View source for Alder

{{Taxobox
| name = Alder
| image = Tagalder8139.jpg
| image_width = 250px
| image_caption = ''Alnus serrulata'' (Tag Alder)<br />Male catkins on right,<br />mature female catkins left<br />[[Johnsonville, South Carolina]]
| regnum = [[Plant]]ae
| divisio = [[flowering plant|Magnoliophyta]]
| classis = [[dicotyledon|Magnoliopsida]]
| ordo = [[Fagales]]
| familia = [[Betulaceae]]
| genus = '''''Alnus'''''
| genus_authority = [[Philip Miller|Mill.]]
| subdivision_ranks = Species
| subdivision = 
About 20-30 species, see text.
}}
[[File:Common alder in Holma.jpg|thumb|Common alder in Holma, Sweden ]]
'''Alder''' is the common name for about 30 [[species|kinds]] of [[tree]]s and [[shrub]]s of the '''''Alnus''''' [[genus]]. They are a part of the [[birch]] [[family (biology)|family]] (''Betulaceae''). Most of them are smaller in size. Leaves are mostly [[deciduous]], only very few alders are [[evergreen]].

Alder trees are found in all parts of the northern hemisphere and they are often found on poor and/or wet soil. Alders have [[:en:Alternate_leaf#Arrangement_on_the_stem|alternate]] simple leaves with a toothed edge. The male flowers are in the form of hanging catkins and the female flowers are much smaller catkin-like structures ''(see image).'' The [[pollen]] is transferred from the male to the female flower by the wind. The female flower parts develop into little, green, rounded cone-like fruits which turn brown in autumn and open to release the seeds. 

The best known species are the [[:en:Alnus glutinosa|Black Alder]], which can be seen throughout [[Europe]]. The largest is probably the [[:en:Alnus rubrus|Red Alder]], [[native]] to [[North America]]. It reaches about 32–35 metres in height. The widespread [[:en:Green Alder|Green Alder]] is a shrub, rarely more than 5m high. The commonest alder in the [[UK]] is the Black Alder, also called the Common Alder or European Alder.  

Alder is a preferred tree for [[bee]]s, especially in spring. It is also used to make [[charcoal]]. 

{{wikispecies|Alnus}}


{{biology-stub}}

[[Category:Trees]]
[[Category:Betulaceae]]