If it can do neither it must either content itself with a saprophytic existence or fail, so far as that particular host-plant is concerned.

The Perisporiaceae are saprophytic forms, the two chief genera being Aspergillus and Penicillium.

Bilaterally symmetrical, often creeping, pharynx highly developed, with a firm rod-like skeleton, sometimes protrusible; nutrition saprophytic and holozoic.