mexican alder, is an evergreen or semi-evergreen alder, native to eastern and southern Mexico, Guatemala and Honduras. Although previously reported from the Andes, further collections showed these to be th ...
'' ** subsp. ''lutea'' ** subsp. ''jorullensis'' * ''
Alnus lusitanica Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...
'' * '' Alnus matsumurae'' * ''
Alnus nepalensis ''Alnus nepalensis'' is a large alder tree found in the subtropical highlands of the Himalayas. The tree is called Utis in Nepali and Nepalese alder in English. It is used in land reclamation, as firewood and for making charcoal. Description ...
'' * ''
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 ...
'' * ''
Alnus orientalis ''Alnus orientalis'', the Oriental alder, is a deciduous, short-lived species of alder (''Alnus''). It grows up to 50 meters high, and is native to Cyprus and Cilicia Cilicia (); el, Κιλικία, ''Kilikía''; Middle Persian: ''klkyʾy'' ...
'' * ''
Alnus rhombifolia ''Alnus rhombifolia'', the white alder, is an alder tree native to western North America, from British Columbia and Washington east to western Montana, southeast to the Sierra Nevada, and south through the Peninsular Ranges and Colorado Desert oa ...
'' * ''
Alnus rohlenae Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...
'' * ''
Alnus rubra ''Alnus rubra'', the red alder, is a deciduous broadleaf tree native to western North America (Alaska, Yukon, British Columbia, Washington, Oregon, California, Idaho and Montana). Description Red alder is the largest species of alder in North A ...
'' * ''
Alnus serrulata ''Alnus serrulata'', the hazel alder or smooth alder, is a thicket-forming shrub in the family Betulaceae. It is native to eastern North America and can be found from western Nova Scotia and southern New Brunswick south to Florida and Texas. D ...
'' * ''
Alnus subcordata ''Alnus subcordata'', the Caucasian alder, is a species in the family Betulaceae, native to Hyrcanian forests of Iran and the Caucasus. It is closely related to the Italian alder (''A. cordata'') and ''Alnus orientalis''. It is a deciduous tre ...
'' * ''
Alnus tenuifolia ''Alnus incana'', the grey alder or speckled alder, is a species 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 ...
'' * ''
Alnus trabeculosa Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...
''


Subgenus ''Clethropsis''

Trees or shrubs with stalked shoot buds, male and female catkins produced in autumn (fall) and expanding and pollinating then, three species: * ''
Alnus formosana ''Alnus formosana'', the Formosan alder, is a species of alder endemic to Taiwan. It is a medium-sized tree, up to in height and in trunk diameter. Description The formosan alder is a trees up to 20 meters in height with dark gray-brown bark ...
'' * ''
Alnus maritima ''Alnus maritima'', the seaside alder or brook alder, is a species of shrub or small tree in the family Betulaceae. ''Alnus maritima'' is endemic to the United States, and is found naturally in three disjunct populations in Oklahoma, Georgia, ...
'' * ''
Alnus nitida ''Alnus nitida'', the west Himalayan alder, is a species in the genus ''Alnus'', native to Pakistan, the western Himalayas, and Nepal. It is a tree reaching 20 to 25m, preferring to live along the banks of rivers. It is used locally for timber an ...
''


Subgenus ''Alnobetula''

Shrubs with shoot buds not stalked, male and female catkins produced in late spring (after leaves appear) and expanding and pollinating then, one to four species: * ''
Alnus alnobetula ''Alnus alnobetula'' is a common tree widespread across much of Europe, Asia, and North America. Many sources refer to it as ''Alnus viridis'', the green alder, but botanically this is considered an illegitimate name synonymous with ''Alnus alnob ...
'' (synonym-''Alnus viridis'') ** subsp. ''alnobetula'' ** subsp. ''crispa'' ** subsp. ''fruticosa'' ** subsp. ''sinuata'' ** subsp. ''suaveolens'' * ''
Alnus firma ''Alnus firma'' is a species of Alnus from Japan. References External links * * firma Firma may refer to: * Firma, Missouri, a ghost town in the United States * Firma (supporter group), a Serbian football fan club *''Firma'', a monthly ...
'' * ''
Alnus mandshurica ''Alnus mandshurica'' is a species of Alnus Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed t ...
'' * '' Alnus maximowiczii'' * ''
Alnus pendula Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...
'' * ''
Alnus sieboldiana ''Alnus sieboldiana'' (オオバヤシャブシ in Japanese) is an alder species found on the islands of Honshū, Shikoku, and Suwanose-jima in Japan. ''A. sieboldiana'' contains the ellagitannins alnusiin, tellimagrandin I, pedunculagin, ...
''


