|MadSci Network: Science History|
Assuming you are asking why fungi are classified as a separate group of organisms from plants, the answer has to do with reproduction, cell wall make-up, how they get nourishment and DNA. Fungi are actually more closely related to animals than plants. They reproduce by spores and have their cell walls made up of chitin. Plants have their cell walls made up of cellulose. Plants get their energy by photosynthesizing using their cholorplasts. In essence they make their own food. Fungi secrete enzymes into their substrate or food source and break the complex molecules down. They feed off of what they break down. It is much more detailed then what I've answered, but this should cover the basics.
Dr. Michelle Seidl
Try the links in the MadSci Library for more information on Science History.