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"Silver Birch" redirects here. For the racehorse, seeSilver Birch (horse).

Silver birch
Betula pendula
Silver birch forest,Inari,Finland
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fagales
Family: Betulaceae
Genus: Betula
Subgenus: Betulasubg.Betula
Species:
B. pendula
Binomial name
Betula pendula
Subspecies

See text

Distribution map
Synonyms

See text

Betula pendula,commonly known assilver birch,warty birch,European white birch,[2]orEast Asian white birch,[3]is aspeciesof tree in thefamilyBetulaceae,nativeto Europe and parts of Asia, though in southern Europe, it is only found at higher altitudes. Its range extends into Siberia, China, and southwest Asia in the mountains of northern Turkey, the Caucasus, and northern Iran. It has been introduced into North America, where it is known as theEuropean white birchorweeping birch[4]and is consideredinvasivein some states in the United States and parts of Canada. The tree can also be found in more temperate regions of Australia.[citation needed]

The silver birch is a medium-sizeddeciduoustree that owes its common name to the white peeling bark on the trunk. The twigs are slender and often pendulous and the leaves are roughly triangular withdoubly serratemargins and turn yellow and brown in autumn before they fall. The flowers arecatkinsand the light, winged seeds get widely scattered by the wind. The silver birch is a hardy tree, apioneer species,and one of the first trees to appear on bare or fire-swept land. Many species of birds and animals are found in birch woodland, the tree supports a wide range of insects and the light shade it casts allows shrubby and other plants to grow beneath itscanopy.It is planted decoratively in parks and gardens and is used for forest products such as joinery timber, firewood, tanning, racecourse jumps, and brooms. Various parts of the tree are used intraditional medicineand the bark containstriterpenes,which have been shown to have medicinal properties.

Description

[edit]
Silver birch
Silver birch has often pendulous twigs, after which the tree has received its scientific name.

The silver birch typically reaches 15 to 25 m (49 to 82 ft) tall (exceptionally up to 31 m (102 ft)),[5]with a slender trunk usually under 40 cm (16 in) diameter. The bark on the trunk and branches is golden-brown at first, but later this turns to white as a result of papery tissue developing on the surface and peeling off in flakes, in a similar manner to the closely relatedpaper birch(B. papyrifera). The bark remains smooth until the tree gets quite large, but in older trees, the bark thickens, becoming irregular, dark, and rugged. Young branches have whitishresinwarts and the twigs are slender, hairless, and oftenpendulous.The buds are small and sticky, and development issympodial– the terminal bud dies away and growth continues from a lateral bud. The species ismonoeciouswith male and female catkins found on the same tree.[6]Someshootsare long and bear the malecatkinsat the tip, while others are short and bear female catkins. The immature male catkins are present during the winter, but the female catkins develop in the spring, soon after the leaves unfurl.[5]

Theleaveshave short, slender stalks and are 3 to 7 cm (1.2 to 2.8 in) long, triangular with broad, untoothed, wedge-shaped bases, slender pointed tips, and coarsely double-toothed, serrated margins. They are sticky with resin at first, but this dries as they age, leaving small, white scales. The foliage is a pale to medium green and turns yellow early in the autumn before the leaves fall. In midsummer, the female catkins mature and the male catkins expand and release pollen, and wind pollination takes place. A catkin of Silver birch could produce an average of 1.66 million pollen grains.[7]The small, 1- to 2-mm wingedseedsripen in late summer on pendulous, cylindrical catkins 2 to 4 cm (0.8 to 1.6 in) long and 7 mm (0.3 in) broad. The seeds are very numerous and are separated by scales, and when ripe, the whole catkin disintegrates and the seeds are spread widely by the wind.[5][8]

Silver birch can easily be confused with the similardowny birch(Betula pubescens). Yet, downy birches are characterised by hairy leaves and young shoots, whereas the same parts on silver birch are hairless. The leaf base of silver birch is usually a right angle to the stalk, while for downy birches, it is rounded. In terms ofgenetic structure,the trees are quite different, but do, however, occasionallyhybridize.[6]

