Plants terrestrial or epiphytic perennials (in the region). Robust or herbaceous; erect, creeping or scandent; branches alternate or dichotomous. Stems with exarch protoxylum, leaf gaps absent. Leaves microphylls, usually with a single unbranched midvein; simple, dimorphic or homomorphic, with or without a ligule, spiral to whorled or two-ranked. Roots with an endarch protoxylem. Sporangia borne in axils of modified leaves (sporophylls) and arranged in cone-like structures (strobili) at the tips of branches. Spores monomorphic (plants homosproric) or dimorphic (plants heterosporic).