The her1 mutation, which is one of many mutations that affect sexual differentiation in C-Fern, was induced by X-irradiation of spores. The effects of this mutation can be seen clearly in populations of gametophytes. Populations of wild type C-Fern gametophytes show two sexual types, males and hermaphrodites. In contrast, this maleless mutant does not contain male gametophytes in populations. This mutation renders gametophytes completely insensitive to the presence of the male-inducing pheromone, antheridiogen (ACe). On the other hand, development of hermaphrodite gametophytes occurs quite normally and appears no different from the wild type. It is also possible to see the effects of the mutation by using staggered sowings, over time, of spores on the same Petri dish; as is done in the Battle of the Sexes Kit (15-6752). For direct testing, it is possible to obtain a crude source of antheridiogen by growing multispore cultures of gametophytes for 2 – 3 weeks on C-Fern basic medium (CFBM) and then extracting the liquid from the medium. Extraction can be readily done by taking the older cultures, scraping most of the gametophyte material away and then freezing the remaining agar. After freezing, the agar can be thawed to effectively separate the solid portion from the liquid. The solution can then be filtered and used as the liquid to formulate new antheridiogen-supplemented C-Fern medium, which can be referred to as CFM+ACe. If spores of the wild type are sown on CFM+ACe, most of the gametophytes in the culture will be male. In contrast, if spores carrying the maleless her1 mutation are sown on such medium, all of the gametophytes will be hermaphrodites.

Banks, J. A., L. Hickok and M. A. Webb. 1993. The programming of sexual phenotype in the homosporous fern, Ceratopteris richardii. Int. J. Plant Sci. 154:522-534

Banks, J. A. 1997. Sex determination in the fern Ceratopteris. Trends in Plant Science 2:175 – 179.