Overview

Brief Summary

Birches (genus Betula) are one of the world’s most widely distributed woody plant, living across every continent in the northern hemisphere particularly in northern temperate and boreal climates near water.  The family Betulaceae, to which they belong, also contains the alders, hazels and hornbeams.  Birches are broadleaved deciduous hardwoods, typically short-lived species that often grow as small- to medium-sized tree and shrub pioneers into disturbed areas.

In response to evolutionary and recent climate change patterns, birch species have diversified morphologically, genetically, ecologically and physiologically.  Like many wind-pollinated species, much hybridization and polyploidy has occurred among birches, leading to poor consensus about individual species.  The genus is variously described as containing between 30-60 known species, broken into five groups (although other schemes have also been proposed):
   wintergreen birches (Betulenta)
   broadleaf birches (Betulaster)
   costate birches (Neurobetula)
   typical birches (Betula)
   dwarf birches (Chamaebetula)
Recent nuclear molecular phylogenetic study, however, suggests that Neurobetula and Chamaebetula may not form true (monophyletic) groups (Wikipedia 2014; Li et al. 2007)

Birches are recognizable by characteristic, conspicuous horizontal markings (lenticels) on their bark.  The bark often separates into thin, papery plates, and many species produce resinous oil making it resistant to decay.  Human cultures as early as the 1st Century CE and continuing to the current day have used bark from various birch species as paper for writing (Wikipedia 2 September 2014).  Medical properties and the nutritional value of birch bark have also been appreciated since prehistory, and for some time the cosmetic industry has exploited and explored chemicals in birch bark.  In the last decade, phytochemicals isolated from the bark of many species show great promise for multiple uses, including new drug development.  One example is recently recognized activities of birch bark triterpenoids, which represent a new class of anti-cancer and anti-HIV substances with a novel mechanism of action (Ebeling et al. 2014; Krasutsky 2007). 

Birch wood is fine grained, attractive, hard, flexible and strong and used for many building purposes as well as for quality, highly flamable firewood.  Birch sap is harvested for syrup and fermented drinks, e.g. birch beer (Wikipedia 26 September 26, 2014). 

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records:378
Specimens with Sequences:543
Specimens with Barcodes:387
Species:49
Species With Barcodes:49
Public Records:162
Public Species:31
Public BINs:0
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Conservation

Conservation Status

Betula species listed on IUCN red lists:

IUCN Red List of extinct in the wild species (30 August 2014 as listed Wikipedia 31 August 2014):
Betula szaferi

IUCN Critically endangered list (30 August 2014 Version 2014.2, as listed Wikipedia 31 August 2014):
Betula halophila
Betula jarmolenkoana
Betula kirghisorum
Betula schugnanica
Betula uber

IUCN Red List of Endangered Species (29 January 2010 as listed Wikipedia 23 June 2014):
Betula pendula ssp. fontqueri
Betula pendula var. parvibracteata
Betula talassica
Betula tianschanica

IUCN Red List of Near Threatened Species  (12 March 2010 as listed Wikipedia 18 September 2013):
Alnus maritima
Betula raddeana
Betula recurvata

IUCN Red List of Vulnerable species (30 January 2010 as listed Wikipedia 30 January 2014):
Betula oycoviensis
Betula pamirica

IUCN 2.3 identified as conservation dependent (Wikipedia 12 October 2011)
Betula browicziana

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Wikipedia

Birch

For other uses, see Birch (disambiguation).

Birch is a broadleaved deciduous hardwood tree of the genus Betula (/ˈbɛtjʊlə/),[2] in the family Betulaceae, which also includes alders, hazels, and hornbeams, and is closely related to the beech/oak family, Fagaceae. The genus Betula contains 30 to 60 known taxa of which 11 are on the IUCN 2011 Red List of Threatened Species. They are typically rather short-lived pioneer species widespread in the Northern Hemisphere, particularly in northern temperate and boreal climates. This tree is sometimes called "The Watchful Tree" because of eye-like impressions on the bark.[3]

Etymology[edit]

The common name birch comes from Old English birce, bierce, from Proto-Germanic *berk-jōn (cf. German Birke, West Frisian bjirk), an adjectival formation from *berkōn (cf. Dutch berk, Low German Bark, Norwegian bjørk), itself from the Proto-Indo-European root *bʰerHǵ- ~ bʰrHǵ-, which also gave Lithuanian béržas, Ukrainian beréza, Albanian bredh ‘fir’, Ossetian bærz(æ), Sanskrit bhurja, Polish brzoza, Latin fraxinus ‘ash (tree)’. This root is presumably derived from *bʰreh₁ǵ- ‘to shine’, in reference to the birch's white bark. The Proto-Germanic rune berkanan is named after the birch.

