• Instructor: Joseph Langlois
• Fee: $85 (plus HST) per person if you register by the early bird deadline of July 17, 2026. After July 17 the fee is $95 plus HST.

Ever heard of a plant gall? Even if you haven't, you've likely seen one before! Galls are among the most overlooked signs of biodiversity around us, appearing as strange lumps, bumps, and growths on plants. They come in an incredible variety of shapes, sizes, colours, and forms, and can be found in nearly every terrestrial habitat. While they may look like a natural part of the plant, galls are actually created by other organisms—most often insects—that manipulate plant tissues to form these remarkable structures.

But what purpose do they serve? How are they formed? What groups of organisms are responsible for creating them? Do they harm the plant? How can we identify them? These questions and more will be explored during this workshop.

With the incredible plant diversity found throughout The Arboretum, we have the opportunity to discover a wide variety of gall-inducing species through the fascinating structures they create. The workshop will include an indoor presentation covering gall biology, diversity, and ecology, followed by a guided walk to search for and identify galls in the field.

View a complete list of Workshops [1]or Register for a Workshop [2].