Not assigned to a subgenus

* ''
Alnus fauriei Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...
'' * ''
Alnus ferdinandi-coburgii Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...
'' * ''
Alnus glutipes Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...
'' * ''
Alnus hakkodensis Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the Temperate climate, north temperate z ...
'' * '' Alnus henryi'' * ''
Alnus lanata Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the Temperate climate, north temperate z ...
'' * '' Alnus mairei'' * ''
Alnus paniculata Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...
'' * ''
Alnus serrulatoides Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the Temperate climate, north temperate z ...
'' * ''
Alnus vermicularis Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...
''


Species names with uncertain taxonomic status

The status of the following species is unresolved: * ''Alnus balatonialis'' * ''Alnus cuneata'' * ''Alnus dimitrovii'' * ''Alnus djavanshirii'' – Iran * ''Alnus dolichocarpa'' – Iran * ''Alnus figerti'' * ''Alnus frangula'' * ''Alnus gigantea'' * ''Alnus glandulosa'' * ''Alnus henedae'' * ''Alnus hybrida'' * ''Alnus laciniata'' * ''Alnus lobata'' * ''Alnus microphylla'' * ''Alnus obtusifolia'' * ''Alnus oxyacantha'' * ''Alnus subrotunda'' * ''Alnus vilmoriana'' * ''Alnus washingtonia''


Hybrids

The following hybrids have been described: * ''
Alnus × elliptica Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...
'' (''A. cordata'' × ''A. glutinosa'') * ''
Alnus × fallacina Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...
'' (''A. incana'' subsp. ''rugosa'' × ''A. serrulata'') * ''
Alnus × hanedae Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the Temperate climate, north temperate z ...
'' (''A. firma'' × ''A. sieboldiana'') * ''
Alnus × hosoii Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the Temperate climate, north temperate z ...
'' (''A. maximowiczii'' × ''A. pendula'') * ''
Alnus × mayrii Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...
'' (''A. hirsuta'' × ''A. japonica'') * ''
Alnus × peculiaris Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...
'' (''A. firma'' × ''A. pendula'') * ''
Alnus × pubescens Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few spec ...
'' (''A. glutinosa'' × ''A. incana'') * ''
Alnus × suginoi Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the Temperate climate, north temperate z ...
'' The status of the following hybrids is unresolved: * ''Alnus'' × ''aschersoniana'' * ''Alnus'' × ''koehnei'' * ''Alnus'' × ''ljungeri'' * ''Alnus'' × ''purpusii'' * ''Alnus'' × ''silesiaca'' * ''Alnus'' × ''spaethii'' (''A. japonica'' × ''A. subcordata'')


