Betula pendula Silver Birch

Silver Birch is a small, deciduous tree which is widespread and common in Britain. The silvery white bark and the drooping (pendulous) ends to the branches are very distinctive, paticularly in winter. It also has diamond-shaped patches (lenticels) on its usually warty and hairless twigs. It is a widespread species in West Glamorgan occuring in  woodland, hedgerows and scrub but less common than Downy Birch (B. pubescens) in Gower and perhaps less abundant on higher ground. A hybrid between Silver Birch and Downy Birch also occurs in West Glamorgan, but its distribution and status is less well understood. Birch trees often show a conspicuous twiggy growth called Witches Broom (see photo) which is a type of gall that is commonly attributed to infection by the fungus Taphrina betulina. However galls like this can be caused by other agents such as Phytoplasma, a type of bacterium that infects birch and other plants. It is transmitted by insects like leaf hoppers and carried in the phloem of the plant. Until recently it has been difficult to identify Phytoplasma in plants but it has become easier as a result of DNA sequencing technology. Birch trees may also have large burrs on them (see photo) which are usually the result of stress which might arise as a result of environmental factors, insect attack or microbial infections by viruses, bacteria or fungi.

Native