Trees & Shrubs – Salix – The Willows – including The Weeping Willow (Salix babylonica)
Willows, also called 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. Most species are known as willow, but some narrow-leaved shrub species are called osier, and some broader-leaved species are referred to as sallow (from Old English sealh, related to the Latin word salix, willow).
The RHS list the following species as native to the UK
Salix alba (white willow): 25m, very fast-growing
Salix fragilis (crack willow): 25m, coarse tree for damp areas
Salix caprea (goat willow): 10m, yellow catkins on male trees
Salix pentandra (bay willow): 10m, showy catkins on male trees
Salix triandra (almond willow): 10m, long catkins on male trees
Salix cinerea (grey willow): 6m, silky male catkins
Salix viminalis (osier): 6m, fast-growing, attractive male catkins
Salix myrsinifolia (dark-leaved willow): 4m, tolerates wet, hairy young stems
Salix phylicifolia (tea-leaved willow): 4m, glossy dark winter stems
Salix purpurea (purple willow): 5m, attractive winter stems
Salix aurita (eared willow): 3m, prefers acid soil, red/brown stems
Salix herbacea (dwarf willow): 10cm, forms a creeping mat
Salix lanata AGM (woolly willow): 1m, small alpine species, grey leaves
Salix lapponum (downy willow): 1m, small dense shrub, grey leaves
Salix myrsinites (whortle-leaved willow): 50cm, carpeting species, shiny leaves
Salix repens (creeping willow): 60cm, attractive male catkins
Salix reticulata AGM (net-leaved willow): 8cm, dwarf, mat-forming species
The most famous of the Salix family the “Weeping Willow” is an early Chinese cultivar selection including the original weeping willow, Salix babylonica ‘Pendula’, in which the branches and twigs are strongly pendulous, which was presumably spread along ancient trade routes. These distinctive trees were subsequently introduced into England from Aleppo in northern Syria in 1730. These plants are all females, readily propagated vegetatively, and capable of hybridizing with various other kinds of willows, but not breeding true from seed.
— Des McKenzie (@McKenzie6593) May 3, 2016
Two cultivated hybrids between pendulous Salix babylonica and other species of Salix willows also have pendulous branchlets, and are more commonly planted than S. babylonica itself: Salix × pendulina, a hybrid with S. babylonica accepted as the female parent.
Salix babylonica (Babylon willow) has many cultivars, including:
- ‘Babylon’ (synonym: ‘Napoleon’) is the most widely grown cultivar of S. babylonica, with its typical weeping branches.
- ‘Crispa’ (synonym: ‘Annularis’) is a mutant of ‘Babylon’, with spirally curled leaves.
Various cultivars of Salix matsudana (Chinese willow) are now often included within Salix babylonica, treated more broadly, including:
- ‘Pendula’ is one of the best weeping trees, with a silvery shine, hardier, and more disease resistant.
- ‘Tortuosa’ is an upright tree with twisted and contorted branches.
Yet other weeping willow cultivars are derived from interspecific Salix hybrids, including S. babylonica in their parentage. The most widely grown weeping willow cultivar is Salix × sepulcralis ‘Chrysocoma’, with bright yellowish branchlets.
The RHS also list the following naturally occurring hybrids.
Salix × alopecuroides
Salix × calodendron
Salix × capreola
Salix × fruticosa
Salix × latifolia
Salix × lauriana
Salix × lintonii
Salix × meyeriana
Salix × mollisima
Salix × multinervis
Salix × pontederiana
Salix × reichardtii
Salix × rubens
Salix × rubra
Salix × sericans
Salix × smithiana
Salix × stipularis
The Willows (Salix). Edward Step had this to say about the Willow in his Wayside and Woodland Trees.
There is not in the whole of the British flora another genus of plants that presents such difficulties of identification as the genus Salix. Even so hardened a botanist as Sir J. D. Hooker, in reviewing the tangle of species, varieties (natural and cultivated), and hybrids, is so far stirred from his ordinary composure that he stigmatizes it as a “troublesome genus.” When Sir Joseph chose that mild adjective he was at Kew surrounded by the national herbaria and with nicely labelled living plants at hand for comparison. What, then, can the rambling nature-lover hope to do with the Willows he comes across one at a time, without much chance of comparing? He must be content to follow the “lumpers,” who group a number of these uncertain forms under the name of a species to which they have evident relationship. When he has mastered the distinctions between these aggregate species, it will be early enough to attempt the segregation of the forms and varieties under each.
