Stems creeping. Leaves to ca. 3(-30) m. Petioles borne 2-7 mm apart, 10-35 cm. Sterile pinnae on 1.5-3.5 cm stalks, triangular to lanceolate, 2-3-pinnate, 6-15 × 5.5-15 cm; ultimate segments lanceolate, lobed or divided proximally; lobes usually acute at tip and directed toward apex; segment apices long-attenuate to acute; segments not articulate to petiolules, not leaving wiry stalks when detached; blade tissue pubescent abaxially with short, curved hairs. Fertile pinnae on 1-2 cm stalks, lanceolate-triangular, 2-3-pinnate, 5-18 × 4-14 cm; ultimate segments ovate to lanceolate, fringed with fertile lobes, otherwise similiar to sterile segments.

Lygodium japonicum is native to eastern Asia. It is commonly naturalized or escaped from cultivation. It has been reported as weedy in southern Alabama and Florida where its dense canopy can eliminate underlying vegetation.