Two important features are needed for any organism to be recognized as a plant: a) multicellularity; b) photoautotrophy. Particulary b) carries several functional and anatomic characteristics, such as the presence of chloroplasts. Fungi are not photoautotrophic, rather they need to eat other forms of life, mainly their carcasses. Even though they are multicellular and have a cell wall, they are very far from being considered as plants. Besides, their cell wall is pretty different from the plant's cell wall, while the former (fungic) has as main constituent quitin, the latter has their cell walls composed of cellulose.