Mycology is a branch of biology which focuses on fungus lifeforms. Those who study mycology are known as mycologists. Affects of the psychoactive drugs found in certain mushrooms are studied by the field of psychochemistry.
Hikaru Sulu was an amateur mycologist. In 2269, he inspected a variety of toadstools on the surface of a cloaked planet, keeping one specimen in his pocket to study later. (TOS novel: Assignment: Eternity)