The reproduction of most ferns involves an alternation of sexual and asexual generations. Few people can recognize the fern, however, in its sexual form, which appears as a tiny kidney-shaped plant referred to as the gametophyte or prothallium. The asexual form, known as a sporophyte, is representative of the fern as it is most commonly known. Sporophyte ferns are capable of reproducing both by vegetative cloning and by the production and dispersion of spores, which usually form on the underside of the leaves in clusters of spore cases called sporangia or sori. Depending on species, sori may appear on all or only a fraction of the plant’s leaves. When these structures dry out, they rupture, releasing the numerous spores they contain into the air where they may be carried by the wind to new locales for germination.