Betula pendulasilver birch catkins and leaves, Childwall Woods & Fields,Merseyside

Distribution and habitat

[edit]

The silver birch grows naturally from western Europe eastwards toKazakhstan,theSakha RepublicinSiberia,Mongolia, and theXin gian gprovince in China, and southwards to the mountains of the Caucasus and northern Iran, Iraq, and Turkey. It is also native to northern Morocco and has become naturalised in some other parts of the world.[9]In the southern parts of its range, it is mainly found in mountainous regions. Its light seeds are easily blown by the wind and it is a pioneer species, one of the first trees to sprout on bare land or after a forest fire. It needs plenty of light and does best on dry, acid soils and is found on heathland, mountainsides, and clinging to crags.[5]Its tolerance to pollution make it suitable for planting in industrial areas and exposed sites.[10]It has been introduced into North America, where it is known as the European white birch, and is consideredinvasivein the states ofKentucky,Maryland,Washington,andWisconsin.[11]It isnaturalisedand locally invasive in parts ofCanada.[12]

Taxonomy

[edit]
See also:List of Betula species
Tree in autumn
Tree in winter

Threesubspeciesof silver birch are accepted:[13][1]

  • Betula pendulasubsp.pendula– Europe and eastwards to central Asia
  • Betula pendulasubsp.mandshurica(Regel) Ashburner & McAll.– eastern Asia and western North America; treated by some botanists asBetula platyphylla[14]
  • Betula pendulasubsp.szechuanica(C.K.Schneid.) Ashburner & McAll.– western China, fromQinghaiandGansutoYunnanand southeastXizang,treated by some botanists asBetula szechuanica[14]

B. pendulais distinguished from the relatedB. pubescens,the other common European birch, in having hairless, warty shoots (hairy and without warts in downy birch), more triangular leaves with double serration on the margins (more ovoid and with single serrations in downy birch), and whiter bark often with scattered black fissures (greyer, less fissured, in downy birch). It is also distinguishedcytologically,silver birch beingdiploid(with two sets of chromosomes), whereas downy birch istetraploid(four sets of chromosomes). Hybrids between the two are known, but are very rare, and being triploid, are sterile.[15]The two have differences inhabitatrequirements, with silver birch found mainly on dry,sandysoils, and downy birch more common on wet, poorly drained sites such asclaysoils andpeat bogs.Silver birch also demands slightly more summer warmth than does downy birch, which is significant in the cooler parts of Europe. Many North American texts treat the two species as conspecific (and cause confusion by combining the downy birch's alternative vernacular name 'white birch', with the scientific nameB. pendulaof the other species), but they are regarded as distinct species throughout Europe.[8]

SeveralvarietiesofB. pendulaare no longer accepted, includingB. pendulavar.carelica,fontqueri,laciniata,lapponica,meridionalis,microlepis,andparvibracteata,as well asformsBetula pendulaf.bircalensis,crispa,andpalmeri.[13]Other synonyms include:[13][16]

  • The rejected nameBetula albaL.also applied in part toB. pendula,though also toB. pubescens[17]
  • Betula brachylepisV.N.Vassil.
  • Betula cajanderi f. fruticansKozhevn.
  • Betula carpatica var. sudeticaRchb.
  • Betula coriaceaPamp.
  • Betula cycoviensisSteud.
  • Betula ellipticifoliaV.N.Vassil.
  • Betula etnensisRaf.,sometimes spelledB. aetnensis[18]
  • Betula ferganensisV.N.Vassil.
  • Betula fontqueriRothm.
  • Betula gummiferaBertol.
  • Betula hybridaBlom
  • Betula insularisV.N.Vassil.
  • Betula kossogolicaV.N.Vassil.
  • Betula laciniata(Wahlenb.) Rchb.
  • Betula lobulataKit.
  • Betula ludmilaeV.N.Vassil.
  • Betula microlepisI.V.Vassil.
  • Betula mongolicaV.N.Vassil.
  • Betula montanaV.N.Vassil.
  • Betula oycowiensisBesser,sometimes spelledB. oycoviensis[1]
  • Betula palmataBorkh.
  • Betula parvibracteataPeinado, G.Moreno & A.Velasco
  • Betula platyphylloidesV.N.Vassil.
  • Betula pseudopendulaV.N.Vassil.
  • Betula szaferiJent.-Szaf. ex Staszk.
  • Betula talassicaPoljakov
  • Betula tiulinaeV.N.Vassil.
  • Betula transbaicalensisV.N.Vassil.
  • Betula tristisDippel
  • Betula verrucosaEhrh.
  • Betula virgultosaFr. ex Regel
  • Betula vladimiriiV.N.Vassil.

