Plants terrestrial, main stem indeterminate, branched, subterranean (rhizome), or surface creeping or climbing and rooting at intervals, giving rise laterally to determinate, ascending to erect, very divided branchlet systems; branchlets with leaves spiral to almost whorled, or distinctly flattened and with leaves in rows. Leaves all similar or varying in size and shape. Strobili erect and terminal, sessile or stalked. Sporophylls broadly ovate to triangular; sporangia attached to sporophyll base or axillary; spore surface netted, striated or rough. Gametophyte subterranean, tuberous, saprophytic.
About 40 species, cosmopolitan, occurring in temperate and tropical regions; 3 of the 4 Australian species occur in Victoria.