Asplenium antiquum is a fern of the group known as bird's-nest ferns. In Japanese it is known by ō-tani-watari and tani-watari. Asplenium antiquum is an evergreen fern, 2–3 ft. (60–90 cm). It has bright green, arching blades with a pointed end and a strong midrib. Asplenium antiquum can readily be distinguished from the closely related Asplenium nidus by its fronds of uniform width.