28 Jan What Tree? Silver Birch
Silver Birch (Betula Pendula)
This month we are taking a closer look at the striking and easily recognisable Silver Birch. Native across most of Europe, it is commonly found throughout the UK and owes its name to the silvery-white peeling bark on its trunk.
Silver birch
Growing to heights of up to 30m, its trunk is slender, as are its resulting branches which bear long pendulous shoots. Its leaves are fresh green, changing to yellow in the autumn before it loses them. Its canopy is open and airy, allowing plenty of light to penetrate, which in turn enables a host of mosses, grasses and flowering plants to grow beneath and therefore providing habitat for a wide variety of insect and other wildlife.
This hardy tree is a pioneer species, one of the first to sprout on bare land or after a forest fire thanks to its light seeds which are easily blown on the wind, and it creates conditions suitable for other trees to become established. They are found as far north as Siberia, and in these northern regions they are steeped in legends and symbolism. In early Celtic mythology the birch symbolised renewal and purification – bundles of birch twigs were used to drive out the spirits of the old year. Indeed the word ‘betula’ comes from the Latin for ‘beat’ – switches were made from the young twigs and used as a means of punishment. These days bunches of young silver birch boughs are used to gently beat oneself whilst bathing in a Finnish sauna, and the country has adopted the silver birch as its national tree.
This species is an important timber producer. Its wood is pale in colour and can be used in a variety of ways including furniture making and plywood. In springtime the tree produces large amounts of sap which rise up through the trunk. This can be extracted by tapping the tree, and the resulting sticky liquid can be consumed raw or concentrated into a syrup by boiling off the water, or even fermented to produce an alcoholic beverage. Extracts from its leaves have been shown to cause a decrease in the inflammation caused by arthritis, and its buds have the potential to treat cancer because of anti-carcinogenic properties.
Appearance and identification
The silver birch is a medium-sized tree, typically reaching heights of around 15 to 25m. Its oval crown is loose and open. The spreading branches are golden brown at first, with pendulous thin twigs and small sticky buds, but as the tree grows it develops a white papery tissue on the surface which peels off in flakes. Mature trunks become coarse at the base with characteristic dark, diamond-shaped fissures.
Silver birch bark
It is a monoecious species, producing both male and female catkins. The former grow on the end of long shoots and hang in groups of two to four, with the latter developing in the spring on short shoots. The female catkins mature in midsummer when the male catkins release pollen, and the resulting small, winged seeds are spread widely by the wind when the catkins disintegrate.
The leaves of the silver birch are triangular with broad, untoothed wedge-shaped bases, slender pointed tips and coarsely double-toothed serrated edges.
Silver birch leaves
Propagation and control
The silver birch is a hardy tree, tolerant of a range of temperatures although it thrives in dry woodlands, downs and heaths. It is shallow rooting and prefers dry, acid soils. It shows good tolerance to pollution, making it a suitable choice for planting in industrial areas and exposed sites.
The branches often have a tangled mass of twigs known as a witch’s broom growing among them, which is caused by Taphrina betulina, a fungus which causes the leaves and catkins to curl.
Planted birch appears to be susceptible to birch dieback, which is caused by two fungal pathogens – Marssonina betulae and Anisogramma virgultorum. Naturally regenerated birch (grown from seed fallen from a tree) appears to be less prone to this disease.
Source and Reference Materials
Information detailed in this post has been obtained from the author’s own knowledge and photographic library where possible. Additional source of information and photographs include:
Van den Berk, B.V. (2004). Van den Berk on Trees. Van den Berk Nurseries.