Cecidium

Galls (from Latin) or cecidium (from Greek): outgrowth, deformity on plants caused by insects, acarians, nematodes, fungi, viruses, bacteria or plants. The science that studies galls is called cecidology.

"We consider all manifestations of growth, whether positive or negative, and abnormal differentiations caused by animal or plant parasites to be gall. " (Meyer,1987 in Dauphin & Aniotsbehere, 1993.)