TG3106 : Oyster gall on oak

taken 7 months ago, near to Surlingham, Norfolk, Great Britain

This is 1 of 6 images, with title Oyster gall on oak in this square
Oyster gall on oak
Oyster gall on oak
The tiny gall > LinkExternal link is caused by the oyster gall wasp, Neuroterus anthracinus, and measures only 2-3mm across. This gall wasp produces both sexual and agamic generations and hence forms two distinct galls, the oyster gall and the April-bud gall. The oyster gall is found on the leaf underside, rarely above and it is attached to the midrib or a main vain of the leaf with flaps of tissue. The parthenogenetic females of the agamic generation hatch from the oyster galls and lay their eggs within the buds, resulting in the sexual generation which emerges from the April-bud gall.
Plant galls
Galls are abnormal growths, swellings, pustules or discolourations produced by a plant or other host under the influence of another organism, involving the enlargement and/or proliferation of host cells and the provision of both shelter and food or nutrients for the invading organism. Galls provide a home for the larvae or grubs of certain invertebrates, where they can feed and develop, and each type of gall-producer or causer is specific to a particular kind of plant. Galls come in many shapes including spheres, knobs, lumps, warts or blisters, each being characteristic of the causal organism, and can have a range of colours. Galls can be found on the stems, leaves, flowers, fruits, seeds and roots of plants. Although many varieties of plants can be affected, oaks and willows are particularly rich in galls. Oaks are said to be host to more than 500 different types of galls. Weather, plant susceptibility, and pest populations affect the occurrence of plant galls.

Certain galls are documented to have been used in the production of ink since at least the time of the Roman Empire, and iron gall ink was the main medium used for writing in the Western World from the Middle Ages to the early 20th century. In Chinese medicine, oak galls are used as a remedy called moshizi, which is used for treating dysentery, ulcers and hemorrhoids among other things. Native Americans used poultices of ground gall nuts on sores, cuts and burns. The high content of tannic acid also makes oak galls a good source for tanning and dyeing.

Galls cause little permanent injury and rarely kill the infested plant.

For more detailed information go to the British Plant Gall Society's website at LinkExternal link
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TG3106, 218 images   (more nearby )
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Date Taken
Saturday, 19 August, 2017   (more nearby)
Sunday, 20 August, 2017
Geographical Context
Wild Animals, Plants and Mushrooms 
Subject Location
OSGB36: geotagged! TG 3127 0673 [10m precision]
WGS84: 52:36.5447N 1:24.8605E
Camera Location
OSGB36: geotagged! TG 3128 0671
View Direction
North-northwest (about 337 degrees)
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