The presence of two kinds of spores in the same species is known as heterospory. The two kinds of spores the microspores and the megaspores are found on the microsporangia and megasporangia respectively. In Selaginella germination of megaspores is insitu that is occurs within the mega sporangium and produces the female gametophyte. Even after fertilization the megasporangium remains attached to the sporophyte. The integument completely encloses the nucellus except at the micropyle. These integuments latter harden up and it protect the female gametophyte. The structure with the enclosed gametophyte and advanced embryo is known as the seed.
