Salix alba | |
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White Willow foliage; note white undersides of leaves | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Malpighiales |
Family: | Salicaceae |
Genus: | Salix |
Species: | S. alba |
Binomial name | |
Salix alba | |
Distribution map |
Salix alba, the white willow, is a species of willow native to Europe and western and central Asia. [2] [3] The name derives from the white tone to the undersides of the leaves.
It is a medium to large deciduous tree growing up to 10–30 m tall, with a trunk up to 1 m diameter and an irregular, often-leaning crown. The bark is grey-brown and is deeply fissured in older trees. The shoots in the typical species are grey-brown to green-brown. The leaves are paler than most other willows because they are covered with very fine, silky white hairs, in particular on the underside; they are 5–10 cm long and 0.5–1.5 cm wide. The flowers are produced in catkins in early spring and are pollinated by insects. It is dioecious, with male and female catkins on separate trees; the male catkins are 4–5 cm long, the female catkins 3–4 cm long at pollination, lengthening as the fruit matures. When mature in midsummer, the female catkins comprise numerous small (4 mm) capsules, each containing numerous minute seeds embedded in silky white hairs, which aids wind dispersal. [2] [3] [4]
Like all willows, Salix alba is usually to be found in wet or poorly-drained soil at the edge of pools, lakes or rivers. Its wide-spreading roots take up moisture from a large surrounding area. [5]
White willows are fast-growing but relatively short-lived, being susceptible to several diseases, including watermark disease caused by the bacterium Brenneria salicis (named because of the characteristic 'watermark' staining in the wood; syn. Erwinia salicis) and willow anthracnose, caused by the fungus Marssonina salicicola . These diseases can be a serious problem on trees grown for timber or ornament.
It readily forms natural hybrids with crack willow Salix fragilis , the hybrid being named Salix × rubens Schrank. [2]
Several cultivars and hybrids have been selected for forestry and horticultural use: [2] [3]
The following have received the Royal Horticultural Society's Award of Garden Merit [6]
The wood is tough, strong, and light in weight, but has minimal resistance to decay. The stems (withies) from coppiced and pollarded plants are used for basket-making. Charcoal made from the wood was important for gunpowder manufacture. The bark tannin was used in the past for tanning leather. [2] [3] The wood is used to make cricket bats.
S. alba wood has a low density and a lower transverse compressive strength. This allows the wood to bend, which is why it can be used to make baskets. Willow bark contains indole-3-butyric acid, which is a plant hormone stimulating root growth; willow trimmings are sometimes used to clone rootstock in place of commercially synthesized root stimulator. [12] It is also used for ritual purposes by Jews on the holiday of Sukkot. [13]
Willow (of unspecified species) has long been used by herbalists for various ailments, although it is a myth that they attribute to it any analgesic effect. [14] One of the first references to White Willow specifically was by Edward Stone, of Chipping Norton, Oxfordshire, England, in 1763. He 'accidentally' tasted the bark and found it had a bitter taste, which reminded him of Peruvian Bark (Cinchona), which was used to treat malaria. After researching all the 'dispensaries and books on botany,' he found no suggestion of willow ever being used to treat fevers and decided to experiment with it himself. Over the next seven years he successfully used the dried powder of willow bark to cure 'agues and intermittent fevers' of around fifty people, although it worked better when combined with quinine. [15]
Stone appears to have been largely ignored by the medical profession and herbalists alike. There are reports of two pharmacists using the remedy in trials, but there is no evidence that it worked. [16] By the early 20th century, Maud Grieve, an herbalist, did not consider White Willow to be a febrifuge. Instead, she describes using the bark and the powdered root for its tonic, antiperiodic and astringent qualities and recommended its use in treating dyspepsia, worms, chronic diarrhoea and dysentery. [17] She considered tannin to be the active constituent.
An active extract of the bark, called salicin, after the Latin name Salix, was isolated to its crystalline 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. Salicylic acid is a chemical derivative of salicin and is widely used in medicine. Acetylsalicylic acid (aspirin) is, however, a chemical that does not occur in nature and was originally synthesised from salicylic acid [18] extracted from Meadowsweet, and is not connected to willow. [19]
Willows, also called sallows and osiers, of the genus Salix, comprise around 350 species of typically deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions.
Betula pendula, commonly known as silver birch, warty birch, European white birch, or East Asian white birch, is a species of tree in the family Betulaceae, native to 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 the European white birch or weeping birch and is considered invasive in some states in the United States and parts of Canada. The tree can also be found in more temperate regions of Australia.
Betula pubescens, commonly known as downy birch and also as moor birch, white birch, European white birch or hairy birch, is a species of deciduous tree, native and abundant throughout northern Europe and northern Asia, growing farther north than any other broadleaf tree. It is closely related to, and often confused with, the silver birch, but grows in wetter places with heavier soils and poorer drainage; smaller trees can also be confused with the dwarf birch.
Salix caprea, known as goat willow, pussy willow or great sallow, is a common species of willow native to Europe and western and central Asia.