Ecology

[edit]

The silver birch has an open canopy which allows plenty of light to reach the ground. This allows a variety of mosses, grasses, and flowering plants to grow beneath, which in turn attract insects. Flowering plants often found in birch woods includeprimrose(Primula vulgaris),violet(Viola riviniana),bluebell(Hyacinthoides non-scripta),wood anemone(Anemone nemorosa), andwood sorrel(Oxalis acetosella). Small shrubs that grow on the forest floor includeblaeberry(Vaccinium myrtillus) andcowberry(Vaccinium vitis-idaea).[8] Birds found in birch woodland include thechaffinch,tree pipit,willow warbler,nightingale,robin,woodcock,redpoll,andgreen woodpecker.[10]

The branches of the silver birch often have tangled masses of twigs known aswitch's broomsgrowing among them, caused by the fungusTaphrinabetulina.Old trees are often killed by the decay fungusFomitopsis betulinaand fallen branches rot rapidly on the forest floor. This tree commonly grows with themycorrhizalfungusAmanita muscariain amutualisticrelationship. This applies particularly to acidic or nutrient-poor soils. Other mycorrhizal associates includeLeccinum scabrumandCantharellus cibarius.[8]In addition to mycorrhiza, the presence of microfauna in the soil assists the growth of the tree, as it enhances the mobilization of nutrients.[19]

Birchsawfly(Craesus septentrionalis) larvae feeding on silver birch, West Wales, July 2014

The larvae of a large number of species of butterflies, moths, and other insects feed on the leaves and other parts of the silver birch.[20]In Germany, almost 500 species of insects have been found on silver and downy birch including 106 beetles and 105lepidopterans,with 133 insect species feeding almost exclusively on birch.[21]Birch diebackdisease can affect planted trees, while naturally regenerated trees seem less susceptible.[22]This disease also affectsB. pubescensand in 2000 was reported at many of the sites planted with birch in Scotland during the 1990s.[23]In the United States, the wood is attacked by the bronze birch borer (Agrilus anxius), an insect pest to which it has no natural resistance.[11]

Conservation

[edit]

Betula pendulais considered a species of least concern by theIUCN Red List.[1]The synonymBetula oycowiensis(asB. oycoviensis) was previously listed on the Red List as vulnerable,[24]though it is now considered a synonym ofB. pendulasubsp.pendula.[1][13]B. szaferiwas previously considered extinct in the wild on the Red List, but is now considered a form ofB. pendulawith the presence of a mutant gene, causing it to grow weakly and fruit heavily.[1]

Uses

[edit]
See also:Birch bark
Foliage coloring in autumn
A pair of Finnish traditional shoes woven from strips of birch bark

The silver birch is Finland'snational tree.[25]Leafy, fragrant bunches of young silver birch boughs (calledvihtaorvasta) are used to gently beat oneself while bathing in the Finnishsauna.[26]Silver birch is often planted in parks and gardens, grown for its white bark and gracefully drooping shoots, sometimes even in warmer-than-optimum places such asLos AngelesandSydney.In Scandinavia and other regions of northern Europe, it is grown for forest products such as lumber and pulp, as well as for aesthetic purposes andecosystem services.It is sometimes used as apioneerand nurse tree elsewhere.[5]

