Description from Flora of China
Plants small to medium-sized, often epiphytic. Rhizomes long creeping, mostly dichotomously branched. Stems erect to somewhat pendulous, glabrous, repeatedly dichotomously branched; branches green, ridged or complanate. Leaves reduced, veinless, sessile, dimorphic; trophophylls scalelike, subulate-triangular; sporophylls deeply bifid. Sporangia 3-lobed, attached at bases of sporophylls. Spores oblong in polar view, reniform in equatorial view, monolete, foveolate.
Psilotum complanatum O. Swartz, which differs from P. nudum in its flattened stems 1.5-3 mm wide, has been reported from Malaysia and Oceania (among other regions). It eventually may be discovered in S China.
Two species: widespread in tropical and warm-temperate regions; one species in China.