In certain plants, the sexual phase (or an individual representing the phase) in the alternation of generations .
The alternate, nonsexual phase is the sporophyte . In the gametophyte phase, male and female organs (gametangia) develop and produce eggs and sperm (gametes), which unite in fertilization (syngamy). The fertilized egg (zygote) develops into the sporophyte, which produces numerous single-celled spores , which in turn develop directly into new gametes.