At maturity, megagametophytes contain hundreds of cells, including several archegonia that are aligned along the proximal spore surface at the wall dehiscence line. Unicellular rhizoids originate at the edges of the suture line and anchor the gametophyte to the substrate. Gametophytes of homosporous genera may be epiterrestrial or subterranean . The latter are achlorophyllose and in nature house an endophytic fungus that provides nourishment. In culture, spores of subterranean forms require extensive periods of darkness for germination and must be provided with sugars for nourishment.
Subterranean gametophytes are cylindrical and develop from an apical meristematic zone .
Gametangia in these forms are produced along the dorsal surface and are intermixed with simple hairs. A group of cover cells block the neck canal until the egg is mature, it which time these cells dissociate from the archegonium, freeing the neck for spermatozoids to enter. Antheridia are entirely embedded in the gametophyte tissue. In subterranean taxa, male sex organs may be massive , each producing several thousand tiny spermatozoids . Spermatozoids of Huperzia are smaller and more coiled than those of Lycopodium .