Changes

8,636 bytes added ,  13:59, 4 April 2007
no edit summary
{{Taxobox
| color = lightgreen
| name = Birches
| image = Betula pendula winter.jpg
| image_width = 240px
| image_caption = [[Silver Birch]]
| regnum = [[Plant]]ae
| divisio = [[Flowering plant|Magnoliophyta]]
| classis = [[Dicotyledon|Magnoliopsida]]
| ordo = [[Fagales]]
| familia = [[Betulaceae]]
| genus = '''''Betula'''''
| genus_authority = [[Carolus Linnaeus|L.]]
| subdivision_ranks = Species
| subdivision =
''Many species;''<br/>
''see text and [[Betula classification|classification]]''
}}

'''Birch''' is the name of any [[tree]] of the genus '''''Betula''''', in the family [[Betulaceae]], closely related to the [[beech]]/[[oak]] family, [[Fagaceae]]. These are generally small to medium-size [[tree]]s or [[shrub]]s, mostly of northern [[temperate]] climates. The simple [[leaf|leaves]] may be toothed or lobed. The fruit is a small [[samara (fruit)|samara]], although the wings may be obscure in some species. They differ from the [[alder]]s (''Alnus'', the other genus in the family) in that the female [[catkin]]s are not woody and disintegrate at maturity, falling apart to release the seeds, unlike the woody cone-like female alder catkins.

The common name ''birch'' is derived from an old [[Germanic language|Germanic]] root similar to ''birka''. The [[Proto-Germanic]] [[rune]] [[berkanan]] is named after the birch. The botanic name ''Betula'' is from the original [[Latin]].

Birch is used as a food plant by the [[larva]]e of a large number of [[Lepidoptera]] species, see [[List of Lepidoptera which feed on Birches]].

The birch is considered a [[National emblem|national tree]] of [[Russia]], where it used to be worshipped as a goddess during the [[Semik|Green Week]] in early June.

===Species===
See also: [[Betula classification]] birch

;Birches of [[North America]] include:
*''Betula alleghaniensis'' - [[Yellow Birch]] (''B. lutea'')
*''Betula cordifolia'' - [[Mountain Paper Birch]]
*''Betula glandulosa'' - [[American Dwarf Birch]]
*''Betula lenta'' - [[Sweet Birch]], Cherry Birch, or Black Birch
**''Betula lenta'' subsp. ''uber'' - [[Virginia Round-Leaf Birch]] (endemic, Cressy Creek, [[Smyth County, Virginia]])
*''Betula michauxii'' - [[Newfoundland Dwarf Birch]]
*''Betula nana'' - [[Dwarf Birch]] or Bog Birch (also in northern Europe and Asia)
*''Betula neoalaskana'' - [[Alaska Birch]] or Yukon Birch
*''Betula nigra'' - [[River Birch]] or Black Birch
*''Betula occidentalis'' - [[Water Birch]] or Red Birch (''B. fontinalis'')
*''Betula papyrifera'' - [[Paper Birch]], Canoe Birch or American White Birch
*''Betula populifolia'' - [[Gray Birch]]
*''Betula pumila'' - [[Swamp Birch]]

;Birches of [[Europe]] and [[Asia]] include:
*''Betula albosinensis'' - [[Chinese Red Birch]]
**''Betula albosinensis'' var. ''septentrionalis'' - [[North Chinese Red Birch]]
*''Betula alnoides'' - [[Alder-leaf Birch]]
*''Betula austrosinensis'' - [[South China Birch]]
*''Betula chinensis'' - [[Chinese Dwarf Birch]]
*''Betula ermanii'' - [[Erman's Birch]]
*''Betula grossa'' - [[Japanese Cherry Birch]]
*''Betula jacquemontii'' (''Betula utilis'' subsp. ''jacquemontii'') - [[White-barked Himalayan Birch]]
*''Betula mandschurica'' - [[Manchurian Birch]]
**''Betula mandschurica'' var. ''japonica'' - [[Japanese Birch]]
*''Betula maximowiczii'' - [[Monarch Birch]]
*''Betula medwediewii'' - [[Caucasian Birch]]
*''Betula nana'' - [[Dwarf Birch]] (also in northern North America)
*''Betula pendula'' - [[Silver Birch]]
*''Betula platyphylla'' (''Betula pendula'' var. ''platyphylla'') - [[Siberian Silver Birch]]
*''Betula pubescens'' - [[Downy Birch]], White Birch or European White Birch (also in northern Asia)
**''Betula pubescens'' subsp. ''tortuosa'' - [[White Birch|Arctic White Birch]] (subarctic Eurasia, Greenland)
*''Betula szechuanica'' (''Betula pendula'' var. ''szechuanica'') - [[Sichuan Birch]]
*''Betula utilis'' - [[Himalayan Birch]]

:''Note: many American texts have ''B. pendula'' and ''B. pubescens'' confused, though they are distinct species with different chromosome numbers''

==Uses==
Birches are versatile trees. T
he [[sap (plant)|sap]], bark, leaves, wood, twigs, and roots are used for food, construction materials, drums, medicinal treatments, [[lubricant]]s, and other practical applications.

