Many species of insects can co-opt a plant’s DNA to create a unique home and food for their larvae in the form of a gall. Swellings and disfigurations in plants caused by fungi, bacteria, and viruses are also kinds of galls.
The architecture of galls is extraordinarily variable and often very beautiful. Most galls are species-specific: a particular invading organism induces a particular host plant to produce a gall unique in size, shape, and color. Some plant species host many types of galls. Oaks, particularly those in the white oak lineage, host more gall insects than any other native tree or shrub in the western United States. Other organisms will take advantage of a gall, for example, by parasitizing the larvae. There are even galls in galls! The world of a single gall is a microcosm of the complex interrelationships in the natural world. Browse some of the galls found at Edgewood below.