Aceria pseudoplatani causes the sycamore felt gall that is found on the leaves of sycamores (Acer pseudoplatanus) or Norway maple (Acer platanoides),[3] and is caused by an acarine gall-mite.
Appearance
The gall forms a bulge on the upper epidermis, where the pigment colour is usually light yellow to start with and brown later on in the year. The appearance on the lower epidermis is a concavity with cream- or white- coloured felt-like mat that later turns brown.[2][4] The bulge is due to the erinae, or hairs, being wider at their top. In purple-leaved varieties of the sycamore, the patches are pink.[3] The size of the felt-like patches is variable, and they may appear from late spring onwards.[5]
Distribution
The sycamore felt gall is quite common, is widespread throughout the United Kingdom[6] and is also recorded in Poland, Belgium, and Germany.[7]
Darlington, Arnold (1975). Plant Galls in Colour. Poole : Blandford Press. ISBN0-7137-0748-8.
Hancy, Rex (2000). The Study of Plant Galls in Norfolk. The Norfolk & Norwich Naturalists' Society.
Redfern, Margaret & Shirley, Peter (2002). British Plant Galls. Identification of Galls on Plants and Fungi. Shrewsbury : FSC Publications. ISBN1-85153-214-5.
