The Saccharomyces (yeasts) are non-mycelial ascomycetes that form no fruiting bodies. They are unicellular which may be globose, ellipsoid or shortly cylindrical in form, mostly these are saprophytes. The genus Puccinia includes about 3,000 species. These are mycelial fungus. Puccinia graminis causes black rust of wheat. It is hetroecious parasite. The mycelium of Rhizopus consists of numerous slender, freely branched filaments the hyphae. The mycelium is cottony while during vegetative phase however develop numerous black, pin head like structure during reproductive phase and therefore called black molds. The aerial mycelium of Mucor consists of copiously branched hyphae which ramiphy over the surface of the substratum and send down branches, which penetrate the substratum and absorb nourishment.