The sporophyte produces haploid spores by meiosis that germinate to produce a multicellular gametophyte. The mature sporophyte produces haploid spores which grow into a gametophyte, thus completing the cycle. The haploid spores germinate and grow into a haploid gametophyte. The condition of having separate sporophyte and gametophyte plants is called alternation of generations. The condition of having separate sporophyte and gametophyte plants is called alternation of the generations. The relationship between the sporophyte and gametophyte varies among different groups of plants. In heteromorphic algae, the morphology and size are different in the gametophyte and sporophyte. The sporophyte remains small and dependent on the parent gametophyte for its entire brief life. The horn-shaped sporophyte grows from an archegonium embedded deep in the gametophyte. The endosperm is haploid, derived from the female gametophyte. Gametes are produced by the gametophyte, which is the haploid generation. In most flowering plants the female gametophyte within the ovule consists of only seven cells. In seed plants, a structure called ovule, which contains the female gametophyte. In gymnosperms, fertilization occurs within the archegonia produced by the female gametophyte. Each winged pollen grain is a four celled male gametophyte.