Oak 'Knopper' Gall


Oak galls start as small green acorns into which gall wasps lay their eggs. The wasp larvae grow inside the galls and the chemicals they secrete change the normal oak tree tissues from the smooth acorn shape into the gnarly bumpy forms of the oak knopper gall. When the largae crawl out, they leave a perfectly formed tunnel which also helps the oak galls to dry and become rock hard. Easily collected from the ground. You can find further information about oak galls on the website of The Royal Horticultural Society (UK)