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A genus of ferns; several species are vermifugal.

The shield fern; a genus of polypodiaceous ferns.

In the U. S. Ph., the rhizome of Dryopteris filix mas Sebolt, or of Dryopteris marginalis Asa Gray. Aspidium contains a number of principles, upon which the activity is supposed to depend; these are found in the oleoresin of aspidium. They include aspidinin, flavospidic acid, albaspidin, filmarone, and flavospielinin, all of which are derived from phloroglucin and butyric acid.

(Bot.) Shield fern; a gen. of Ferns, of which common male-fern is the type ; formerly including ferns in which the dot-like sori were covered by a roundish cover, or, as it were, shield.