Plants with jointed stems, with distinct nodes. Leaves small, whorled, fused into sheaths; tips remaining free, toothlike. Sporangia borne on peltate sporophylls aggregated in cones 0.3–10 cm. Spores green (except white in hybrids), all 1 kind. Gametophytes green, terrestrial, unisexual; male gametophytes smaller than female.
Genus 1, species 15 (11 species in the flora).