I have always been fascinated by these strange yet sometimes most beautiful growths. Plant galls are something of an oddity when some folk first encounter them, others don’t even know they exist. Plant galls come in all shapes and sizes, and are formed by another organism using the plant as a host, using it for shelter and for food.
They are caused by insects or mites, fungi or bacteria, and cause a biological reaction within the plant which causes these odd lumps and bumps to form of their tissues. They affect both herbaceous and wood plants, and there are at least over 1,000 species in Britain alone.
It is most unlikely you would see the mite or insect which causes the majority of these galls for they are very small, some even microscopic, but the species can be identified by the galls they produce.The study of plant galls is called cecidology.