Epiphytic, lithophytic or terrestrial perennials. Stems erect, creeping or pendulous, sometimes elongated, dichotomously branched, bearing a few freshly dichotomously branched roots in a basal tuft, or irregularly along a creeping main stem. Leaves herbaceous to coriaceous, simple, spirally arranged or in irregular whorls with a single vein and without ligules. Sporophylls uniform, scale-like or leaf-like, sometimes similar to the foliage leaves; at other times arranged in cones (strobili). Sporangia borne in the axils of the sporophylls, solitary, 1-locular.