The generic name betula is from Latin, which is a diminutive borrowed from Gaulish betua (cf. Old Irish bethe, Welsh bedw).

Description[edit]

The front and rear sides of a piece of birch bark

Birch species are generally small to medium-sized trees or shrubs, mostly of temperate climates. The simple leaves are alternate, singly or 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.[4] 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 resistant to decay, due to the resinous oil it contains. Its decided color gives the common names gray, white, black, silver and yellow birch 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.

Flower and fruit[edit]

The flowers are monoecious, opening with or before the leaves and borne once fully grown these leaves are usually 3–6 millimetres (0.12–0.24 in) long on three-flowered clusters in the axils of the scales of drooping or erect catkins or 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 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.

Ecology[edit]

Birch trees near stream in Hankasalmi, Finland
A stand of birch trees
Cherry trees in autumn

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. In the British Isles, there is some difference between the environments of Betula pendula and Betula pubescens, and some hybridization, though both are "opportunists in steady-state woodland systems". Mycorrhizal fungi, including sheathing (ecto)myccorhizas, are found in some cases to be beneficial to tree growth.[5]

Birch foliage is used as a food plant by the larvae of a large number of lepidopteran (butterflies and moths) species.

Species[edit]

Birch leaves
Birches native to Europe and Asia include
  1. Betula albosinensis—Chinese red birch (northern + central China)
  2. Betula alnoides—alder-leaf birch (China, Himalayas, northern Indochina)
  3. Betula ashburneri (Bhutan, Tibet, Sichuan, Yunnan Provinces in China)
  4. Betula baschkirica (eastern European Russia)
  5. Betula bomiensis (Tibet)
  6. Betula calcicola (Sichuan + Yunnan Provinces in China)
  7. Betula celtiberica (Spain)
  8. Betula chichibuensis (Chichibu region of Japan)
  9. Betula chinensis—Chinese dwarf birch (China, Korea)
  10. Betula coriaceifolia (Uzbekistan)
  11. Betula corylifolia (Honshu Island in Japan)
  12. Betula costata (northeastern China, Korea, Primorye region of Russia)
  13. Betula cylindrostachya (Himalayas, southern China, Myanmar)
  14. Betula dahurica (eastern Siberia, Russian Far East, northeastern China, Mongolia, Korea, Japan)
  15. Betula delavayi - (Tibet, southern China)
  16. Betula ermanii—Erman's birch (eastern Siberia, Russian Far East, northeastern China, Korea, Japan)
  17. Betula falcata (Tajikistan)
  18. Betula fargesii (Chongqing + Hubei Provinces in China)
  19. Betula fruticosa (eastern Siberia, Russian Far East, northeastern China, Mongolia, Korea, Japan)
  20. Betula globispica (Honshu Island in Japan)
  21. Betula gmelinii (Siberia, Mongolia, northeastern China, Korea, Hokkaido Island in Japan)
  22. Betula grossa—Japanese cherry birch (Japan)
  23. Betula gynoterminalis (Yunnan Province in China)
  24. Betula honanensis - (Henan Province in China)
  25. Betula humilis or Betula kamtschatica— Kamchatka birch platyphylla (northern + central Europe, Siberia, Kazakhstan, Xinjiana, Mongolia, Korea)
  26. Betula insignis - (southern China)
  27. Betula karagandensis (Kazakhstan)
  28. Betula klokovii (Ukraine)
  29. Betula kotulae (Ukraine)
  30. Betula litvinovii (Turkey, Iran, Caucasus)
  31. Betula luminifera (China)
  32. Betula maximowiczii—monarch birch (Japan, Kuril Islands)
  33. Betula medwediewii—Caucasian birch (Turkey, Iran, Caucasus)
  34. Betula megrelica (Republic of Georgia)
  35. Betula microphylla (Siberia, Mongolia, Xinjiang, Kazakhstan, Kyrgyzstan, Uzbekistan)
  36. Betula nana—dwarf birch (northern + central Europe, Russia, Siberia, Greenland, Northwest Territories of Canada))
  37. Betula pendula—silver birch (widespread in Europe and northern Asia; Morocco; naturalized in New Zealand and scattered locations in US + Canada)
  38. Betula platyphylla (Betula pendula var. platyphylla)—Siberian silver birch (Siberia, Russian Far East, Manchuria, Korea, Japan, Alaska, western Canada)
  39. Betula potamophila (Tajikistan)
  40. Betula potaninii (southern China)
  41. Betula psammophila (Kazakhstan)
  42. Betula pubescens—downy birch, also known as white, European white or hairy birch (Europe, Siberia, Greenland, Newfoundland; naturalized in scattered locations in US)
  43. Betula raddeana (Caucasus)
  44. Betula saksarensis (Khakassiya region of Siberia)
  45. Betula saviczii (Kazakhstan)
  46. Betula schmidtii (northeastern China, Korea, Japan, Primorye region of Russia)
  47. Betula sunanensis (Gansu Province of China)
  48. Betula szechuanica (Betula pendula var. szechuanica)—Sichuan birch (Tibet, southern China)
  49. Betula tianshanica (Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan, Xinjiang, Mongolia)
  50. Betula utilis—Himalayan birch (Afghanistan, Central Asia, China, China, Tibet, Himalayas)
  51. Betula wuyiensis (Fujian Province of China)
  52. Betula zinserlingii (Kyrgyzstan)