Silver birch wood is pale in colour with a light reddish-brown heartwood and is used in making furniture, plywood, veneers, parquet blocks, skis, and kitchen utensils, and inturnery.It makes a good firewood, but is quickly consumed by the flames. Slabs of bark are used for makingroof shinglesand strips are used for handicrafts such asbast shoesand small containers.[5]Historically, the bark was used fortanning.Bark can be heated and the resin collected; the resin is an excellent waterproof glue and useful for starting fires. The thin sheets of bark that peel off young wood contain a waxy resin and are easy to ignite even when wet. The dead twigs are also useful as kindling for outdoor fires.[27]The removal of bark was at one time so widespread thatCarl Linnaeusexpressed his concern for the survival of the woodlands.[28]

Birch brushwood is used forracecourse jumpsandbesombrooms. In the spring, large quantities of sap rise up the trunk and this can be tapped. It contains around 1% sugars and can be used in a similar way tomaple syrup,being drunk fresh, concentrated by evaporation, or fermented into a "wine".[27]

Phytochemicals

[edit]

The outer part of thebarkcontains up to 20%betulin.The main components in the essential oil of thebudsareα-copaene(~10%),germacrene D(~15%), andδ-cadinene(~13%).[29]Also present in the bark are othertriterpenesubstances which have been used in laboratory research to identify its possible biological properties.[30]

Medical uses

[edit]

Betula Verrucosa
Clinical data
Trade namesItulatek
Routes of
administration		Sublingual
ATC code
Legal status
Legal status
  • CA:Rx-only / Schedule D[31]
Identifiers
DrugBank
UNII

Standardized allergen extract, white birch, sold under the brand nameItulatek,isindicatedfor the treatment of allergy to tree pollen from birch, alder and/or hazel and have allergic rhinitis (with or without conjunctivitis).[32][33]

The combination ofBetula pendula/Betula pubescensis used to treatepidermolysis bullosa.[34]The combination of these is also used to make Episalvan gel, which is used to treat wounds in upper layers of the skin.[1]

Leaf extracts ofBetula pendulahave been used to treat bothrheumatoid arthritisandosteoarthritis.The extracts inhibit cell growth and cell division of the activatedT lymphocytesby inducing apoptosis in the cell. This causes a decrease in inflammation caused by arthritis.[35]

Betula pendula and Betula pubescens have the potential to treat cancer because of anti-carcinogenic properties. These buds contain stantin and cirsimaritin. Santin is a flavonol that expresses anti-inflammatory characteristics, which suppresses genes associated with cancer. Both santin and cirsimaritin induceapoptosisof cancer cells.[2]Betula pendulabark extracts inhibit growth of in vitro malignant human cell lines: skin epidermoid carcinoma, ovarian carcinoma, cervix adenocarcinoma, and breast adenocarcinoma.Betula pendulabark extract is also effective for treatingactinic keratosis.[36]

Cultivation

[edit]
B. pendula'Laciniata'

Successful birch cultivation requires a climate cool enough for at least the occasional winter snowfall. As they are shallow-rooted, they may require water during dry periods. They grow best in full sun planted in deep, well-drained soil.[37]

Cultivars and varieties

[edit]
  • 'Carelica' or "curly birch"is calledvisakoivuin Finland. The wood is hard andburledthroughout; it is prized for its decorative appearance and is used in wood-carving and as veneer.[38]
  • 'Laciniata'agm[39](commonly misidentified as'Dalecarlica') has deeply incised leaves and weeping branches
  • 'Purpurea' has dark purple leaves[40]
  • 'Tristis'agm[41]has an erect trunk with weeping branchlets
  • 'Youngii' has dense, twiggy, weeping growth with no central leader and requires being grafted onto a standard stem of normal silver birch.[42]

The cultivars markedagmabove have gained theRoyal Horticultural Society'sAward of Garden Merit.

Betula pendulainTromsøin May,Northern Norway.

