Willows are the graceful guardians of our waterways, their leaves now mature and perfect for identification. But did you know this is one of the most complex and promiscuous plant families? With eighteen native species and over a hundred hybrids in Britain, telling them apart is a delightful challenge. From the broad-leaved ‘pussy’ willows to the slender leaves of the Cricket-bat willow, each has its own story. Discover the romantic and surprisingly dramatic history of the Weeping Willow, from its biblical misnomer to its connection with Napoleon. Uncover the secrets of these versatile trees, whose branches have been used for everything from baskets to cricket bats.
Return on August 26th for the full article!
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Willows
Willow leaves are now fully mature which means this is the best time since they were in catkin to hazard a field identification. In the spring they are notoriously misleading, often differing in shape and not developing characters such as teeth or inrolled edges until they are older. There are eighteen native species of willow in Britain and over one hundred different hybrids. Even in London perhaps half of these species can be found and quite a collection of their hybrids. Being notoriously promiscuous, not only are there hybrids but also backcrosses, variants, selections and sometimes even a perfect graduated sequence of intermediates between two parents. Gardeners have even managed to create hybrids involving thirteen different parents.
When examining willow leaves it is vital to note their overall shape, colour, whether they are hairy or not and the colour of any twigs they are growing on. Our London willows fall into two groups, those with round leaves and those with long ones, some of which may be twelve times as long as they are broad. The most common of the round-leaved willows are the two ‘pussy’ willows of the spring, the goat and the grey willow. Both produce bright sulphur yellow catkins that help to announce the spring all over the capital. The leaf shape of the goat willow Salix caprea is better described as broadly elliptical rather than round, with a short point at the end bent over slightly. The leaves also have a shiny upper surface and are slightly grey underneath with prominent raised veins. The leaves of the grey willow S. cineria are similar but larger and with less of a point. They have a wavy edge, duller upper side and are much greyer underneath.
Two other round-leaves species are the eared willow and the creeping willow. Both are rare in our area and easy to recognise. The eared willow S. aurita, which likes boggy areas, has small ‘ears’ or leaves at the base of its leaf stalks. Otherwise its main leaves also have prominent veins and a wavy edge but in this case the edge is also finely toothed. The creeping willow S. repens on the other hand is generally recognised purely by its small size as it rarely grows above a metre. The eared willow may still possibly be found by the river at Twickenham and the creeping willow in Epping forest.
The most common representatives of the long-leaved willows in London are the crack, white and weeping willows. The first two and their relations are the large willows we see along the edges of most of our waterways. Weeping willows and their relations have cascading branches and almost seem obligatory planting beside park lakes. They are all troublesome to identify precisely but it is easy enough to hazard a guess at their parentage. In the case of the crack willow S. fragilis breaking a branch and hearing a definitive ‘crack’ is not the best character to look for. These are the large, common willows we see along river banks, usually with wide open crowns.
They have a familiar long toothed leaf, but the leaf tapers to a finer point than most other willows. The leaves are also usually dark green with shiny upper sides and very distinct midribs. The true white willow S. alba is less common than the crack but found in similar situations.
It can generally be separated by its more graceful upswept crown. Its leaves are more of a blue-green, a little smaller and have a silky quality. Underneath they are almost a silvery grey which gives the whole tree a much paler appearance than the crack willow. They both hybridise so freely and so it is often a mixture of these characters that we encounter. If the tree looks like a white willow but has more of a blue-green sheen, especially from a distance, it may well be a cricket bat willow S. alba caerulea. When viewed closely its leaves are an attractive blue-green above and just bluish below.
These trees are phenomenally fast-growing, sometimes reaching thirty metres in a mere fifty years. They are common around London and the south east but rare elsewhere. They are always grown from cuttings which can take as little as twelve years to reach ten metres in height with a one and a half metre girth. At this point the bole is then cut into bat-size pieces. It is then cut again into eight segments to make eight bats. They are then further cut so that the blades of each bat always lies along the radius of the original bole. This ensures that the impact of any cricket ball is always softened by the wood and there will be no splitting. The best bats are made from female trees so we see very few males.
Weeping willows are everybody’s favourite and again something of a nightmare to identify precisely. They are trees that seem to have a natural propensity to reach out over water and then let their branches cascade down just to its surface. The true wild weeping willow S. babylonica is a rare tree which comes from a small area of Western China. Its specific name refers to the willows mentioned in the bible which grew beside the waters of Babylon. It is here where jews wept in their captivity and hung their harps in the trees. It seems much more likely that poplars lined the banks of any Babylonian rivers rather than willows. The large impressive weeping trees we see in London are usually some hybrid between the true parent and either a white or crack willow or even both. Especially popular are the crosses involving the golden form of the white willow S. alba ‘Vitellina’ which gave rise to the weeping willows with the familiar golden branches. These trees have always been popular and in Victorian London many were thought to have originated from a single specimen on the island of St Helena. Napoleon is said to have loved this particular tree and wanted to be buried beneath it. It later got stripped by Victorian souvenir hunters.
The last of the common willows is the osier S. viminalis with its rowing-boat shaped leaves. It is not usually seen as a tree as it is so often coppiced to produce ‘withies’ or whips for basket making. Generally we notice these coppiced trees in rows along the edges of waterways. Its leaves are long, inrolled and slightly waved. They are also silvery beneath with prominent veins. It is usually the general shape of the leaf and the thick mop of gracefully wafting ‘wands’ that betray their identity. These leaves are the longest willow leaves we see in the wild. Exceptionally long leaves seen on garden willows generally points towards the hoary willow S. elaeagnes.
Another rarer garden willow with similarly long leaves is the purple osier S. purpurea. Now it can be recognised by its purple stems but these were more of a reddish brown earlier in the year. It has bluish green, glabrous leaves without a tapering point. A useful field character is that its wood is bright yellow beneath if a little bark is rubbed off. The violet willow S. daphnoides has more plum coloured twigs covered in a natural bloom. Like the last species, it is occasionally seen in the wild but rarely far from a garden.
Two other rare willows can be recognised by their smell. The bay willow S. pentandra can still be found on Wimbledon common. Its leaves, which were sticky earlier in the year, are now leathery. If crushed, they release a scent similar to bay laurel. The almond or French willow S. triandra can be recognised by chewing its twigs which release a smell of rosewater. Its leaves seem intermediate between the long and round willows and are sometimes described as almond-shaped. A good place to look for wild willows is the Colne Valley, although all of London’s rivers are bordered by them.
More unusual species can be found in Hyde park, Holland park and Syon park. In Royal Victoria gardens the very rare shining willow S. lucida can be found. There is no salicetum in London considering there are three hundred species worldwide, but a national collection does exist in Harpenden.