Due to birch [[Wood pulp|pulp]]’s short-fibre qualities, this [[hardwood]] can be used to make printing paper.

In northern [[latitude]]s birch is however considered to be the most important [[allergy|allergenic]] tree [[pollen]], with an estimated 15-20% of [[hay fever]] sufferers sensitive to birch pollen grains.

Extracts of birch are used for flavoring or leather oil, and in cosmetics such as [[soap]] or [[shampoo]]. In the past, commercial oil of wintergreen ([[methyl salicylate]]) was made from the [[Sweet Birch]] (''Betula lenta''). ''Birch tar'' or ''Russian Oil'', extracted from birch bark, was used as a lubricant or glue and also for medicinal purposes. [[Xylitol]] can also be extracted from birch, a [[sugar alcohol]] [[artificial sweetener]], which has shown effectiveness in preventing, and in some cases repairing, [[tooth decay]].

In [[Belarus]], [[Russia]], [[the Baltic States]], [[Finland]], and parts of northern [[China]], [[birch sap]] is drunk as a refreshing beverage, and is believed to have [[tonic]] qualities. It is watery and pale green in color, with a slightly sweet flavor, and is bottled commercially. Birch sap may also made into [[kvass]]. The sap of particular birch species may also be rendered into [[birch syrup]], [[vinegar]], [[birch beer|beer]], soft drinks, and other foods. In contrast to [[maple syrup]], birch syrup is very difficult to produce, making it more expensive than other food syrups. It is also considerably less sweet than maple syrup and the sap for syrup production is not available until a month later than maple's. The syrup is made mainly in [[Alaska]] (from Alaska Birch) and [[Russia]] (from several species), and more rarely elsewhere.

[[Silver Birch]] (''Betula pendula'') is [[Finland]]'s national tree. Occasionally one uses leafy, fragrant twigs of silver birch to gently beat oneself in a [[sauna]]. The twigs are called ''vihta'' or ''vasta''. This has a relaxing effect on the muscles.

Birch is used as [[firewood]] due to its high [[calorific value]] per unit weight and unit volume.

Birch leaves are used to make a [[diuretic]] [[tea]] and to make extracts for [[dye]]s and cosmetics.

Birch twigs were bound in a bundle, also called birch, to be used for [[birching]], a form of [[physical punishment|corporal punishment]].

Many of the [[First Nations]] of [[North America]] prized the birch for its bark, which due to its light weight, flexibility, and the ease with which it could be stripped from fallen trees, was often used for the construction of strong, waterproof but lightweight [[canoe]]s, bowls, and [[tipi]]s. The bark is high in [[betulin]] and betulinic acid, [[phytochemical]]s which have potential as [[pharmaceutical]]s, and other chemicals which show promise as industrial lubricants.

Birch bark can be soaked until moist in hot water, and then formed into a cast for a broken arm {{Fact|date=February 2007}}. It is also used in starting fires. The bark will burn very well, even when wet, because of the oils it contains. With care, the bark can be split into very thin sheets that will ignite from even the smallest of sparks.

Birches also have spiritual importance in several religions, both modern and historical.

Birch wood is also used to make drums. They produce boosted high and low frequencies with loud low end punch that is ideal for studio recordings.

According to the [[Food Network]] series [[Unwrapped]], birch is a preferred wood for the manufacture of [[toothpicks]].

The inner bark of birch can be ingested.

==References==
{{Commonscat|Betula}}
*[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=103887 Flora of North America: ''Betula'']
*[http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=103887 Flora of China: ''Betula'']
*[http://www.inmygarden.org/archives/2005/02/great_americans_18.html#more The Monday Garden: Birches]

<gallery>
Image:Birchandma
ple.jpg|Birch tree (foreground), showing characteristic white bark
Image:Birchbark.jpg|Closeup of [[Silver Birch]] bark
Image:BirchBark2.JPG|A gnarled Silver Birch bark
Image:Betula.jpg|A betula nana or tortuosa at [[Kvaløya]]
</gallery>

[[Category:Betulaceae]]

In India the thin bark coming off in winter was used as writing paper. This has excellent life. the paper is known as bhoorj patra. Bhoorj is the sanskrit name of tree and patra means paper