The yeast plant and its allies are saprophytes and form no chlorophyll.
Most genera are saprophytes, but some - Chaetocladium, Piptocephalis - are parasites on other Mucorini, and one or two are associated casually with the rotting of tomatoes and other fruits, bulbs, &c., the fleshy parts of which are rapidly destroyed if once the hyphae gain entrance.
Fischer has proposed that the old division into saprophytes and parasites should be replaced by one which takes into account other peculiarities in the mode of nutrition of bacteria.
Some fungi, though able to live as saprophytes, occasionally enter the body of living plants, and are thus termed facultative parasites.
These they obtain usually in the form of carbohydrates from the dead remains of other organisms, or in this or other forms from the living cells of their hosts; in the former case they are termed saprophytes, in the latter parasites.