Birch

Birch
Silver Birch
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Fagales
Family: Betulaceae
Genus: Betula
L.
Species

Many species;
see text and classification

Birch is the name of a certain tree of the genus Betula (pronounced /ˈbɛtjʊlə/ Bé-tu-la),[1] in the family Betulaceae, closely related to the beech/oak family, Fagaceae.

Contents

Description

The front and rear sides of a piece of birch bark.

Birch species are generally small to medium-size trees or shrubs, mostly of temperate climates. The simple leaves may be toothed or pointed. The fruit is a small samara, although the wings may be obscure in some species. They differ from the alders (Alnus, other genus in the family) in that the female catkins are not woody and disintegrate at maturity, falling apart to release the seeds, unlike the woody cone-like female alder catkins.

The bark of all birches is characteristically marked with long horizontal lenticels, and often separates into thin papery plates, especially upon the Paper Birch. It is practically imperishable, due to the resinous oil which it contains. Its decided color gives the common names Red, White, Black, Silver and Yellow to different species.

The buds form early and are full grown by midsummer, all are lateral, no terminal bud is formed; the branch is prolonged by the upper lateral bud. The wood of all the species is close-grained with satiny texture and capable of taking a fine polish; its fuel value is fair.

The leaves of the different species vary but little. All are alternate, doubly serrate, feather-veined, petiolate, and stipulate. They often appear in pairs, but these pairs are really borne on spur-like two-leaved lateral branchlets.[2]

Flower and fruit

The flowers are monoecious, opening with or before the leaves and borne on three-flowered clusters in the axils of the scales of drooping or erect aments. Staminate aments are pendulous, clustered or solitary in the axils of the last leaves of the branch of the year or near the ends of the short lateral branchlets of the year. They form in early autumn and remain rigid during the winter. The scales of the staminate aments when mature are broadly ovate, rounded, yellow or orange color below the middle, dark chestnut brown at apex. Each scale bears two bractlets and three sterile flowers, each flower consisting of a sessile, membranaceous, usually two-lobed, calyx. Each calyx bears four short filaments with one-celled anthers or strictly, two filaments divided into two branches, each bearing a half-anther. Anther cells open longitudinally. The pistillate aments (catkins) are erect or pendulous, solitary; terminal on the two-leaved lateral spur-like branchlets of the year. The pistillate scales are oblong-ovate, three-lobed, pale yellow green often tinged with red, becoming brown at maturity. These scales bear two or three fertile flowers, each flower consisting of a naked ovary. The ovary is compressed, two-celled, and crowned with two slender styles; the ovule is solitary.

The ripened pistillate ament is called a strobile and bears tiny winged nuts, packed in the protecting curve of each brown and woody scale. These nuts are pale chestnut brown, compressed, crowned by the persistent stigmas. The seed fills the cavity of the nut. The cotyledons are flat and fleshy. All the species are easily grown from seed.[2]

Name

The common name birch is derived from an old Germanic root, birka, with the Proto-Indo-European root *bherəg, "white, bright; to shine." The Proto-Germanic rune berkanan is named after the birch. The botanic name Betula is from the original Latin.

Ecology

Birches often form even-aged stands on light, well-drained, particularly acidic soils. They are regarded as pioneer species, rapidly colonising open ground especially in secondary successional sequences following a disturbance or fire. Birches are early tree species to establish in primary successions and can become a threat to heathland if the seedlings and saplings are not suppressed by grazing or periodic burning. Birches are generally lowland species, but some species such as Betula nana have a montane distribution.

Birch foliage is used as a food plant by the larvae of a large number of Lepidoptera (butterflies and moths) species; see List of Lepidoptera that feed on birches.

Species

Birches of North America include
Birches of Europe and Asia include
Birch species are generally small to medium-size trees or shrubs, mostly of temperate climates. The simple leaves may be toothed or pointed. The fruit is a small samara, although the wings may be obscure in some species. They differ from the alders (Alnus, other genus in the family) in that the female catkins are not woody and disintegrate at maturity, falling apart to release the seeds, unlike the woody cone-like female alder catkins.

