In a scrubby field in St Leonards-on-Sea, East Sussex I found these cola nut galls (Andricus lignicola) yesterday growing on some young oak trees. The trees were most probably the hybrid (Quercus x rosacea) between pedunculate oak (Quercus robur) and sessile oak (Quercus petraea), not that I think this is of any significance so far as the galls are concerned.
They are caused by a small wasp and chemicals injected by the female at egg-laying time induce the galls to form, thus providing food for the larvae. The cola nut is a plant from tropical Africa and there is only a very superficial resemblance between it and these galls.
Although described as widespread and common, I have been unable to find any earlier Sussex records and, though seemingly not so frequent as the marble gall, I am sure it is overlooked rather than rare.
Sunday, January 14, 2007
Cola nut galls (Andricus lignicola)
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2 comments:
Mea culpa. Must get ALL records off to the Sussex Records Centre...... I've been interested in galls for a while. Cola Nut galls are, indeed, widespread in Sussex along with the more familiar Marble Gall (often mis-named Oak Apple). I found some small true Oak Apples recently - they definately have good and bad years. One record which I'm sure I had new for Sussex in 2004 was Andricus aries - the Ram's Horn Gall.
We have had Andricus aries here in Sedlescombe since 2001 and there are now many examples in a fairly recently planted oak wood on the Pestalozzi Estate.
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