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Polypodium (family Polypodiaceae) A genus of ferns with pinnatifid or 1-pinnate fronds borne on creeping fleshy scaly rhizomes; the sori are naked and rounded. The sori vein ends on each side of the midrib of the pinnae, and leaf veins form loops with the free vein ends inside. There are some 75 species, with a cosmopolitan distribution.