Fossil record

The oldest fossil pollen that can be identified as ''Alnus'' is from northern
Bohemia Bohemia ( ; cs, Čechy ; ; hsb, Čěska; szl, Czechy) is the westernmost and largest historical region of the Czech Republic. Bohemia can also refer to a wider area consisting of the historical Lands of the Bohemian Crown ruled by the Bohem ...
, dating to the late
Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...
, around 58 million years ago. * †'' Alnus fairi'' - Miocene; Western North America * ''
Alnus heterodonta ''Alnus heterodonta'' is an extinct species of alder from the early Oligocene Bridge Creek floras of Central Oregon References Oligocene plants heterodonta Heteroconchia is a taxonomic infraclass of saltwater clams, marine bivalve mo ...
'' – Oligocene; Fossil, Oregon * †'' Alnus hollandiana'' - Miocene; Western North America * †'' Alnus largei'' - Miocene; Western North America * †''
Alnus parvifolia ''Alnus parvifolia'' is an extinct species of flowering plant in the family Betulaceae related to the modern birches. The species is known from fossil leaves and possible fruits found in early Eocene sites of northern Washington (state), Washing ...
'' - Ypresian;
Okanagan Highlands The Okanagan Highland is an elevated hilly plateau area in British Columbia, Canada, and the U.S. state of Washington (where it is spelled Okanogan Highlands). Rounded mountains with elevations up to above sea level and deep, narrow valleys are ...
* †'' Alnus relatus'' - Miocene; Western North America


Etymology

The common name ''alder'' evolved from the Old English word ''alor'', which in turn is derived from
Proto-Germanic Proto-Germanic (abbreviated PGmc; also called Common Germanic) is the reconstructed proto-language of the Germanic branch of the Indo-European languages. Proto-Germanic eventually developed from pre-Proto-Germanic into three Germanic branc ...
root ''aliso''. The generic name ''Alnus'' is the equivalent
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
name, from whence French ''aulne'' and Spanish ''Alamo'' (Spanish term for " poplar").


Ecology

Alders are commonly found near streams, rivers, and wetlands. Sometimes where the prevalence of alders is particularly prominent these are called
alder carr An alder carr is a particular type of carr, i.e. waterlogged wooded terrain populated with alder trees. Examples * Alder Carr, Hildersham * Alderfen Broad * Fawley Ford on the Beaulieu River * Biebrza National Park * Fen Alder Carr * Harston Woo ...
s. In the
Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...
of North America, the white alder (''Alnus rhombifolia'') unlike other northwest alders, has an affinity for warm, dry climates, where it grows along watercourses, such as along the lower
Columbia River The Columbia River (Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, C ...
east of the Cascades and the Snake River, including Hells Canyon. Alder leaves and sometimes catkins are used as food by numerous butterflies and moths. ''A. glutinosa'' and ''A. viridis'' are classed as environmental weeds in New Zealand. Alder leaves and especially the roots are important to the ecosystem because they enrich the soil with nitrogen and other nutrients.


