A fern plant consists of a stem, bearing leaves and roots. The leaves (or some of them) bear dehiscent sporangia, each sporangium containing unicellular spores, which are in most cases wind-dispersed. A spore germinates to produce a small green plant called a prothallus. The prothallus bears sexual organs (archegonia and antheridia). After fertilization by an antherozoid, the female cell in an archegonium grows to form a new fern plant. The life cycle of a fern thus has two phases, asexual (the fern plant) and sexual (the prothallus). These phases are also called the sporophyte and the gametophyte. The sporophyte is much longer-lived, larger and more diversified than the gametophyte, and its characters are mainly used in taxonomy. The following Statement deals with the parts of the sporophyte in turn, with discussion of the kinds of modification of each which occur, and of special terminology. Finally, a note on the gametophyte will be given, including reference to the not infrequent condition in which the sexual process is omitted.