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

Birches native to North America include
  1. Betula alleghaniensis—yellow birch (B. lutea) (eastern Canada, Great Lakes, Northeastern US, Appalachians)
  2. Betula cordifolia—mountain paper birch (eastern Canada, Great Lakes, Northeastern US)
  3. Betula glandulosa—American dwarf birch (Siberia, Mongolia, Russian Far East, Alaska, Canada, Greenland, mountains of western US and New England, Aridondacks)
  4. Betula lenta—sweet birch, cherry birch, or black birch (Quebec, Ontario, eastern US)
  5. Betula michauxii—Newfoundland dwarf birch (Newfoundland, Labrador, Quebec, Nova Scotia)
  6. Betula minor—dwarf white birch (eastern Canada, mountains of northern New England and Adirondacks)
  7. Betula nana—dwarf birch or bog birch (also in northern Europe and Asia)
  8. Betula nigra—river birch or black birch (eastern US)
  9. Betula occidentalis—water birch or red birch (B. fontinalis) (Alaska, Yukon, Northwest Territories, western Canada, western US)
  10. Betula papyrifera—paper birch, canoe birch or American white birch (Alaska, most of Canada, northern US)
  11. Betula populifolia—gray birch (eastern Canada, northeastern US)
  12. Betula pumila—swamp birch (Alaska, Canada, northern US)


Uses[edit]

Birch plywood
Unfinished birch
Finished birch

Due to the hardness of Birch, it is better to shape it with power tools, as it is quite difficult to work it with hand tools.[6]

  • 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 textures combined with attractive dark streaks and lines. Birch wood is suitable for veneer, and birch plywood is among the strongest and most dimensionally stable plywoods, although it is unsuitable for exterior use.
  • Birch plywood is made from laminations of birch veneer. It is light but strong, and has many other good properties. Birch plywood is used to make longboards (skateboard), giving it a strong yet flexible 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.[7]
  • Fragrant twigs of silver birch are used in saunas to relax the muscles.
  • Birch is also associated with the feast of Pentecost in Germany, Central and Eastern Europe, and Russia, where its branches are used as decoration for churches and homes on this day.
  • Birch leaves are used to make a diuretic tea and 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 bound in a bundle, also called birch, were used for birching, a form of corporal punishment.
  • Many of the indians 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 plywood was specified by the BBC as the only wood that can be used in making the cabinets of the long-lived LS3/5A loudspeaker.[8]
  • 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 sap is a traditional drink in Northern Europe, Russia, and Northern China. The sap is also bottled and sold commercially. Birch sap can be used to make birch syrup, which is used like maple syrup for pancakes and waffles. Birch wood can be used to smoke foods.
  • Birch seeds are used as leaf litter in miniature terrain models.[9]
  • "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, B. luzonica is not in any way related to the birch tree.[10]
  • Birch oil is used in the manufacture of Russia leather, a water-resistant leather.

Medical[edit]

  • Birch bark is high in betulin and betulinic acid, phytochemicals which have potential as pharmaceuticals, and other chemicals which show promise as industrial lubricants.[citation needed]
  • Birch buds are used in folk medicine.[11]
  • Birch bark can be soaked until moist in water, and then formed into a cast for a broken arm.[12]
  • 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. The major allergen is a protein called Bet v I.

