The White Willow is a willow native to Europe, and western and central Asia. It is a large deciduous tree up to 20-30 m tall. The name derives from the leaves, which are paler than most other willows, due to a covering of very fine silky white hairs, particularly on the underside. The leaves are typically 5-10 cm long and 1-1.5 cm wide. The shoots in the typical species are grey-brown to green-brown. The flowers are catkins, produced in early spring.
A number of cultivars and hybrids of White Willow have been selected for forestry and horticulture use:
White Willows are fast-growing, but short-lived, being susceptible to several diseases, including watermark disease caused by the bacterium Erwinia salicis (named because of the characteristic 'watermark' staining in the wood) and willow anthracnose, caused by the fungus Marssonina salicicola. These diseases can be a serious problem on trees grown for timber or ornament.
The active extract of the bark, called salicin, after the Latin name for the White willow (Salix alba), was isolated to its crystaline form in 1828 by Henri Leroux, a French pharmacist, and Raffaele Piria, an Italian chemist, who then succeeded in separating out the acid in its pure state. Salicin is highly acidic when in a saturated solution with water (pH = 2.4), and is called salicylic acid for that reason. This is the precursor to modern aspirin (acetylsalicylic acid).
Бяла върба | Vimetera | Hvid-pil | Silber-Weide | Saule blanc | Schietwilg | Shelgu i bardhë | Vitpil | Верба біла
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