The bark of all birches is characteristically marked with long horizontal lenticels, and often separates into thin papery plates, especially upon the Paper Birch. It is practically imperishable, due to the resinous oil which it contains. Its decided color gives the common names Red, White, Black, Silver and Yellow to different species. The buds form early and are full grown by midsummer, all are lateral, no terminal bud is formed; the branch is prolonged by the upper lateral bud. The wood of all the species is close-grained with satiny texture and capable of taking a fine polish; its fuel value is fair. The leaves of the different species vary but little. All are alternate, doubly serrate, feather-veined, petiolate, and stipulate.

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

Uses

Birch plywood

Birch wood is fine-grained and pale in colour, often with an attractive satin-like sheen. Ripple figuring may occur, increasing the value of the timber for veneer and furniture-making. The highly-decorative Masur (or Karelian) birch, from Betula verrucosa var. carelica has ripple texture combined with attractive dark streaks and lines. Birch wood is suitable for veneer, and birch ply is among the strongest and most dimensionally-stable plywoods, although it is unsuitable for exterior use.

Birch ply is made from laminations of birch veneer. It is light but strong and has many other good properties. Birch ply is used to make longboards (skateboard), giving it a strong yet flexy ride. It is also used (often in very thin grades with many laminations) for making model aircraft.

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 is thermoplastic and waterproof; it was used as a glue on, for example, arrows, and also for medicinal purposes.[3]

Fragrant twigs of silver birch are used in saunas to relax the muscles.

Birchleaves

Birch is also associated with the feast of Pentecost in Germany, Central & Eastern Europe, and Russia, where its branches are used as decoration for churches and homes on this day.

Birch leaves make a diuretic tea and to make extracts for dyes and cosmetics.

Ground birch bark, fermented in sea water, is used for seasoning the woolen, hemp or linen sails and hemp rope of traditional Norwegian boats.

Birch twigs were bound in a bundle, also called birch, to be used for birching, a form of 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 canoes, bowls, and wigwams.

The Hughes H-4 Hercules was made mostly of birch wood, despite its better-known moniker, "The Spruce Goose".

Birch is used as firewood due to its high calorific value per unit weight and unit volume. It burns well, without popping, even when frozen and freshly hewn. The bark will burn very well even when wet because of the oils it contains. With care, it can be split into very thin sheets that will ignite from even the smallest of sparks.

Birch juice extracted by cutting the standing trees is considered a common drink in rural Ukraine, Belarus, and Russia. The juice is sometimes extracted, bottled and sold commercially. Similarly in the British Isles the sap is often used to make a wine.[4]

Birch seeds are used as leaf litter in miniature terrain models.[5]

Birch flowers is the English marketing name for the catkins of the broussonetia luzonica tree. Known in the Philippines as himbabao or alukon, these flowers are commonly used in the cuisine of northeastern Luzon. However, despite their English name and the similar appearance of their flowers, broussonetia luzonica is not in any way related to the birch tree. [6]

Medical

The chaga mushroom is an adaptogen that grows on white birch trees, extracting the birch constituents and is used to treat cancer.

Birch bark is high in betulin and betulinic acid, phytochemicals which have potential as pharmaceuticals, and other chemicals which show promise as industrial lubricants.

Birch bark can be soaked until moist in water, and then formed into a cast for a broken arm.[7]

The inner bark of birch can be ingested safely.

In northern latitudes birch is considered to be the most important allergenic tree pollen, with an estimated 15-20% of hay fever sufferers sensitive to birch pollen grains.

Paper

A birch bark inscription excavated from Novgorod, circa 1240–1260

Birch pulp’s short-fibres allow this hardwood to be used to make paper. In India, the birch (Sanskrit: भुर्ज, bhurj) holds great historical significance in the culture of Northern India, where the thin bark coming off in winter was extensively used as writing paper. Birch paper (Sanskrit: भुर्ज पत्र, bhurj pətrə) is exceptionally durable and was the parchment used for many ancient Indian texts.[8][9] This bark also has been used widely in ancient Russia as note paper (beresta) and for decorative purposes and even making footwear.

