Editing Betula pendula (section)

==Description==
[[File:Illustration Betula pendula0.jpg|thumb|left|upright|Silver birch]]
[[File:B. pendula, Koivu Birch, end of August 2.jpg|thumb|right|upright|Silver birch has often pendulous twigs, after which the tree has received its scientific name.]]
The silver birch typically reaches {{convert|15|to|25|m|ft|0|abbr=on}} tall (exceptionally up to {{convert|31|m|ft|abbr=on}}),<ref name=Vedel/> with a slender trunk usually under {{convert|40|cm|in|0|abbr=on}} 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 related [[paper 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 whitish [[resin]] warts and the twigs are slender, hairless, and often [[wikt:pendulous|pendulous]]. The buds are small and sticky, and development is [[sympodial]] – the terminal bud dies away and growth continues from a lateral bud. The species is [[monoecious]] with male and female catkins found on the same tree.<ref name=Vakkari09>{{cite journal| vauthors = Vakkari P |title=Silver birch (''Betula pendula'')|date=2009|journal=EUFORGEN Technical Guidelines for Genetic Conservation and Use|url=http://www.euforgen.org/fileadmin/templates/euforgen.org/upload/Publications/Technical_guidelines/1372_Silver_birch__Betula_pendula_.pdf|access-date=17 January 2017|archive-url=https://web.archive.org/web/20170118051714/http://www.euforgen.org/fileadmin/templates/euforgen.org/upload/Publications/Technical_guidelines/1372_Silver_birch__Betula_pendula_.pdf|archive-date=18 January 2017|url-status=dead}}</ref> Some [[Shoot (botany)|shoot]]s are long and bear the male [[catkin]]s at 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.<ref name=Vedel/>

The [[leaf|leaves]] have short, slender stalks and are {{convert|3|to|7|cm|in|1|abbr=on}} 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.<ref>{{cite journal | vauthors = Ranpal S, Sieverts M, Wörl V, Kahlenberg G, Gilles S, Landgraf M, Köpke K, Kolek F, Luschkova D, Heckmann T, Traidl-Hoffmann C, Büttner C, Damialis A, Jochner-Oette S | title = Is Pollen Production of Birch Controlled by Genetics and Local Conditions? | journal = International Journal of Environmental Research and Public Health | volume = 19 | issue = 13 | page = 8160 | date = July 2022 | pmid = 35805818 | pmc = 9266428 | doi = 10.3390/ijerph19138160 | doi-access = free }}</ref> The small, 1- to 2-mm winged [[seed]]s ripen in late summer on pendulous, cylindrical catkins {{convert|2|to|4|cm|in|1|abbr=on}} long and {{convert|7|mm|1|abbr=on}} 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.<ref name=Vedel/><ref name=tfl/>

Silver birch can easily be confused with the similar [[downy 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 of [[genetic structure]], the trees are quite different, but do, however, occasionally [[Hybridization (biology)|hybridize]].<ref name=Vakkari09/>
[[File:Betula pendula - Childwall Woods & Fields 01.jpg|thumb|upright|''Betula pendula'' silver birch catkins and leaves, Childwall Woods & Fields, [[Merseyside]]]]