References

[edit]
  1. ^abcdefStritch L, Shaw K, Roy S, Wilson B (2014)."Betula pendula".IUCN Red List of Threatened Species.2014:e.T62535A3115662.doi:10.2305/IUCN.UK.2014-3.RLTS.T62535A3115662.en.Retrieved12 November2021.
  2. ^European white birch,TD Tree Bee
  3. ^English Names for Korean Native Plants(PDF).Pocheon:Korea National Arboretum.2015. p. 373.ISBN978-89-97450-98-5.Archived fromthe original(PDF)on 25 May 2017.Retrieved26 January2017– viaKorea Forest Service.
  4. ^What's Wrong With Your Birch?Calgary Herald, 29 June 2010
  5. ^abcdefVedel H, Lange J (1960).Trees and Bushes.Methuen. pp.141–143.ISBN978-0-416-61780-1.
  6. ^abVakkari P (2009)."Silver birch (Betula pendula) "(PDF).EUFORGEN Technical Guidelines for Genetic Conservation and Use.Archived fromthe original(PDF)on 18 January 2017.Retrieved17 January2017.
  7. ^Ranpal S, Sieverts M, Wörl V, Kahlenberg G, Gilles S, Landgraf M, et al. (July 2022)."Is Pollen Production of Birch Controlled by Genetics and Local Conditions?".International Journal of Environmental Research and Public Health.19(13): 8160.doi:10.3390/ijerph19138160.PMC9266428.PMID35805818.
  8. ^abcdFeatherstone AW."Silver birch, downy birch".Trees for Life.Retrieved28 May2014.
  9. ^"Betula pendula".Germplasm Resources Information Network.Agricultural Research Service,United States Department of Agriculture.Retrieved29 May2014.
  10. ^ab"Silver birch:Betula pendula".Forestry Commission. Archived fromthe originalon 29 May 2014.Retrieved28 May2014.
  11. ^ab"European White Birch –Betula pendula"(PDF).USDA Forest Service. 1 September 2006.Retrieved29 May2014.
  12. ^Diamond J, Browning M, Williams A, Middleton J (2003)."Lack of Evidence for Impact of the European White Birch,Betula pendula,on the Hydrology of Wainfleet Bog, Ontario ".Canadian Field-Naturalist.117(3): 393.doi:10.22621/cfn.v117i3.741.
  13. ^abcd"Betula pendulaRoth ".Plants of the World Online.Royal Botanical Gardens Kew.Retrieved28 October2018.
  14. ^abHunt D, ed. (1993). "Betula".Proceedings of the IDS Betula Symposium 2–4 October 1992.International Dendrology Society. p. 51.ISBN0-9504544-5-1.
  15. ^OECD (2008).Novel Food and Feed Safety SET 1: Safety Assessment of Transgenic Organisms OECD Consensus Documents Volumes 1 and 2.OECD Publishing. p. 58.ISBN978-92-64-05346-5.
  16. ^Anderberg A (14 October 1999)."Betula pendulaRoth ".Den virtuella floran.Naturhistoriska riksmuseet.Retrieved29 May2014.
  17. ^Govaerts R (1996). "Proposal to reject the nameBetula alba(Betulaceae) ".Taxon.45:697–698.doi:10.2307/1224262.JSTOR1224262.
  18. ^Shaw K, Roy S, Wilson B (2016)."Betula pendulasubsp.pendula".IUCN Red List of Threatened Species.2014:e.T194831A2363997.doi:10.2305/IUCN.UK.2014-3.RLTS.T194831A2363997.en.
  19. ^Setälä H, Huhta V (1991). "Soil Fauna IncreaseBetula pendulaGrowth: Laboratory Experiments With Coniferous Forest Floor ".Ecology.72(2): 665–671.Bibcode:1991Ecol...72..665S.doi:10.2307/2937206.JSTOR2937206.
  20. ^Robinson GS, Ackery PR, Kitching IJ, Beccaloni GW, Hernández LM (2023)."HOSTS – a Database of the World's Lepidopteran Hostplants [Data set]".London, England: Natural History Museum.doi:10.5519/havt50xw.Retrieved29 May2014.
