Kind of. Tumors form when a cell (or group of cells) begins multiplying uncontrollably, usually in response to some DNA mutation. In plants, these growths are called galls, and they’re usually caused by bacterial or fungal infections. But one bacteria does cause plant DNA to mutate: Agrobacterium tumefaciens inserts a piece of its own DNA into a host plant and causes ugly, cauliflower-like galls. Thankfully, plants have rigid cell walls, so the diseased cells don’t spread. And if a gall takes out one organ, the plant can just grow another.