Plant Gall Field Recorder Day

A plant gall is an abnormal growth of plant tissue caused by the invasion of another organism – for example, a wasp, fly, mite, fungus or even bacterium – within the plant tissue. Galls typically form on leaves, stems, roots, or flowers and come in an astonishing variety of shapes, sizes and colours. The structure itself forms due to the plant's response to irritation or chemical signals from the invading organism. Galls provide food and shelter for the invading organism inside and, while they may look unusual, are generally not harmful to the overall health of the plant.