# Horticulture/Salix

Willow :
| Genus: | Salix |
| Family: | Salicaceae |
| Type: | Trees and shrubs |
| Pollination: | Insects |
The willows are deciduous trees and shrubs in the genus Salix, part of the willow family Salicaceae. There are about 350 species in this genus worldwide, found primarily on moist soils in cooler zones in the Northern Hemisphere. Some smaller species may also be known by the common names osier and sallow; the latter name is derived from the same root as the Latin salix.
Some willows, particularly arctic and alpine species, are very small; the Dwarf Willow (Salix herbacea) rarely exceeds 6 cm in height, though spreading widely across the ground.
The Weeping Willow, very widely planted as an ornamental tree, is a cultivar, Salix × sepulcralis 'Chrysocoma', derived from a hybrid between the Chinese Peking Willow and the European White Willow.
Almost all willows take root very readily from cuttings or where broken branches lie on the ground. There are a few exceptions, including the Goat Willow and Peachleaf Willow. One famous example of such growth from cuttings involves the poet Alexander Pope, who begged a twig from a parcel tied with twigs sent from Spain to Lady Suffolk. This twig was planted and thrived, and legend has it that all of England's Weeping Willows are descended from this first one.

## Description

The leaves are deciduous, often elongate but round to oval in a few species, and with a serrated margin. Willows are deciduous with male and female flowers appearing as catkins on different plants; the catkins are produced early in the spring, often before the leaves or as the new leaves open. The fruit is a small capsule containing numerous tiny (0.1 mm) seeds embedded in white down, which assists wind dispersal of the seeds. Willows hybridize freely, and numerous hybrids are known, both naturally occurring and in cultivation.

## Species

| Salix acutifolia - Violet Willow Salix alaxensis - Alaska Willow Salix alba - White Willow Salix alpina - Alpine Willow Salix amygdaloides - Peachleaf Willow Salix arbuscula - Mountain Willow Salix arbusculoides - Littletree Willow Salix arctica - Arctic Willow Salix atrocinerea Salix aurita - Eared Willow Salix babylonica - Peking Willow Salix bakko Salix barrattiana - Barratt's Willow Salix bebbiana - Beaked Willow Salix boothii - Booth Willow Salix bouffordii Salix brachycarpa - Barren-ground Willow Salix cacuminis Salix canariensis Salix candida - Sage Willow Salix caprea - Goat Willow Salix caroliniana - Coastal Plain Willow Salix chaenomeloides Salix chilensis Salix cinerea - Grey Sallow Salix cordata Salix daphnoides Salix discolor - Pussy Willow Salix eastwoodiae - Eastwood's Willow Salix eleagnos Salix eriocarpa Salix eriocephala - Heartleaf Willow Salix exigua - Sandbar Willow Salix foetida Salix fragilis - Crack Willow Salix futura Salix geyeriana Salix gilgiana Salix glauca Salix gooddingii - Goodding Willow Salix gracilistyla Salix hainanica - Hainan Willow Salix helvetica - Swiss Willow Salix herbacea - Dwarf Willow Salix hirsuta Salix hookeriana - Hooker's Willow Salix hultenii Salix humboldtiana - Chile Willow Salix humilis - Upland Willow Salix integra Salix interior Salix japonica Salix jessoensis Salix koriyanagi Salix kusanoi | Salix lanata - Woolly Willow Salix lapponum - Downy Willow Salix lasiandra - Pacific Willow Salix lasiolepsis - Arroyo Willow Salix lucida - Shining Willow Salix magnifica Salix matsudana - Chinese Willow Salix miyabeana Salix mucronata Salix myrtilloides - Swamp Willow Salix myrsinifolia - Dark-leaved Willow Salix myrsinites - Whortle-leaved Willow Salix nakamurana Salix nigra - Black Willow Salix pedicellaris - Bog Willow Salix pentandra - Bay Willow Salix petiolaris - Slender Willow Salix phylicifolia - Tea-leaved Willow Salix planifolia- Planeleaf Willow Salix polaris - Polar Willow Salix pseudo-argentea Salix purpurea - Purple Willow Salix pyrifolia - Balsam Willow Salix reinii Salix repens - Creeping Willow Salix reticulata - Net-leaved Willow Salix retusa Salix rorida Salix rosmarinifolia - Rosemary-leaved Willow Salix rupifraga Salix salicicola Salix schwerinii Salix scouleriana - Scouler's Willow Salix sericea - Silky Willow Salix serissaefolia Salix serissima - Autumn Willow Salix shiraii Salix sieboldiana Salix sitchensis Salix subfragilis Salix subopposita Salix taraikensis Salix tetrasperma Salix thorelii Salix triandra - Almond Willow Salix udensis Salix viminalis - Common Osier Salix vulpina Salix waldsteiniana Salix wallichiana Salix wilmsii Salix woodii Salix yezoalpina Salix yoshinoi |

