Once again the common culture of France and England shows itself through the identical names for this curious excrescence which grows upon the wild rose. And again if one searches for the original meaning, it emphasises the cradle of ancient medicine in the Arab world. The meaning is probably wind+rose from the Persian and Arabic languages, implying that the queer growth is carried on the wind. The medical connection is that the dried growths were used in an infusion to cure diarrhoea and several other complaints such as intestinal worms. The photo reminds me of the behavioural experiments with the bird, the Robin Redbreast (le rouge-gorge), where a male will attack a bunch of red feathers tied to a branch. This gall is not unlike a bunch of feathers and such a Quixotic conflict might well occur in nature. The name 'Robin's pincushion' might relate to the bird Robin but is usually said to refer to Robin Goodfellow or Puck, from the ancient belief in this woodland sprite and his wilful tricks. It is not surprising that such a mysterious growth evokes these superstitious connections. The true origin is in the infection of a young bud by the egg of a small gall-wasp. This produces hormones, chemicals which cause the bud to develop many dwarfed and disorganised thin stems creating the mossy reddish growth. The same chemicals create at the heart of the mass several woody cells in each one of which a maggot lives absorbing nutriment from the tissues of the rose. By winter time the colour has gone and the gall is but a brown and brittle mass. The maggots, now converted to pupae remain in the cells. These will emerge the following April as minute black wasps. Ninety nine percent of adults are females and these continue the generations without any sexual encounter. However the bedeguar is notorious in ecology for the numerous yet smaller wasps which parasitise the original parasite. At least six other species of minute wasps attack either the first perpetrator of the gall, or in sequence, the wasps which parasitise the first in line. It is a true realisation of the saying "Fleas have lesser fleas upon their backs to bite 'em-- and they have smaller fleas - and so ad infinitum!"
I have never seen this gall on a cultivated rose, and I wonder how many species of wild rose get the disease? In this instance it is the sweet brier rose.
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