In the plant world, endophytes exist within plants to perform essential functions in the plant – stimulation of plant immunity, competitive inhibition (making sure there is no room left for an invader) and production of chemicals capable of killing other bacteria (antibiotics). This is a process called “symbiosis.” Symbiosis occurs when two organisms co-exist and one, or both, organisms benefit from the relationship. In plants, endophytes have evolved to be part of the growth mechanisms of the plant. They are found in the roots and in the leaves. What has this to do with Crohn’s disease?