North temperate region and tropical America.

Plants creeping on wet ground. Roots emerging immediately on underside of stems. Horizontal stems on substrate surface, supine or arching. Upright shoots forming very leafy peduncles scattered along horizontal stems, 2-9 mm diam., unbranched. Gemmiferous branchlets and gemmae absent. Strobili solitary, fully differentiated from peduncle or peduncle not differentiated, tip blunt to ± acute; peduncle leafy, leaves not in distinct ranks, not imbricate, usually monomorphic, linear-lanceolate, margins commonly with a few teeth; sporophylls generally longer than peduncle leaves. Sporangia nearly globose. Spores rugulate, sides at equator convex, angles acute. Gametophytes photosynthetic, on substrate surface, pincushion-shaped; ring meristem absent. x = 78.
(Flora of North America)