Comparison of gametophyte growth, sex determination and reproduction in three fern species from the tropics

The gametophytes of Athyrium boryanurn, Thelypteris subpubescens and Pteridium aquilinum (vars. aquilinum, esculentum and wightianum) were grown as isolates, pairs and groups, and they were found to differ in their life histories: A. boryanum is a selfer which is sensitive to competition, while T. subpubescens is an ineffective selfer which is sensitive to competition, and P. aquilinurn is generally ineffective at sexual reproduction. A relationship between the level of gametophyte reproduction and the sporophyte viability was detected. The interactions between neighbours (competition or antheridiogen effects) appeared to influence gametophyte growth and reproductive success. In general, hermaphroditic gametophytes were considerably larger than males in all species, and those hermaphrodites which formed sporophytes were often smaller than other hermaphrodites.