Tonewood

Baltic Birch is among the most sought after wood in the manufacture of speaker cabinets. Birch has a natural resonance that peaks in the high and low frequencies, which are also the hardest for speakers to reproduce. This resonance compensates for the roll-off of low and high frequencies in the speakers, and evens the tone. Birch is known for having "natural EQ."

Drums are often made from Birch. Prior to the 1970s, Birch was one of the most popular drum woods. Because of the need for greater volume and midrange clarity, drums were made almost entirely from maple until recently, when advancements in live sound reinforcement and drum microphones have allowed the use of Birch in high volume situations. Birch drums have a natural boost in the high and low frequencies, which allow the drums to sound fuller.

Birch wood is sometimes used as a tonewood for semi-acoustic and acoustic guitar bodies and occasionally used for solid-body guitar bodies. Birch wood is also a common material used in mallets for keyboard percussion.

Culture

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

They are associated with the Tír na nÓg, the land of the dead and the Sidhe, in Gaelic folklore, and as such frequently appear in Scottish, Irish, and English folksongs and ballads in association with death, or fairies, or returning from the grave.

The birch tree is considered a national tree of Russia,[10] where it used to be worshipped as a goddess during the Green Week in early June.

It is also New Hampshire's state tree.

In the Swedish city of Umeå the silver birch tree has a special place after it was ravaged by fires that spread all over the city and nearly burnt it down to the ground, if it hadn't been for some birches that, supposedly, halted the spread of the fire. After that it was decided to plant more silver birch trees all over the city, they then adopted an unofficial name of "City of the Birches (Björkarnas stad)". Also, the Hockey team of Umeå is called Björklöven, or "The birchleaves".

In parts of Germany, young men erect decorated birch trees in front of the houses of their love interests on the night of May 1st to show their feelings.

Gallery

Birch bark can easily be peeled off

Birch Bark up close

A lone birch at sunset in the New Forest

See also

References

  1. ↑ Sunset Western Garden Book, 1995:606–607
  2. ↑ 2.0 2.1 Keeler, Harriet L. (1900). Our Native Trees and How to Identify Them. New York: Charles Scriber's Sons. pp. 295–297. 
  3. ↑ Birch Tar - How to collect it Archived February 27, 2008 at the Wayback Machine.
  4. ↑ "The Woodland Trust"
  5. ↑ Daniel Joyce, "Birch Seed Leaves", ReaperMiniatures.com
  6. ↑ Andrew Grygus, "Alokon", [1]
  7. ↑ William Arthur Clark (1937-01-01). "History of Fracture Treatment Up to the Sixteenth Century" (– Scholar search). The Journal of Bone & Joint Surgery (Needham, MA, USA: The Journal of Bone & Joint Surgery, Inc.) 19 (1): 61–62. http://www.ejbjs.org/cgi/reprint/19/1/47.pd. "Another method cited was that of splints made of birch bark soaked in water until quite soft. They were then carefully fitted to the limb and tied with bark thongs. On drying, they became stiff and firm. There is no record of the use of extension, but, nevertheless, very few crippled and deformed Indians were to be seen.". 
  8. ↑ Sanjukta Gupta, "Lakṣmī Tantra: A Pāñcarātra Text", Brill Archive, 1972, ISBN 90-04-03419-6. Snippet:... the text recommends that the bark of the Himalayan birch tree (bhurja-patra) should be used for scribbling mantras ...
  9. ↑ Amalananda Ghosh, "An Encyclopaedia of Indian Archaeology", BRILL, 1990, ISBN 90-04-09264-1. Snippet:... Bhurja-patra, the inner bark on the birch tree grown in the Himalayan region, was a very common writing material ...
  10. ↑ "Symbols of Russia" Education document of Tambov State Department of Culture «Guidance Center of National Creation and Leisure» (Russian)

John Grimshaw, New Trees, Recent introductions to cultivation, Kew Publishing, RBG Kew, 2009 pp163–174

External links