In their natural condition Willows are graceful and picturesque, but a large number of the examples met with in our rambles have been so altered for commercial reasons as to be more grotesque than beautiful. It is not the timber-man who is responsible this time, for a pollard Willow, though it produces a shock-head of long slender shoots, suitable for basket-rods, lets in moisture at the top of the bole, and the wood is more or less decayed and worthless. Only four of our native Willows can be regarded as timber trees. These are the White Willow, the Crack Willow, the Bedford Willow, and the Sallow. Like the Poplars, their growth is very rapid, and their wood is consequently light, but it has the advantage of Poplar-wood in being tougher, and therefore serving for purposes where Poplar is of no value. In the present day the growers of straight-boled Willows find their best market among the makers of cricket-bats. A good deal of it is also cut into thin strips for plaiting into chip-hats and hand-baskets. The Osier is grown in extensive riverside beds for the production of long pliant shoots for the basket-weavers; though many of the so-called Osier-rods are really stool-shoots from Willows that have been pollarded, or whose leading shoot has never been allowed to grow. On those parts of our coast where the crab and lobster fishery is pursued, a regular supply of such shoots for weaving into “pots” and “hullies” is a necessity, and a “withy bed” will usually be found on some valley stream near, or on a damp terrace halfway up the cliffs.
Bole of Crack Willow.
The bark of the tree Willows has long been known to be rich in an alkaloid called salicine, which has tonic and astringent properties, and has often been used instead of quinine, though it is not nearly so powerful as the Peruvian drug. The bark is also used for tanning.
The association of the Willow with sadness is very old, but there does not appear to be any satisfactory reason for it—certainly to contemplate a naturally-grown Willow that grows on the edge of a limpid stream, in which its graceful shoots and slender leaves are reflected, does not suggest sad thoughts to the average healthy mind. The association is chiefly with maidens forsaken by their false lovers, as indicated by Shakespeare when he makes Desdemona say—
The Crack Willow or Withy (Salix fragilis) is one of the two most considerable of our tree Willows. In good soil it will in twenty years attain nearly its full height, which is eighty or ninety feet. Its bole sometimes has a girth of twenty feet. Its smooth, polished shoots afford the best ready means of distinguishing it, for instead of their base pointing to the centre of the trunk as in other trees, they grow obliquely, so that the shoots frequently cross each other. They are both tough and pliant, but if struck at the base they readily break off. This character explains the names Crack Willow and fragilis. The leaves are lance-shaped, three to six inches long, smooth, with glandular teeth, pale or glaucous on the underside, and with half-heart-shaped stipules, which, however, are soon cast off. As we have already indicated under the head of Poplars, the male and female catkins of the Willows are borne by different trees. In the case of the Crack Willow, the male catkins are an inch or two long, proportionately stout, each flower bearing two stamens (occasionally three, four, or five). The female catkin is more slender, the flowers each containing a smooth ovary, ending in a short style that divides into two curved stigmas. The catkins appear in April or May. Although, like most of the Willows, this species is fond of cold, wet soil in low situations, it is not restricted to the plains. In Northumberland it is found at 1300 feet above the sea. Its northward range extends as far as Ross-shire, but it is a doubtful native in both Scotland and Ireland.
The Bedford Willow (S. russelliana) is believed to be a hybrid between S. fragilis and S. alba. It grows to a height of fifty feet, with a girth of twelve feet. The leaves are more slender than those of S. fragilis, taper to a point at each end, and are very smooth on both sides. It occurs in swampy woods.
Flowers of White Willow.
The White Willow (Salix alba) is so called from the appearance of the leaves as the light is reflected from their silky surfaces, which are alike above and below. It is a tree from sixty to eighty feet high, with a girth of twenty feet, covered with thick and deeply fissured bark. The leaves are from two to four inches long, of a narrow elliptical shape. In the typical form the twigs are olive-coloured, but in the variety vitellina (known as the Golden Willow) these are yellow or reddish. In the variety cærulea the old leaves become quite smooth above, but retain the glaucous appearance of the underside. The White Willow is found as far north as Sutherlandshire, but although it is believed to be an indigenous species, most of the modern specimens appear to have been planted. It affords good timber, and the bark is almost equal to that of Oak for tanning. A great number of the old Willows met with in our rambles are partially decayed, a condition frequently the result of lopping large branches, for the wound never heals, and decay setting in at that point, extends down the bole. Upon such decaying specimens one may often find one of the most handsome of our native beetles—the Musk-beetle, with long, slender body and long antennæ, all coloured in dark golden green, and diffusing the aroma of a rose.
Bole of White Willow.
The Almond-leaved or French Willow (Salix triandra) is a small tree about twenty feet high, distinguished by its bark being thrown off in flakes. Its slender lance-shaped leaves are smooth green above and glaucous beneath, two to four inches long, and with half-heart-shaped stipules. The male flowers offer another distinguishing mark in their stamens being three in number. Its habitats are the banks of rivers and streams, and in Osier-beds. It is extensively grown on account of the long, straight shoots produced from the stump when the tree is cut down, which are of great use in wicker-work.
