Retains water and minerals. Allows gas exchange. Protects the algae. The fungus produces unique organic compounds with several functions.
Fungal pigments shade the algae from intense sunlight.
Toxic fungal compounds prevent lichens from being eaten by consumers. Fungal acid secretion aids the uptake of minerals. Most of the lichen's mass is hyphal tissue which gives the lichen its shape and structure. Lichen reproduction occurs as a combined unit or as independent reproduction of the symbionts. Many lichen fungi reproduce sexually by forming ascocarps or rarely, basidiocarps.