What is 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-s