The Bay-leaved Willow (Salix pentandra) is met with either as a small upright tree about twenty feet high, or as a shrub eight feet high. Its oval or elliptical leaves are rich green, smooth and sticky on the upper surface, and give out a pleasant fragrance like those of the Bay-tree; they vary from an inch to four inches long, and they may or may not bear stipules, but if these are present they will be egg-shaped or oblong. The stamens are normally five in each flower, but they vary up to twelve. This is reputed to be of all our Willows the latest to flower. A line drawn through York, Worcester, and North Wales will give roughly its southward range as a native species. South of that line it has been planted; north of it to the Scottish border it is a native. It has been found growing at a height of 1300 feet in Northumberland.
Bole of Bay-leaved Willow.
The Sallow (Salix caprea) is the only other species that can properly be considered as a tree, as it attains to a height of thirty feet, though fifteen to twenty feet is a more common measurement. Its usually egg-shaped leaves vary from almost round to elliptical or lance-shaped, and from two to four inches in length. In the typical form, which occurs chiefly in woods, dry pastures, and hedgerows, they are broad, smooth, and dull-green above, covered with soft white down beneath; the stipules half-kidney-shaped. This is the earliest of all our Willows to flower, and the gold (male) and silver (female) catkins are put out before the leaves. In the country, within a few miles of the larger cities, this can hardly be a desirable species to plant, for on the Sunday before Easter thousands who at no other period exhibit any strong religious tendency journey out to pick some “Palm,” as they designate the Sallow bloom, and the rough pruning the Sallows then get must in many cases be disastrous. He who imagines that insect life is suspended until spring is on the verge of summer should visit the woods when the Sallow is in bloom; he will be astonished at the swarms of bees and moths that are collecting the abundant pollen or sipping the nectar provided for them. Before the bright catkins can be seen the locality of the tree may be known by the loud hum produced by hundreds of pairs of wings. The all but invariable rule among the Willows—as among Oaks, Beech, Birch, Hazel, and Pines—is to depend upon the wind for the transfer of pollen from one tree to the stigmas of another of the same species, but in the Sallow we find a breaking away from what was doubtless the primitive arrangement in all flowering plants, by the bribing with honey of more reliable and less wasteful winged carriers.
The Gray Sallow (Salix cinerea) is really a sub-species of S. caprea. It has a liking for moister places than the type, or perhaps it would be more accurate to say that its growth in moister situations has brought about the differences by which it is separated from the parent form. These points are, briefly—the buds and twigs are downy, the leaves smaller and proportionately narrower, the upper surface downy, grey-green beneath; the anthers of the male pale yellow, the capsule of the female smaller.
The Eared Sallow (S. aurita) is probably also only another form of S. caprea, distinguished by its small, bushlike proportions (two to four feet high), long branches and red twigs; its small wrinkled leaves, which are usually less than two inches long, are of an almost oblong shape, downy beneath, and with large ear-shaped stipules. Its likeness is much closer to S. cinerea than to the type; it is fond of damp copses and moist places on heaths, where it may be found at considerable elevations. In the Highlands it ascends to 2000 feet.
There are Willows of dwarf habit, some with long straggling branches and more or less prostrate stems, that grow upon heaths. Each has a name under which it has at some time or other been ranked as a distinct species, just as the forms of Bramble and Rose have been. The differences between them are minute, and of little interest save to the advanced scientific botanist, who with his dried specimens spread before him often detects subtle distinctions not apparent to the outdoor student of the living plant. For the purposes of those for whom this volume is intended they may be regarded as one.
Dwarf Silky Willow (Salix repens). It is a low bush from six to twelve inches high, the stem lying along the ground. Some of the branches straggle in the same fashion, but those which bear the flowers are more or less erect. The leaf-buds and the young leaves are silky, a condition that usually endures on the lower surface, and in some forms on the upper also. They are broadly or narrowly lance-shaped, varying in the different forms alluded to above; in size they range from a half to one and a half inches in length, and may have lance-shaped stipules, or none at all. The scales of the catkins are yellowish-green or purple, with dark tips. After they have shed their pollen the anthers turn black. One form or other of this species will be found in all parts of the British Islands where there are heaths or commons; in the Highlands it occurs as high as 2500 feet.
Another group of small Willows that form bushes (rarely a small tree) have been united under two species—the Dark-leaved Willow (Salix nigricans), and the Tea-leaved Willow (Salix phylicifolia). None of them occur south of Yorkshire, and the chief distinction between the two species (?) consists in the leaves of S. nigricans turning black when being dried for the herbarium, whilst those of S. phylicifolia do not.
