Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
fauna, flora (nn.)
These are singular, not plural, meaning, respectively, “all the animals of a place or a period of time” and “all the plants of a place or period.” Fauna has two plurals faunas and faunae—and so does flora—floras and florae. The phrase flora and fauna nicely includes all the living things in a region or an environment and hence is a convenient cliché. See FOREIGN PLURALS.
