Diploid gametophytes were produced via self-fertilization and apospory from a strain of haploid gametophytes which underwent apogamy in sterile culture. These diploid gametophytes of the fern, Pteridium, demonstrated quantitative differences from the haploid prothalli. The diameters of the rhizoids and antheridia were larger on the diploid prothalli. The diploid gametophytes grew slightly faster than the haploids. Under conditions which induced apogamy in the haploid prothalli, the diploids produced more apogamous sporophytes on a culture or on a weight basis than did the haploid prothalli.