The condition of production of two different types of spores in the same species is known as the heterospory. The spores are differentiated into microspores and megaspores borne on the microsporangium and megasporangium. The microspores develop into male gametophyte whereas the megaspores give rise to female gametophyte. They are also known as the microgametophyte and megagametophyte. The heterospory is noticed in seven genera like Selaginella, Isoetes, Marsilea, Salvinia, Azolla, Renellidium and Pilularia.