Nitrogen fixation and succession of woodland species

Alder is particularly noted for its important
symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
relationship with ''
Frankia alni ''Frankia alni'' is a Gram-positive species of actinomycete filamentous bacterium that lives in symbiosis with actinorhizal plants in the genus ''Alnus''. It is a nitrogen-fixing bacterium and forms nodules on the roots of alder trees. Distrib ...
'', an
actinomycete The Actinomycetales is an order of Actinomycetota. A member of the order is often called an actinomycete. Actinomycetales are generally gram-positive and anaerobic and have mycelia in a filamentous and branching growth pattern. Some actinomycete ...
,
filamentous The word filament, which is descended from Latin ''filum'' meaning " thread", is used in English for a variety of thread-like structures, including: Astronomy * Galaxy filament, the largest known cosmic structures in the universe * Solar filament ...
, nitrogen-fixing
bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
. This bacterium is found in
root nodule Root nodules are found on the roots of plants, primarily legumes, that form a symbiosis with nitrogen-fixing bacteria. Under nitrogen-limiting conditions, capable plants form a symbiotic relationship with a host-specific strain of bacteria known a ...
s, which may be as large as a human fist, with many small lobes, and light brown in colour. The bacterium absorbs
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
from the air and makes it available to the tree. Alder, in turn, provides the bacterium with
sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...
s, which it produces through
photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
. As a result of this mutually beneficial relationship, alder improves the fertility of the soil where it grows, and as a
pioneer species Pioneer species are hardy species that are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by wildfire. Pioneer flora Some lichens grow on rocks without soil, so m ...
, it helps provide additional nitrogen for the successional species to follow. Because of its abundance, red alder delivers large amounts of nitrogen to enrich forest soils. Red alder stands have been found to supply between of nitrogen annually to the soil. From Alaska to Oregon, ''Alnus viridis'' subsp. ''sinuata'' (''A. sinuata'', Sitka Alder or Slide Alder), characteristically pioneer fresh, gravelly sites at the foot of retreating glaciers. Studies show that Sitka alder, a more shrubby variety of alder, adds nitrogen to the soil at an average rate of per year, helping convert the sterile glacial terrain to soil capable of supporting a conifer forest. Alders are common among the first species to colonize disturbed areas from floods, windstorms, fires, landslides, etc. Alder groves often serve as natural firebreaks since these broad-leaved trees are much less flammable than conifers. Their foliage and
leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that have fallen to the ground. This detritus or dead organic material and its constituent ...
does not carry a fire well, and their thin bark is sufficiently resistant to protect them from light surface fires. In addition, the light weight of alder seedsnumbering allows for easy dispersal by the wind. Although it outgrows
coastal Douglas-fir ''Pseudotsuga menziesii'' var. ''menziesii'', commonly known as Coast Douglas-fir, Pacific Douglas-fir, Oregon pine, or Douglas spruce, is an evergreen conifer native to western North America from west-central British Columbia, Canada southward ...
for the first 25 years, it is very shade intolerant and seldom lives more than 100 years. Red alder is the Pacific Northwest's largest alder and the most plentiful and commercially important broad-leaved tree in the coastal Northwest. Groves of red alder in diameter intermingle with young Douglas-fir forests west of the Cascades, attaining a maximum height of in about sixty years and then are afflicted by
heart rot 300px, The bracket fungus '' Fistulina hepatica'' is one of many that cause heart rot. In trees, heart rot is a fungal disease that causes the decay of wood at the center of the trunk and branches. Fungi enter the tree through wounds in the bark ...
. Alders largely help create conditions favorable for giant conifers that replace them. An alder root nodule gall.JPG, alt=An alder root nodule, Whole root nodule A sectioned alder root nodule gall.JPG, alt=A sectioned alder root nodule, Sectioned root nodules


Parasites

Alder roots are parasitized by northern groundcone.