Salix purpurea, the purple willow, purpleosier willow, or purple osier, is a species of willow native to most of Europe and western Asia north to the British Isles, Poland, and the Baltic States.
Salix × fragilis, with the common names crack willow and brittle willow, is a hybrid species of willow native to Europe and Western Asia. It is native to riparian habitats, usually found growing beside rivers and streams, and in marshes and water meadow channels. It is a hybrid between Salix euxina and Salix alba, and is very variable, with forms linking both parents.
Populus alba, commonly called silver poplar, silverleaf poplar, or white poplar, is a species of poplar, most closely related to the aspens. It is native to a region spanning from the Atlas Mountains of Africa, through most of South and Central Europe, into Central Asia; it has been introduced to many temperate, moist regions worldwide. It grows in moist sites, often by watersides, in regions with hot summers and cold to mild winters.
Salix babylonica is a species of willow native to dry areas of northern China, but cultivated for millennia elsewhere in Asia, being traded along the Silk Road to southwest Asia and Europe.
Salix integra is a species of willow native to north-eastern China, Japan, Korea and the far south-eastern Russia.
Populus tremula is a species of poplar native to cool temperate regions of the Old World.
Salix magnifica is a species of willow in the family Salicaceae. It is endemic to Sichuan in southwestern China, where it grows at high altitudes of 2,100–3,000 m above sea level. It is threatened by habitat loss.
Salix exigua is a species of willow native to most of North America except for the southeast and far north, occurring from Alaska east to New Brunswick, and south to northern Mexico. It is considered a threatened species in Massachusetts while in Connecticut, Maryland, and New Hampshire it is considered endangered.
Salix triandra, with the common names almond willow, almond-leaved willow or black maul willow, is a species of willow native to Europe and Western and Central Asia. It is found from south-eastern England east to Lake Baikal, and south to Spain and the Mediterranean east to the Caucasus, and the Alborz Mountains. It usually grows in riparian habitats, on river and stream banks, and in wetlands.
Salix acutifolia, also known as Siberian violet-willow, long-leaved violet willow or sharp-leaf willow, is a species of flowering plant in the family Salicaceae, native to Russia and eastern Asia. It is a spreading, deciduous shrub or tree, growing to 10 m (33 ft) tall by 12 m (39 ft) wide. The young shoots are deep purple with a white bloom. The leaves are narrow, up to 10 cm (4 in) long. The catkins are produced in early spring, before the leaves. Older bark has a fine, netted pattern.
The Salix Sepulcralis Group is a cultivar group containing all cultivars of hybrids between Salix alba and Salix babylonica. The trees in this group are sometimes referred to as white weeping willow or glaucous weeping willow in reference to the mixed appearance from the parent species. It was first described by L. Simonkai in 1890 from trees growing in Romania. The group contains both weeping and nonweeping cultivars, though the best-known of its cultivars is 'Chrysocoma', the most widely grown weeping tree..
Some of the cultivars are hybrids of S. babylonica var. matsudana 'Tortuosa' and have inherited from its parent the twisted and contorted branches, as well as being more cold-tolerant, as S. babylonica var. matsudana is native to northern China and Korea.
Salix × sepulcralis 'Chrysocoma', or Weeping Golden Willow, is the most popular and widely grown weeping tree in the warm temperate regions of the world. It is an artificial hybrid between S. alba 'Vitellina' and S. babylonica. The first parent provides the frost hardiness and the golden shoots and the second parent the strong weeping habit.
This cross was originally made at the Späth Nursery and was first mentioned in their 1888 nursery catalogue as S. vitellina pendula nova.
Being a cultivar from the Chrysocoma Group, which includes all crosses between S. alba and S. babylonica, it is much hardier and more long-lived than the Babylon Willow. This particular cultivar is easily distinguished from the other Golden Weeping Willow by its androgynous catkins.
Betula utilis, the Himalayan birch, is a deciduous tree native to the Western Himalayas, growing at elevations up to 4,500 m (14,800 ft). The Latin specific epithet utilis means "useful", and refers to the many uses of the different parts of the tree. The white, paper-like bark was used in ancient times as a writing surface for manuscripts of Sanskrit literature. It is still used as paper for the writing of mantras, with the bark placed in an amulet and worn for protection. Selected varieties are used for landscaping throughout the world, even while some areas of its native habitat are being lost due to overuse of the tree for firewood.
Salix alaxensis is a species of flowering plant in the willow family known by the common names Alaska willow and feltleaf willow. It is native to northern North America, where it occurs throughout Alaska and northwestern Canada.
Salix daphnoides, the European violet willow, is a species of plant in the family Salicaceae. It can grow as a large shrub or small tree, normally reaching a height of 6–8 m (20–26 ft), but can grow up to 12 m (39 ft) tall.
Salix euxina, the eastern crack-willow, is a species of flowering plant in the willow family Salicaceae, native from Turkey to the Caucasus. It was first described by I. V. Belyaeva in 2009. It is one of the parents of the common crack-willow, Salix × fragilis.