Acrostichum dichotomum Linnaeus, Sp. Pl. 2: 1068. 1753; Schizaea biroi V. A. Richter; S. kikuzatonis M. Ogata.

Rhizome shortly creeping, bearing 1 or 2(-5) erect fronds; hairs on rhizome and stipe bases multicellular, brown to pale brown, ca. 3 mm. Fronds fan-shaped; undivided portion 20-50 cm; stipe not winged and barely distinct from winged portion or lamina, sparsely hairy; upper portion 2-8 times dichotomously divided, lamina-like with lobes 1-1.5 mm wide; whole lamina 10-30 × 7-20 cm, somewhat variable in size. Sporangium-bearing lobes 5-10 pairs arranged pinnately at apex of ultimate frond lobes, lowest ones largest, 3-4 mm; sporangia in 2 regular rows on lobes, with long brown paraphyses.

Plants from Taiwan and the Ryukyu Islands have been treated as a distinct species, but it is difficult to distinguish a local form of this widely distributed, variable species.

Dry forest floors in lowlands. Hainan, S Taiwan [India, S Japan, Myanmar, Thailand; widely distributed in palaeotropics, Australia, and Pacific islands].