Uses

The catkins of some alder species have a degree of edibility, and may be rich in protein. Reported to have a bitter and unpleasant taste, they are more useful for survival purposes. The wood of certain alder species is often used to smoke various food items such as
coffee Coffee is a drink prepared from roasted coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulant, stimulating effect on humans, primarily due to its caffeine content. It is the most popular hot drink in the world. S ...
,
salmon Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...
, and other seafood. Most of the
pilings A deep foundation is a type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of depths. A pile or piling is a vertical structural element ...
that form the foundation of
Venice Venice ( ; it, Venezia ; vec, Venesia or ) is a city in northeastern Italy and the capital of the Veneto Regions of Italy, region. It is built on a group of 118 small islands that are separated by canals and linked by over 400  ...
were made from alder trees. Alder bark contains the anti-inflammatory
salicin Salicin is an alcoholic β-glucoside. Salicin is produced in (and named after) willow (''Salix'') bark. It is a biosynthetic precursor to salicylaldehyde. Medicinal aspects Salicin is found in the bark of and leaves of willows, poplars and va ...
, which is metabolized into
salicylic acid Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the EPA Toxic Substance ...
in the body. Some Native American cultures use red alder bark (''
Alnus rubra ''Alnus rubra'', the red alder, is a deciduous broadleaf tree native to western North America (Alaska, Yukon, British Columbia, Washington, Oregon, California, Idaho and Montana). Description Red alder is the largest species of alder in North A ...
'') to treat poison oak, insect bites, and skin irritations. Blackfeet Indians have traditionally used an infusion made from the bark of red alder to treat lymphatic disorders and
tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in ...
. Recent clinical studies have verified that red alder contains
betulin Betulin is an abundant, naturally occurring triterpene. It is commonly isolated from the bark of birch trees. It forms up to 30% of the dry weight of silver birch bark. It is also found in birch sap. '' Inonotus obliquus'' and red alder also co ...
and
lupeol Lupeol is a pharmacologically active pentacyclic triterpenoid. It has several potential medicinal properties, like anticancer and anti-inflammatory activity. Natural occurrences Lupeol is found in a variety of plants, including mango, '' Acaci ...
, compounds shown to be effective against a variety of tumors. The inner bark of the alder, as well as
red osier dogwood ''Cornus sericea'', the red osier or red-osier dogwood, is a species of flowering plant in the family Cornaceae, native to much of North America. It has sometimes been considered a synonym of the Asian species '' Cornus alba''. Other names inclu ...
, or
chokecherry ''Prunus virginiana'', commonly called bitter-berry, chokecherry, Virginia bird cherry, and western chokecherry (also black chokecherry for ''P. virginiana'' var. ''demissa''), is a species of bird cherry (''Prunus'' subgenus ''Padus'') nat ...
, is used by some
Indigenous peoples of the Americas The Indigenous peoples of the Americas are the inhabitants of the Americas before the arrival of the European settlers in the 15th century, and the ethnic groups who now identify themselves with those peoples. Many Indigenous peoples of the A ...
in smoking mixtures, known as ''kinnikinnick'', to improve the taste of the
bearberry Bearberries (indigenous kinnickinnick) are three species of dwarf shrubs in the genus ''Arctostaphylos''. Unlike the other species of ''Arctostaphylos'' (see manzanita), they are adapted to Arctic and Subarctic climates, and have a circumpolar d ...
leaf. Alder is illustrated in the coat of arms for the Austrian town of
Grossarl Grossarl (Großarl) is a market town in the St. Johann im Pongau district in the state of Salzburg in western central Austria. The valley Grossarltal got its name from Grossarl. Geography Location The market town is located in the Grossarl V ...
. Electric guitars, most notably those manufactured by the
Fender Musical Instruments Corporation The Fender Musical Instruments Corporation (FMIC, or simply Fender) is an American manufacturer of instruments and amplifiers. Fender produces acoustic guitars, bass amplifiers and public address equipment, however it is best known for its ...
, have been built with alder bodies since the 1950s. Alder is appreciated for its tone that is claimed to be tight and evenly balanced, especially when compared to mahogany, and has been adopted by many electric guitar manufacturers. As a
hardwood Hardwood is wood from dicot trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen. Hardwood (which comes from ...
, alder is used in making furniture, cabinets, and other woodworking products. Alder bark and wood (like
oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...
and
sweet chestnut ''Castanea sativa'', the sweet chestnut, Spanish chestnut or just chestnut, is a species of tree in the family Fagaceae, native to Southern Europe and Asia Minor, and widely cultivated throughout the temperate world. A substantial, long-lived ...
) contain
tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'', ...
and are traditionally used to tan leather. A red dye can also be extracted from the outer bark, and a yellow dye from the inner bark.


Culture

Ermanno Olmi Ermanno Olmi (24 July 1931 – 7 May 2018)Lane, John Francis (May 7, 2018).Ermanno Olmi obituary. ''The Guardian''. theguardian.com. Retrieved 11 May 2018. was an Italian film director and screenwriter. Biography Olmi was born to a Catholic ...
's movie ''
The Tree of Wooden Clogs ''The Tree of Wooden Clogs'' () is a 1978 Italian film written and directed by Ermanno Olmi. The film concerns Lombard peasant life in a '' cascina'' (farmhouse) of the late 19th century. It has some similarities with the earlier Italian neor ...
'' (''L' Albero Degli Zoccoli,'' 1978) refers in its title to alder, typically used to make clogs as in this movie's plot.Ontano nero
(''tr. Black Alder'') accessed 17 November 2020 ''uomoenatura.it''


References


Further reading

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External links


Flora Europaea: ''Alnus''

Flora of Bolivia: ''Alnus''

Flora of China: ''Alnus''

Flora of North America: ''Alnus''

Flora of Pakistan: ''Alnus''
{{Authority control Taxa named by Philip Miller