Galls on Mint, Dog Rose and Germander Speedwell

Plant galls often attract attention and they are usually conspicuous at this time of year. They result from the invasion of a plant by another organism, commonly an insect (e.g. a midge of wasp), or a mite (a type of Arachnid), but also by viruses, bacteria, mycoplasma and fungi. They are very common and can often be identified quite easily, particularly if you can identify the host plant. The British Plant Gall Society produce some very useful keys and Plant Galls by Margaret Redfern , one of the more recent editions in the Collins New Naturalist series, is a very readable, scholarly piece of work.

The photographs (above and below) were taken on and near Baglan dunes this weekend:

The Robin’s Pincushion (caused by the wasp, Diplolepis rosae) and the Germander Speedwell Gall (caused by the midge, Jaapiella veronicae) are very common , invariably described and illustrated in the guide books and therefore easy to identify. However, I was unfamiliar with the Mint Gall and the guide books were of little help. I think it may be caused by Aceria megacera (a mite), but my identification is tentative and comments (and correction) will be very welcome.

The Robin’s Pincushion is also called Bedeguar, a very old Persian name for this iconic, natural phenomenon. At this time of year the ‘pincushions’ are often bright red in colour, so they are easy to pick out. It usually grows on Dog Rose (Rosa canina)