Maples belong to a large family (Sapindaceae) that includes Horse Chestnut, Soapberry and Lychee, writes our Chair, Mike Hildesley. The delicate and pretty Acer campestre or Field Maple, is the only native species to the UK. However, some of its more thuggish relations have naturalised so successfully that they can now be a threat to the balance in broad-leaf woodlands. We have four Acers on the Common.  I am also including the London Plane, which is the sole known living survivor within the family Platanaceae.

Sycamore (Acer pseudoplatanus) is naturalised in UK and grows vigorously in any damp fertile soil. The five-lobed leaves are quite large, leathery, and less defined than the more delicate Canadian maple leaf. Its dense canopy can shade out other trees and leaves rot slowly, carpeting out more delicate woodland flowers. Like all acers, its easy-to-recognise ‘helicopter’ V-shaped dual winged seeds (known as samaras) form clusters which can last into winter. Spiralling down, they can be carried some distance in strong winds and germinate easily.  Sycamore wood is almost white and easily carved.  It is used for kitchenware as it does not taint food and for carving decorative love spoons.  Sycamore is very popular with aphids, and anything underneath will be coated in ‘honeydew’. This in turn attracts ladybirds, hoverflies and small birds. It is host to many moths.  Sycamore is susceptible to fungal attack, especially sooty bark.  In older trees the bark begins to form plates which provide cracks and crevices for invertebrates. Rot can soften the wood, attracting woodpeckers whilst other cavities provide holes for roosting bats. Therefore it can be a useful tree from a conservation view, provided it does not take over. 

Norway Maple (A. platanoides) was introduced in 1680 and again, has naturalised so successfully, especially on sandy soils, that it can be invasive. On Barnes Common and at Leg o’ Mutton Reserve, saplings have to be controlled in their hundreds.

The leaves have the classic five distinct lobes but each has several points, making it easily identified from the sycamore. 

Sugar Maple (A. saccharum) is the famed maple which provides the Canadian national flag and produces maple syrup in North America. It is much more widely planted in the UK than many people realise and often mistaken for Norway Maple. The leaves are very similar, but the points are more rounded and less ‘whiskered’. Its leaves can be a dark copper when very young and are well-known for providing some of the best ‘Fall’ colour, turning first yellow then red, lingering through the shortening days of autumn. The bark gains a few broad fissures on the trunk as the tree ages. We have several examples at Vine Road Recreation Ground, at Scarth Road and at the corner of Woodlands Road.

Field Maple (A. campestre) is a true native, as mentioned and has only recently been introduced to the Common. Consequently, there are no mature trees. Across the UK it is often found in hedges, where some hedge layers are content to let it grow into trees rather than lay it back into the hedge.  The trademark maple leaves are much smaller than the non-natives. They turn a beautiful golden yellow in autumn before falling. Field Maple is known as a good pollution fighter which supports aphids, caterpillars and their predators.

London Plane: (Platanus x hispanica) is a hybrid of P. occidentalis (American/Western sycamore) and P. orientalis (Oriental/Eastern plane). It popularity in London is due to its tolerance to high levels of pollution, in part because it sheds its bark in platelets as it grows, although the trunk eventually forms a more permanent deeply-fissured bark in older trees. Whilst it may be good in pollution, it can be a cause of considerable suffering for some hay-fever sufferers.  Along with its distinctive bark, the trees are easily identified in winter by the hanging balls of seeds, looking like linked musical notation.

All our Plane trees on the Common are planted, but some are around 150 years old and still have many years to go.  The storm of 1987 proved too much for two of our trees that did blow over.  The trunks were sawn off. Interestingly, the roots were only partially pulled up and the trees have re-grown as if they had been coppiced. Each has half a dozen stems now well on their way to becoming substantial trunks after 43 years regrowth. (Locations: 1. near Rocks Lane, along the path parallel to Ranelagh Avenue; 2. near the SE corner of the Rocks Lane Tennis Courts). A London plane at Leg o’ Mutton is home to what is believed to be the largest Heronry along the Thames.

Acer leaf images: M Hildesley

This post is from a series of blogs Mike wrote during 2020 about the trees of the common. Other posts cover Cherries, Oak, Willows, Chestnut, Poplars and Thorn.