## Uses

The bark of the willow tree has been mentioned in ancient texts from Assyria, Sumer and Egypt as a remedy for aches and fever, and the Greek physician Hippocrates wrote about its medicinal properties in the 5th century BC. Native Americans across the American continent relied on it as a staple of their medical treatments.
The active extract of the bark, called salicin, 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. Salicin is acidic when in a saturated solution in water (pH = 2.4), and is called salicylic acid for that reason.
In 1897 Felix Hoffmann created a synthetically altered version of salicin (in his case derived from the Spiraea plant), which caused less digestive upset than pure salicylic acid. The new drug, formally Acetylsalicylic acid, was named aspirin by Hoffmann's employer Bayer AG. This gave rise to the hugely important class of drugs known as non-steroidal anti-inflammatory drugs (NSAIDs).

### Other uses

| Agroforestry Basket weaving Biofiltration Biomass energy (bioenergy) Boxes and veneers Charcoal Constructed wetlands Cricket bats Cradle boards Chairs & furniture Dolls, toys, whistles Ecological wastewater treatment systems Energy forestry As part of the four species used on the Jewish holiday of Sukkot. Fibre plants Fish traps Flutes Hedges Land reclamation | Landscaping Living Willow Sculpture Paper Phytoremediation Poles, turnery, tool handles Rope and string Streambank stabilization (bioengineering) Slope stabilization Soil erosion control Soil building Soil reclamation Shelterbelt & windbreak Sweat lodges Tannin Wands, brooms Wattle fences Wattle and daub Wildlife habitat |

## Maintenance

A number of willow species were widely planted in Australia in the past, notably as erosion control measures along watercourses. They are now regarded as an invasive weed and many catchment management authorities are removing them to be replaced with native trees.

## Pests and diseases

| Aphids Melon Aphid, Cotton Aphid: Aphis gossypii Giant Bark Aphid: Longistigma caryae Black Willow Aphid: Pterocomma smithiae Carrot-Willow Aphid Giant Willow Aphid: Tuberolanchus salignus Western Willow Aphid Scale Insects: California Red Scale: Aonidiella aurantii Willow Scurfy Scale: Chionaspis salicis-nigrae Greedy Scale: Hemiberlesia rapax Cottony-Cushion Scale: Icerya purchasi European Fruit Scale: Lecanium corni Terrapin Scale: Lecanium nigrofasciatum Oystershell Scale: Lepidosaphes ulmi Obscure Scale: Melanaspis obscura Cottony Maple Scale: Pulvinaria innumerabilis Black Scale: Saissetia oleae Buckeye Scale: Diaspidiotus aesculi Cottony Grape Scale: Pulvinaria vitis Hoppers: Leafhopper: Macropsis ocellata Bugs: Willow Lace Bug: Corythucha mollicula Thrips Maggots: Willowbeaked Gall Midge: Mayetiola rigidae Pine Cone Gall Midge: Rhabdophaga strobiliodes Beetles: Bronze Poplar Borer: Agrilus granulatus liragus Western Poplar Agrilus: Agrilus granulatus populi Common Willow Agrilus: Agrilus politus Asian Longhorned Beetle: Anoplophora glabripennis Flatheaded Appletree Borer: Chrysobothris femorata Beetles: Chrysomela spp. Mottled Willow Borer: Cryptorhynchus lapathi Willow Flea Beetles: Disonycha Pole Borer: Parandra brunnera Imported Willow Leaf Beetle: Plagiodera versicolora Cottonwood Borer: Plectodera scalator Japanese Beetle: Popillia japonica Willow Flea Beetle: Rhynchaenus rufipes Poplar Borer: Saperda calcarata Bark Beetle: Scolytus shevyrewi Black Twig Borer: Xylosandrus compactus Elm Calligrapha Pacific Willow Leaf Beetle Weevils: Asiatic Oak Weevil: Cyrtepistomus castaneus Willow Flea Weevil | Caterpillars Caterpillar: Dasychira grisefacta Fall Webworm: Hyphantria cunea Gypsy Moth: Lymantria dispar Eastern Tent Caterpillar: Malacosoma americanum Bruce Spanworm: Operophtera bruceata Tentiform Leafminer: Phyllonorycter salicifoliella Tentiform Leafminer: Phyllonorycter nipigron Satin Moth Caterpillar: Stilpnotia salicis Bagworm: Thyridopterix ephemeraeformis Big Poplar Sphinx California Tent Caterpillar: Malacosoma californica Cecropia Moth Hyalophora cecropia Eastern Tiger Swallowtail: Papilio glaucus Hemlock Looper Io Moth: Automeris io Luna Moth: Actias luna Mourning Cloak: Nymphalis antiopa Nevada Buck Moth Omnivorous Loopers: Sabulodes aegrotata, Sabulodes caberata Oneeyed Sphinx Orange Tortrix: Argyrotaenia citrana Polyphemus Moth: Antheraea polyphemus Poplar Tentmaker Redhumped Caterpillar: Schizura concinna Satin Moth: Stilpnotia salicis Sparganothis Leafroller: Sparganothis sulfureana Speckled Green Fruitworm: Orthosia hibisci Twinspot Sphinx Walnut Caterpillar: Datana integerrima Western Tiger Swallowtail Winter Moth: Operophtera brumata Sawflies: Elm Sawfly: Cimbex americana Willow Stemgall Sawflies: Euura spp. Willow Shoot Sawfly: Janus abbreviatus Willow Leafgall Sawfly: Pontania californica Willow Leafgall Sawfly: Pontania pacifica Willow Redgall Sawfly: Pontania proxima Sawfly: Trichiosoma triangulum Sawfly: Trichiosoma viminalis Birch Sawfly Poplar Leaffolding Sawfly Willow Sawfly Wasps: Giant Hornet: Vespa crabro germana Mites: Linden Spider Mite |

