gonozooids heterosporous pistillate diploid dioicous sporophyte zygote gonads syncytia asexually conceptacles gamete meiosis sporophytes spermatia gametogenesis megaspores ovules sporangia spermatozoa parthenogenesis monoecious hermaphrodites mercapto Sundeep pseudohermaphroditism spermatogenesis zoospores Asexual ova unisexual unfertilized male hermaphrodite zygotes oogonia hermaphroditic interfoliar catkins