A family of leptosporangiate ferns, in which the sori are mixed, superficial on the lower surface of fronds, and usually rounded. They have a cosmopolitan distribution. In the wider sense, some 170 genera and several thousand species were included, but in the present-day classification (J. A. Crabbe and A. C. Jermy, Fern Gazette 11, 1975) the family is restricted to 56 genera.
Subjects: Plant Sciences and Forestry.