- Alnus viridis
Taxobox
name = Green Alder
image_width = 240px
image_caption = Green Alder "Alnus viridis" (foreground foliage)
regnum =Plant ae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo =Fagales
familia =Betulaceae
genus = "Alnus"
subgenus = "Alnobetula"
species = "A. viridis"
binomial = "Alnus viridis"
binomial_authority = (Chaix.) D.C."Alnus viridis" (Green Alder) is an
alder with a wide range across the cooler parts of theNorthern Hemisphere .Description
It is a large
shrub or smalltree 3-12 m tall with smooth grey bark even in old age. The leaves are shiny green, ovoid, 3-8 cm long and 2-6 cm broad. Theflower s arecatkin s, appearing late in spring after the leaves emerge (unlike other alders which flower before leafing out); the male catkins are pendulous, 4-8 cm long, the female catkins 1 cm long and 0.7 cm broad when mature in late autumn, in clusters of 3-10 on a branched stem. Theseed s are small, 1-2 mm long, light brown with a narrow encircling wing.Distribution
There are four to six
subspecies , some treated as separate species by some authors:
*"Alnus viridis" subsp. "viridis". CentralEurope .
*"Alnus viridis" subsp. "suaveolens".Corsica (endemic).
*"Alnus viridis" subsp. "fruticosa". Northeast Europe, northernAsia , northwesternNorth America .
*"Alnus viridis" subsp. "maximowiczii" ("A. maximowiczii").Japan .
*"Alnus viridis" subsp. "crispa" ("A. crispa", Mountain Alder). Northeastern North America,Greenland .
*"Alnus viridis" subsp. "sinuata" ("A. sinuata", Sitka Alder or Slide Alder). Western North America, far northeastern Siberia.Ecology
"A. viridis" has a shallow root system, and is marked not only by vigorous production of stump suckers, but also by root suckers.
"A. viridis" is a light-demanding, fast-growing shrub that grows well on poorer soils. In many areas, it is a highly characteristic colonist of
avalanche chutes inmountain s, where potentially competing larger trees are killed by regular avalanche damage. "A. viridis" survives the avalanches through its ability to re-grow from the roots and broken stumps. Unlike some other alders, it does not require moist soil, and is a colonist ofscree s and shallow stony slopes. It also commonly grows on subarctic river gravels, particularly in northernSiberia ,Alaska andCanada , occupying areas similarly disrupted by ice floes during spring river ice breakup; in this habitat it commonly occurs mixed with shrubbywillow s.Uses
It is sometimes used for afforestation on infertile soils which it enriches by means of its nitrogen-fixing nodules, while not growing large enough to compete with the intended timber crop. "A. sinuata" can add 55 lbs of nitrogen per acre per year to the soil. [Ewing, Susan. The Great Alaska Nature Factbook. Portland: Alaska Northwest Books, 1996.]
Notes
References
* [http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Alnus&SPECIES_XREF=viridis&TAXON_NAME_XREF=&RANK= Flora Europaea: "Alnus viridis"]
* [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500041 Flora of North America: "Alnus viridis"]
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