Abstract: The development of gametophytes of three species in three genera of Polypodiaceae were studied. They are Polypodium vir-ginianum L., Lepisorus ussuriensis (Regel et Maack) Ching and Pyrrosia petiolosa (Christ) Ching. The spores of all the three species are yellowish, monolete, and kidney-shaped in equatorial view and elliptical in polar view, and variously ornamented. In culture the spores germina-te within 10-15 days. The patterns of spore germination seem to be Tangential as described by Momose (1942). Generally, the germ filaments develop 2-8 cells long, straight or curved.The prothallial development is of the Drynaria type (Nayar 1971). The prothalli matured in 8-10 weeks after inoculum.They are hairy, and rhizoids are brownish (often with a red-dish tinge). The antheridia are globular. A short stalked cell under the antheridium is often observed, especially when yo-ung. The archegonia are of the type common in the high ferns. The adult prothalli of three species are varied, broad obo-vate, length longet than width (often 3×2mm. in size) in polypodium virginianum, broad obovate-rounded, length almost equal to width (often 2×2mm.) in Lepisorus ussuriensis and broad-rounded, width broader than length (often 2×3.2mm.)in Pyrrosia petiolosa. The more primitive prothalli are naked. The three species in the present work have prothalli hairy, and the papillate secretory, unicellular hairs are common, clab-shaped in P.virginianum, obovate triangular in L. ussuriensis and short clab-shaped in P. petiolosa. In addition, the hairs in P. petiolosaare considerable complex and varied. They develop into bran-ched, multicellular (2-12 cells), uniseriate and multiseriate filaments occuring on the surface in a straight or curved fas-hion. All the cells contain fully chloroplasts except its bran-ch, sometimes bear 1-2 rhizoids. This leads to consider that these varied hairs are of adaptive value. With the evolutiona-ry development of the ferns, the hairs of prothalli in P.petiolosa might have been developing.