The native Black Poplar is now the least common of all our native trees. Yet until about 1850, it was widely planted because its timber was much sought after because of its special qualities. It was fire-resistant and used for floorboards around hearths. Its shock-absorbent qualities made it suitable for making wagons. Its pale colour lent itself to furniture-making, its hardness lent itself for weaponry - from arrows found on the Mary Rose to more recent rifle butts. But the native tree was replaced in popularity by hybrids and clones, which account for most of the Black Poplars we are likely to see now.
The British Black Poplar, sub-species betulifolia (populus nigra betulifolia) is a massive, fast-growing tree, reaching about 30 metres (100 feet). As it thrives in soil subject to flooding, it was planted alongside rivers and streams, by farm ponds and in wet meadows. A common field and parish boundary marker because of its distinctive shape - arching lower branches and leaning trunk - it can be seen in the background in many Constable paintings, including The Hay Wain. It lives for about 100 years before starting to decline, so any surviving specimens will be coming to the end of their lives.
In the early 1800s, male and female clones (populus canadensis) were developed. They were popularly used as screening alongside railways, so became known as 'Railway Poplars'. However, the female trees went out of fashion, as they are considered to be a nuisance because of the “fluff” shed from their catkins in May/June. Nowadays, only about five per cent of Black Poplars nationally are female. Both the male and female trees have catkins, but they do not last long in the male, whereas the windborne white seed-down that litters the ground around a female Black Poplar is a very distinctive feature of the species. The seeds, with their tufts of cottony hairs, are wind pollinated and will readily hybridise, although the fruit of the clones is usually sterile. From about 1850, the hybrids produced from the European Black Poplar and the North American Cottonwood (populus deltoides) became the preferred varieties, as they proved to be even faster growing and more easily propagated. The most familiar form is the tall, slim Lombardy, which is a male clone.
A number of different forms of the Black Poplar can be seen here in Dulwich and East Dulwich. They are in the Top Ten of trees that support wildlife species. The heart-shaped leaves of all the Black Poplars are very similar, but there are subtle differences, some of which can only be seen through a magnifying glass. (It’s worth carrying one in your pocket if you’re going on a tree trail). The male tree on the corner of St Aidan’s Road and Piermont Green has galls on its leaves, caused by aphids. Although the female trees are uncommon, a fine hybrid specimen can be seen on Peckham Rye, alongside the path from Barry Road to the main gates of Peckham Rye Park. This retains the beauty of its natural habit. It is in an open position and has been allowed to grow relatively unimpeded. Three types can be seen on the margin of Long Meadow on Gipsy Hill, although they have been too severely pruned to be attractive examples. There is a male hybrid as well as a male clone, a Lombardy Poplar. The photo shows the tree before the latest pruning, when it still retained one of its characteristic lower arched branches. The photo shows the tree before the latest pruning, when it still retained one of its characteristic lower arched branches. The other photo shows the bosses on the trunk, a characteristic absent in the cultivars. This could well be a rare native specimen, given that all that remains of these original trees are isolated specimens in wet meadows. If this is the case (and it would need a DNA test to prove it conclusively) and the tree is reaching the end of its lifespan, perhaps cuttings should be taken to provide successors locally of this historic landmark British tree.
Dulwich Society Trees Committee