  21. ^Brändle M, Brandl R (2001)."Species richness of insects and mites on trees: expanding Southwood".Journal of Animal Ecology.70(3): 491–504.Bibcode:2001JAnEc..70..491B.doi:10.1046/j.1365-2656.2001.00506.x.
  22. ^"Birch, downy (Betula pubescens) ".Woodland Trust. Archived fromthe originalon 20 February 2019.Retrieved10 May2016.
  23. ^"Dieback of birch".Forestry Commission.Retrieved10 May2016.
  24. ^Boratynski A (1998), "Betula oycoviensisin IUCN 2009 ",IUCN Red List of Threatened Species. Version 2009.1,International Union for Conservation of Nature and Natural Resources
  25. ^Anttila K (2005)."Suomen kansallistunnukset (Finland's national emblems)".Retrieved30 May2014.
  26. ^"Perinteinen saunavihta (Traditional sauna vihta)"(in Finnish). Visit sauna. Archived fromthe originalon 2 November 2014.Retrieved30 May2014.
  27. ^abCox MD."Firewood types: silver birch".WoodstoveWizard.Retrieved29 May2014.
  28. ^Lindahl J (9 January 2011)."Bark Bread is back".Nordic Wellbeing.Retrieved21 July2011.
  29. ^Demirci B, Paper DH, Demirci F, Can Başer KH, Franz G (December 2004)."Essential Oil of Betula pendula Roth. Buds".Evidence-Based Complementary and Alternative Medicine.1(3): 301–303.doi:10.1093/ecam/neh041.PMC538512.PMID15841263.
  30. ^E Kovac-Besović E, Durić K, Kalodera Z, Sofić E (February 2009)."Identification and isolation of pharmacologically active triterpenes in Betuale cortex, Betula pendula Roth., Betulaceae".Bosnian Journal of Basic Medical Sciences.9(1): 31–38.doi:10.17305/bjbms.2009.2853.PMC5645545.PMID19284392.
  31. ^"ITULATEK: Standardized Allergen Extract, White Birch (Betula Verrucosa)"(PDF).Pdf.hres.ca.Retrieved8 June2022.
  32. ^"Regulatory Decision Summary – Itulatek".Health Canada.23 October 2014.Retrieved7 June2022.
  33. ^"Itulatek Product information".Health Canada.25 April 2012.Retrieved7 June2022.
  34. ^"Filsuvez EPAR".European Medicines Agency(EMA).13 April 2022.Archivedfrom the original on 6 July 2022.Retrieved6 July2022.Text was copied from this source which is copyright European Medicines Agency. Reproduction is authorized provided the source is acknowledged.
  35. ^Gründemann C, Gruber CW, Hertrampf A, Zehl M, Kopp B, Huber R (July 2011). "An aqueous birch leaf extract of Betula pendula inhibits the growth and cell division of inflammatory lymphocytes".Journal of Ethnopharmacology.Immunomodulators.136(3): 444–451.doi:10.1016/j.jep.2011.05.018.PMID21619918.
  36. ^Rastogi S, Pandey MM, Kumar Singh Rawat A (January 2015)."Medicinal plants of the genus Betula--traditional uses and a phytochemical-pharmacological review".Journal of Ethnopharmacology.159:62–83.doi:10.1016/j.jep.2014.11.010.PMC7126499.PMID25449458.
  37. ^Botanica's Trees & Shrubs.San Diego, Calif.: Laurel Glen Publishing. 1999. p. 139.ISBN978-1-57145-649-6.
  38. ^"Betula pendulavar. carelica – curly birch ".Arboretum Mustila. 24 April 2013. Archived fromthe originalon 18 December 2014.Retrieved12 November2014.
  39. ^"Betula pendula'Laciniata'".RHS.Retrieved12 April2020.
  40. ^"RHS Plant Selector –Betula pendula'Purpurea'".Royal Horticultural Society.Retrieved12 November2014.
  41. ^"Betula pendula'Tristis'".RHS.Retrieved12 April2020.
  42. ^"RHS Plant Selector –Betula pendula'Youngii'".Royal Horticultural Society.Retrieved12 November2014.
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