A trichome is a small hair or growth from the epidermis of a plant, algae, lichen, and some protists. On cannabis plants, they appear in the form of crystallized glands that create sticky resin. While called hairs or crystals, these glands carry a vast amount of the cannabinoids found in the plant. When viewed under a microscope, trichomes have a mushroom-like appearance and are the main psychoactive component of the cannabis plant.