The Osier (Salix viminalis). Many of the foregoing Willows, when cut down low and induced to send out long, slender shoots, are known as Osiers, but only two species are botanically regarded as Osiers—this and the Purple Osier (S. purpurea). The present species may remain as a shrub or grow into a small tree, thirty feet high, with long, straight branches, which are silky when young, but afterwards become polished. The leaves vary in length from four to ten inches, and are slenderly lance-shaped, tapering to a point in front, and narrowing into the foot-stalk behind. They have waved margins without teeth, and the upper surface netted with veins, the under surface silvery and silky; stipules narrow lance-shaped. The Osier may be seen in Osier-beds and wet places generally throughout the country as far north as Elgin and Argyll. There are several varieties and hybrids.
The Purple Osier (Salix purpurea). In all the other Willows mentioned the stamens, whatever their number, all have the filaments distinct from each other. In this species alone the filaments of the two stamens are more or less united. The Purple Osier gets its name from the red or purple bark which clothes the thin but tough twigs. It is a shrub, and grows from five to ten feet high. The leaves, which are rather thin in texture, are from three to six inches long, of slender-lance-shape, with toothed edges, smooth and glaucous on both sides, but especially beneath, somewhat hairy when young. They are almost opposite on the twigs, and when dried for the herbarium turn black. There are several varieties of this shrub, which were formerly honoured with specific rank.
There remains a group of several small species of very local occurrence, with which we can do little more here beyond naming them.
The Woolly Willow (Salix lanata) is a small shrub, two or three feet high, with twisted branches, woolly twigs, and hairy black buds. The broad egg-shaped or oblong leathery leaves are also woolly, and two or three inches long. There are half-heart-shaped stipules at the base of the very short leaf-stalk. It is an Alpine plant, and is found about the mountain rills of Perth, Forfar, Inverness, and Sutherland at elevations between 2000 and 2500 feet. Conspicuous in spring for its rich golden catkins. Sadler’s Willow (S. sadleri), of which only two or three specimens have been found (in Glen Callater, 2500 feet), is probably a form of this species.
The Lapland Willow (Salix lapponum) is of a similar proportion to the last-named, sometimes erect, sometimes trailing. Its leaves are more elliptic in shape, covered above with silky hairs and below with cottony filaments. In lanata the raised veins form a network pattern; in lapponum they are straight. The stipules at the base of the long foot-stalk are small or altogether wanting. Like the preceding species, it is restricted to Scotch Alpine rocks, at elevations between 2000 and 2700 feet.
The Whortle-leaved Willow (Salix myrsinites) is a small, wiry, creeping, or half-erect shrub, six inches to a foot high, with toothed, dark glossy leaves, an inch or less in length, whose net-veining shows on both sides. It is restricted to the Alpine parts of mid-Scotland, from 1000 to 2700 feet.
The Small Tree-Willow (Salix arbuscula) is a small shrub, whose stem creeps along the ground and roots as it goes, sending up more or less erect branches a foot or two high. The downy twigs are first yellow, then reddish-brown. The small leaves vary from egg-shaped to lance-shaped, and are shining above and glaucous beneath; toothed. In the Highlands of Aberdeen, Argyll, Dumfries, Forfar, and Perth, between 1000 and 2400 feet.
The Least Willow (Salix herbacea) is not so restricted in its range, for it is found in all parts of the United Kingdom where there are heights sufficiently Alpine (2000 to 4300 feet) for its tastes. It is only an inch or two high, and has consequently the distinction of being the smallest British shrub. It is not so herbaceous as it seems, or as its name implies, for its shrubby stem and branches creep along underground, sending up only short, scantly leaved twigs. The curled, roundish leaves do not exceed half an inch in length; they are net-veined, toothed, and shining. The catkins appear after the leaves.
The Net-leaved Willow (Salix reticulata) is another of the Scotch Alpines. It is similar in habit to the last-named, but larger, its buried branches sending up twigs a foot long. The roundish-oblong, leathery leaves are not toothed; they are smooth above and glaucous beneath, strongly net-veined on either side. The purplish or yellow catkins do not develop till after the leaves. It is restricted to the mountains of Aberdeen, Forfar, Inverness, Perth, and Sutherland.
The Weeping Willow (Salix babylonica), so conspicuous an ornament of riverside lawns, is an introduced species, whose slender branches hang downwards. It has large, lance-shaped, finely toothed leaves, smooth above and glaucous beneath. Further description of so well-known a tree is unnecessary. It attains a height of forty to fifty feet. The name babylonica was bestowed in the belief that its headquarters were on the banks of the Euphrates. It is now known to be a native of Japan, and other parts of Asia.
The name Willow is the Anglo-Saxon welig, indicating pliancy, willingness.
Featured image #LondonTrees Des McKenzie @McKenzie6593