Salix fragilis (
Crack Willow) is a species of
willowWillows, sallows, and osiers form the genus Salix, around 400 species of deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions of the Northern Hemisphere...
native to
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
and western
AsiaAsia is the world's largest and most populous continent, located in the eastern and northern hemispheres. It covers 8.6% of the earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population.Asia is traditionally defined as part of the...
, usually growing beside rivers.
It is a medium-sized to large
deciduousDeciduous means falling off at maturity or tending to fall off and is typically used in reference to trees or shrubs that lose their leaves seasonally and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
treeA tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
, which grows rapidly to 10–20 m (rarely to 29 m) tall, with a trunk up to 1 m diameter and an irregular, often leaning crown. The
barkBark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
is grey-brown, coarsely fissured in older trees. The
leavesIn botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. There is continued debate about whether the flatness of leaves evolved to expose the chloroplasts to more light or to increase the absorption of carbon dioxide. In...
are bright green, 9-15 cm long and 1.5-3 cm wide, with a finely serrated margin; they are very finely hairy at first in spring, but soon become hairless.
Salix fragilis (
Crack Willow) is a species of
willowWillows, sallows, and osiers form the genus Salix, around 400 species of deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions of the Northern Hemisphere...
native to
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
and western
AsiaAsia is the world's largest and most populous continent, located in the eastern and northern hemispheres. It covers 8.6% of the earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population.Asia is traditionally defined as part of the...
, usually growing beside rivers.
It is a medium-sized to large
deciduousDeciduous means falling off at maturity or tending to fall off and is typically used in reference to trees or shrubs that lose their leaves seasonally and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
treeA tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
, which grows rapidly to 10–20 m (rarely to 29 m) tall, with a trunk up to 1 m diameter and an irregular, often leaning crown. The
barkBark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
is grey-brown, coarsely fissured in older trees. The
leavesIn botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. There is continued debate about whether the flatness of leaves evolved to expose the chloroplasts to more light or to increase the absorption of carbon dioxide. In...
are bright green, 9-15 cm long and 1.5-3 cm wide, with a finely serrated margin; they are very finely hairy at first in spring, but soon become hairless. The
flowerA flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds...
s are produced in
catkinA catkin or ament is a slim, cylindrical flower cluster, with inconspicuous or no petals, usually wind-pollinated but sometimes insect pollinated . They contain many, usually unisexual flowers, arranged closely along a central stem which is often drooping...
s in early spring, and pollinated by
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
s. They are
dioeciousPlant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
, with male and female catkins on separate trees; the male catkins are 4–6 cm long, the female catkins also 4–6 cm long, with the individual flowers having either one or two nectaries.
The variety
Salix fragilis var.
decipiens (Hoffm.) K.Koch occurs frequently with the type; it is a smaller
shrubA shrub or bush is a horticultural rather than strictly botanical category of woody plant, distinguished from a tree by its multiple stems and lower height, usually less than 5-6 m tall. A large number of plants can be either shrubs or trees, depending on the growing conditions they experience...
by tree, rarely exceeding 5–7 m tall, with completely hairless leaves up to 9 cm long and 2–3 cm broad. According to some botanists, it is a distinct species (treated as
Salix decipiens Hoffm.), with, in this view,
S. fragilis then being a hybrid between
Salix decipiens and
Salix alba. Some other botanists regard
Salix decipiens as itself being a hybrid between
Salix fragilis and
Salix triandraSalix triandra is a species of willow native to Europe and western and central Asia, from southeastern England east to Lake Baikal, and south to Spain and the Caucasus and Alborz mountains...
. There is little evidence to support either of these suggestions.
It readily forms natural hybrids with White Willow
Salix alba, the hybrid being named
Salix × rubens Schrank.
Ecology
The name derives from the
twigTwigs are critically important in identification of trees, shrubs and vines, especially in wintertime. The buds on the twig are an important diagnostic characteristic, as are the abscission scars where the leaves have fallen away...
s which break off very easily and cleanly at the base with an audible crack. The broken twigs and branches take root readily, enabling the species to colonise new areas, where the broken twigs fall into rivers and can be carried some distance downstream. It is particularly adept at colonising new riverside sandbanks formed after
floodA flood is an overflow or accumulation of an expanse of water that submerges land. In the sense of "flowing water", the word may also be applied to the inflow of the tide....
s.
Cultivation and uses
The
cultivarA cultivar is a cultivated plant that has been selected and given a unique name because of desired characteristics; it is usually distinct from similar plants and when propagated it retains those characteristics....
Salix fragilis 'Russelliana' (syn.
S. fragilis var.
russelliana (Sm.) Koch) is by far the commonest clone of Crack Willow in
Great BritainGreat Britain is an island lying to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island. With a population of about 59.6 million people, it is the third most populated island on Earth. Great Britain is surrounded by over 1000 smaller...
and
IrelandIreland is the third-largest island in Europe and the twentieth-largest island in the world. It lies to the north-west of continental Europe and is surrounded by hundreds of islands and islets. To the east of Ireland, separated by the Irish Sea, is the island of Great Britain...
, very easily propagated by cuttings. It is a vigorous tree commonly reaching 20–25 m tall, with leaves up to 15 cm long. It is a female clone.