Silver Birch
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Silver Birch (Betula pendula) is a widespread European birch, though in southern Europe it is only found at higher altitudes. Its range extends into southwest Asia in the mountains of northern Turkey and the Caucasus. The closely related Siberian Silver Birch (B. platyphylla) in northern Asia and Sichuan Birch (B. szechuanica) of central Asia are also treated as varieties of Silver Birch by some botanists, as B. pendula var. platyphylla and B. pendula var. szechuanica respectively (see birch classification).
It is a medium size deciduous tree, typically reaching 15-25 m tall, exceptionally up to 30 m, with a slender crown of arched branches with drooping branchlets. The bark is white, often with black diamond-shaped marks or larger patches at the base. The shoots are rough with small warts, and hairless, and the leaves 3-6 cm long, triangular with a broad base and pointed tip, and coarsely serrated margins. The flowers are wind-pollinated catkins, produced before the leaves in early spring, the small (1-2 mm) winged seeds ripening in late summer on 3-5 cm long catkins.
It is distinguished from the related White Birch (B. pubescens, the other common European birch) in having hairless, warty shoots (downy, without warts in White Birch), and whiter bark often with scattered black fissures (greyer, less fissured, in White Birch). It is also distinguished cytologically, Silver Birch being diploid (with two sets of chromosomes), whereas White Birch is tetraploid (four sets of chromosomes). The two have subtle differences in habitat requirements, with Silver Birch found mainly on dry, sandy soils, and White Birch commoner on wet, poorly drained sites such as clay soils and peat bogs. Many North American texts treat the two species as conspecific (and cause confusion by combining the vernacular name 'White Birch' of one, with the scientific name B. pendula of the other), but they are regarded as distinct species throughout Europe.
It is often planted as a garden and ornamental tree, grown for its white bark and gracefully drooping shoots. In Scandinavia and other regions of northern Europe, it is grown for forestry. It is sometimes used as a pioneer and nurse tree elsewhere.
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