Gametophyte Morphology of the Fern Genus Drynariopsis (Polypodiaceae)

Abstract

As the gametophyte morphology of various fern groups has become better known during the past several decades, it has become increasingly apparent that gametophytes provide dependable morphological criteria for taxonomic and phyletic studies. Bower (1923-28) and Holttum (1949) pointed out that the comparative morphology of fern gametophytes can be of significance in understanding different phyletic groups. Stokey (1951, 1960), Atkinson and Stokey (1964), and Nayar and Kaur (1968, 1969, 1971) discussed the role of fer gametophytes in taxonomic and phyletic studies. According to Nayar and Kaur (1968, 1969), the patterns of spore germination and gametophyte development characterize various taxonomic groups, and so provide dependable data for comparative morphology. Nayar (1954, 1961, 1965), Nayar and Kachroo (1953), and Bajpai (1964) studied gametophyte morphology of some drynarioid ferns. Until now, no detailed studies of the gametophytes of the monotypic genus Drynariopsis have been made, although Nayar (1965) reported that Drynariopsis gametophytes show Drynariatype development. This study of Drynariopsis heraclea gametophyte development was made to compare the gametophytes of this primitive genus with those of other drynarioid ferns. Spores were collected from the fernery of the Natural Science Research Center, University of the Philippines. Gametophytes were raised on sterilized Knop's nutrient agar medium in petri dishes (Nayar, 1962). The cultures were maintained at 24+ 2? C under 600 ft-c of light from four fluorescent lamps placed horizontally above the culture dishes. All observations on morphology and development of the gametophytes are based on these laboratory cultures. To study cellular structure, the gametophytes were mounted in an acetocarmine solution, which induced partial plasmolysis of the cells and so rendered the cell outlines clear. Drawings were made using a camera lucida.