a family of plants of the class Filicales. They are perennials with creeping or sometimes ascending rhizomes that are covered with scales. The leaves are pinnate, twice pinnate, lobed, or entire. There are approximately 65 genera, with up to 1,200 species. They are found predominantly in the tropics, where they often develop as epiphytes. Five species of Polypodiaceae are found in the USSR: one Far Eastern species of the genus Pyrrosia and four species of the genus Polypodium. The wall fern (Polypodium vulgare) grows in the European USSR, the Caucasus, Middle Asia, and Western Siberia; its rhizome is sweet. Many tropical Polypodiaceae (Drynaria, Platycerium) are cultivated in greenhouses and as house plants.