Paper[edit]

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

Wood pulp made from birch gives relatively long and slender fibres for a hardwood. The thin walls cause the fibre to collapse upon drying, giving a paper with low bulk and low opacity. The birch fibres are, however, easily fibrillated and give about 75% of the tensile strength of softwood[clarification needed].[13] The low opacity makes it suitable for making glassine.

In India, the birch (Sanskrit: भुर्ज, bhurja) holds great historical significance in the culture of North India, where the thin bark coming off in winter was extensively used as writing paper. Birch paper (Sanskrit: भुर्ज पत्र, bhurja patra) is exceptionally durable and was the material used for many ancient Indian texts.[14][15] The Roman period Vindolanda tablets also use birch as a material on which to write and birch bark was used widely in ancient Russia as note paper (beresta) and for decorative purposes and even making footwear.

Tonewood[edit]

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". http://www.soundonsound.com/sos/1996_articles/feb96/eq.html

Drums are often made from birch. Prior to the 1970s, it 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[clarification needed], when advances 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 allows the drums to sound fuller.

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

Culture[edit]

  • Birches have spiritual importance in several religions, both modern and historical.
  • In Celtic cultures, the birch symbolises growth, renewal, stability, initiation and adaptability. The birch is highly adaptive and able to sustain harsh conditions with casual indifference. Proof of this adaptability is seen in its easy and eager ability to repopulate areas damaged by forest fires or clearings.
  • The Czech word for the month of March, Březen, is derived from the Czech word bříza meaning birch, as birch trees flower in March under local conditions.
  • They are also 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.
  • It is also New Hampshire's state tree.
  • Robert Frost, an American poet, pays homage to the act of climbing birch trees in one of his more famous poems, "Birches."
  • In the Swedish city of Umeå, the silver birch tree has a special place. In 1888, the Umeå city fire spread all over the city and nearly burnt it down to the ground, but some birches, supposedly, halted the spread of the fire. To protect the city against future fires, it was decided to plant silver birch trees all over the city. Umeå later adopted the unofficial name of "City of the Birches (Björkarnas stad)". Also, the ice hockey team of Umeå is called Björklöven, translated to English "The Birch Leaves".
  • National Tree of Finland and Russia.
  • The leaves of the silver birch tree are used in the festival of St George, held in Novosej and other villages in Albania.[16]

See also[edit]

References[edit]

  1. ^ http://apps.kew.org/wcsp/synonomy.do?name_id=21065
  2. ^ Sunset Western Garden Book, 1995:606–607
  3. ^ Ashburner, K. & McAllister, H.A. (2013). The genus Betula: a taxonomic revision of birches: 1-431. Royal Botanic Gardens, Kew.
  4. ^ Keeler, Harriet L. (1900). Our Native Trees and How to Identify Them. New York: Charles Scriber's Sons. pp. 295–297. 
  5. ^ Birches. (A Symposium, Royal Botanic Garden, Edinburgh 24–26 September 1982. Proceedings of the Royal Society of Edinburgh, 85B, 1–11, 1984.
  6. ^ "Birch". Wood Magazine. Retrieved December 1, 2013. 
  7. ^ "Birch Tar – How to collect it". Archived from the original on February 27, 2008. 
  8. ^ Prakel, David (August 1979). "BBC's Home Service", Hi-Fi Answers, pp67–9 (Courtesy link)
  9. ^ Joyce, Daniel. "Birch Seed Leaves". reapermini.com. 
  10. ^ Grygus, Andrew. "Alokon". Clove Garden. 
  11. ^ White Birch – American Cancer Society (cancer.org)
  12. ^ William Arthur Clark (January 1, 1937). "History of Fracture Treatment Up to the Sixteenth Century". The Journal of Bone & Joint Surgery (Needham, MA, USA: The Journal of Bone & Joint Surgery, Inc.) 19 (1): 61–62. 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. 
  13. ^ Nanko, Hiroki; Button, Alan; Hillman, Dave (2005). The World of Market Pulp. USA: WOMP, LLC. pp. 192–195. ISBN 0-615-13013-5. 
  14. ^ 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 ...
  15. ^ 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 ...
  16. ^ "Traditional celebrations in Novosej". RASP. Retrieved August 28, 2013. 
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