Comparative Gametophyte Morphology of Selected Species of the Family Polypodiaceae

Gametophyte morphology and growth habit of seven epiphytic species of six genera in the Polypodiaceae are described.In addition to the Drynaria-type of early development, depicted previously in most of this family and expressed in all species observed, the Ceratopteristype, Adiantum-type, and Aspidium-type also occurred in some of the species observed.All species observed were long-lived, clone-forming, and without gemmae.The long-lived, clone-forming habit increases the space and time occupied by gametophytes, and thus enhances the probability of interaction with other gametophytes and the probability of intergametophytic mating in epiphytic habitats.Gametophyte morphologies vary greatly beyond the standard heart shapes usually depicted in textbooks (Atkinson and Stokey, 1964; Nayar and Kaur, 1971; Atkinson, 1973).These variations include the ability to grow indeterminately and to branch, so that perennial gametophyte clones of considerable