This Week: As we move through Spring on toward Longest Day, it is hard to imagine it is only a fortnight until the days begin to shorten. The rain and cloud cover in recent days has been a most welcome and needed visitor – although we are only just into June, everywhere trees are shedding leaves and grass is already brown. However, this sunniest of Springs has also given butterflies, damsel and dragonflies an early start, and everywhere are the sights and sounds of the insistent chirping of fledglings demanding to be fed, so do keep your eyes and ears open and let us know what you find!
The wooded areas on Barnes Common are classified as ‘secondary woodland’, meaning the area has not been continuously wooded throughout history. Our woodlands are primarily broadleaved with some conifers, most of which have been planted. Our most abundant conifer is yew, with the occasional pine, cypress, and cedar. There are no firs, larch, or spruce.
Yew (Taxus baccata) is a member of the relatively small Taxaceae family. One of only three conifer species native to the UK, it is dioicous (male and female reproductive systems on separate trees). The familiar berries are poisonous seeds surrounded by a deep succulent red cup called an aril. The foliage, especially when dried out, is also poisonous to most animals including humans and grazing livestock.
Due to the strength of its wood, yews can become ancient, long-lived trees. Even hollowed out boles can support heavy branches and live a thousand years or more. Yew is often associated with churchyards and there are many ideas and misconceptions around the reason for this. It may be that as Christianity arrived and sought to convert, it made sense to build one sacred structure on the site of an existing one. However, evidence for this is rare, with many churchyard trees more contemporaneous in age with the time the original Christian churches were built, and the sites consecrated. For centuries yew branches were carried on Palm Sunday and at funerals in England. Another possibility is that yew was vital to supply the yeomanry with England’s famous long bows and every village was required to grow yew trees on the orders of various kings. Because the tree is poisonous to livestock and one of the few enclosed spaces protected from grazing was the churchyard, this was a good place to grow them.
The ancient yew at Runnymede is thought to have been the gathering point for the signing of the Magna Carta (now located on the other side of the river at Ankerwyke, the Thames having changed its course). Surprisingly, until 1992, this historic tree remained neglected and overgrown. As you might expect, there is a rich Celtic mythology around Yew.
Yew wood has a long history of use: Neolithic longbows nearly 5000 years old have been found preserved in Somerset peat bogs. One of the world’s oldest surviving wooden artefacts is a yew spear head, found in 1911 at Clacton-on-Sea, Essex and estimated to be 450,000 years old. The wood has long been cherished for making furniture and household items such as bowls and drinking tankards, as well as the cogs of mills, axles and wheels, the bodies of musical instruments, and by the Vikings as nails in the making of their longboats.
On Barnes Common our oldest yews can be found in the Old Cemetery and are probably about 165 years old. The lovely old yew with a split trunk at St Mary’s Church, Barnes, may be 300 – 500 years old. Throughout the Common, our woodland areas are full of young yew saplings as a result of birds spreading the seeds. Like holly, yew thrives in the limited light of a woodland understory. It is also thought to generate toxins in the soil to discourage competition.
Medicinally, there are two chemotherapy drugs originally developed from yew trees: docetaxel (Taxotere) was first made from the needles of the European yew (T baccata) and paclitaxel (Taxol) was made from the bark of the Pacific yew (T brevifolia). Both drugs can now be made synthetically in the laboratory. Although no longer done, some UK firms used to collect yew tree clippings as part of the process of making the drugs. Our learning manager spent many hours working in a team clipping long lines of hedges in the early days of this research.
Scots Pine (Pinus sylvestris) is native to Scotland and based on pollen-dating evidence, introduced in England at various times. On the Common we have just two trees. Both are near the Mill Hill intersection and both are showing distinct signs of stress due to drought conditions in recent years. Scots pine has been a source of ‘deal’: timber much used in buildings, as well as for pit props, posts, and fencing (when suitably treated). Pines also produce the resins for true turpentine (and sealing birch-bark canoes). Scots pines live in symbiosis with various mycorrhizal fungi: young saplings are dependent on them and fail in sterilised commercial growing composts. There are several edible fungi associated with Scots pine, notably the Boletus pinophilus.
Bhutan Pine (P.wallichiana): This splendid pine (the only 5-needle pine you are likely to find in the UK) comes from the Himalayas, named after the Danish botanist Nathaniel Wallich who first introduced the seeds to England in 1827.
There is one example in the Old Cemetery, responsible for the large cones found there – but be prepared if you pick any of these up when they first fall: your hands will get covered in resin.
Cedar of Lebanon (Cedrus libani) Again, the only cedars on the Common are the result of plantings in the Old Cemetery. Introduced to the UK in 1640, a very cold winter in 1740 killed all known trees, so even the splendid specimens in park lands across the country date from 1760 or later.
Those in the cemetery will be at most 165 years old. Like many trees, they are susceptible to honey fungus (Armillaria spp)
Leyland Cypress (x Cupressocyparis leylandii) is a very fast-growing hybrid cross between two species that never would have met were it not for human manipulation: the Nootka (Xanthocyparis nootkatensis) and Monterey (Cupressus macrocarpa) cypresses. Nookta gives hardiness and Monterey gives speed of growth. ‘Leylandii’ has become a celebrated problem in recent decades as it is a far from ideal hedge plant, unless you really do want a forty foot high hedge or are prepared to keep up the routine maintenance a tree with this habit that is planted in the wrong place requires. I think the current number on the Common is now down to one. Enough said.
Next week: Holly
MH 8th June 2020