In culture and in situ the parasitic red alga G. tuberifera Kylin undergoes a life history in which gametes, carpospores, tetraspores and uninucleate and binucleate bispores are produced. In culture, carpospores infect the host Agardhiella gaudichaudii (Montagne) Silva et Papenfuss resulting in the formulation of pustules which produce binucleate bispores and infrequently tetraspores. These spores infect additional host tissue resulting in the formation of gametes and carposporophytes. Infection by the uninucleate bispores results in the formation of binucleate bispores. The uninucleate bispores which are the dominant spore type in situ, provide an asexual alternative in this life history. In sexually reproducing individuals, the binucleate bispore carries 2 genotypes into a host. Culture studies reveal that both male and female gametophytes may develop within the tissues of a single host plant infected by a single binucleate bispore. The gametes are self-compatible. The capacity to establish both male and female gametophytes from a single spore infection may provide an important mechanism to insure the proximity of gametes in populations of this parasite.