## Gallery

* Weeping Willow in Auckland, New Zealand
* Willow catkin
* Willow catkin

## References

* Newsholme, C. (1992). Willows: The Genus Salix. ISBN 0-88192-565-9
* Warren-Wren, S.C. (1992). The Complete Book of Willows. ISBN 0-498-01262-X
* Reference for the story concerning Alexander Pope Extract from the Every day book by William Hone, (1826) quoting "Martyn" and the Saint James's Chronicle (1801).
* Britton, Nathaniel Lord (1913). An Illustrated Flora of the Northern United States and Canada, Volume 1 (second edition ed.). Dover Publications, inc. pp. 591–605. {{cite book}}: |edition= has extra text (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
* Ann Fowler Rhoads and Timothy A. Block (2000). The Plants of Pennsylvania: An Illustrated Manual. Anna Anisko, illustrator. Morris Arboretum, University of Pennsylvania Press. pp. 645–654. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
* Christopher Brickell and Judith D. Zuk (1997). The American Horticultural Society A-Z Encyclopedia of Garden Plants. DK Publishing. pp. 923–925. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
* Staff of the L. H. Bailey Hortorium (1976). Hortus Third: A Concise Dictionary of Plants Cultivated in the United States and Canada. Cornell University Press. pp. 955–998. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
* Pirone, Pascal P. Diseases & Pests of Ornamental Plants. pp. 476–479. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
* Cranshaw, Whitney (2004). Garden Insects of North America. Princeton University Press. p. 619. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
* Salix alba at plants for a future
* Salix purpurea at plants for a future
* 1911 Encyclopaedia Britannica
* Salix caroliniana images at bioimages.vanderbilt.edu
* Salix nigra images at bioimages.vanderbilt.edu
* Salix humboldtiana or Chilean willow images
* ↑ http://www.uab.edu/english/hone/etexts/edb/day-pages/221-aug09.html
* ↑ http://www.dse.vic.gov.au/dpi/nreninf.nsf/childdocs/-1C62D26CD3AF6FE44A2568B300051289-8E21A59E53B35BEFCA256BC80005C14F-E1EB709D7DCE1BC9CA256F070003E8D8-FAC3FFA202EA6384CA256BCF000AD522?open
* ↑ http://www.hoadley.net/cremer/willows/docs/WillowInBiodiversity.pdf