Pteridium aquilinum is a perennial herb of Polypodiaceae. Underground rhizome is dark brown, long and horizontally extending, with a diameter of 0.6 ~ 0.8 cm, a length of 10 cm or more and a longest of 30 cm. Leaves grow from underground stems, which are three-pinnate compound leaves with a total length exceeding 100 cm and slightly triangular. The first 1 lobe is opposite, the second lobe is oblong-lanceolate, pinnately divided, the lobule is linear-oblong, the dorsal midvein is hairless or hairless, and the veinlets are pinnately branched. Leaf margin curled inward. When the petiole is tender, there are fine hairs, and after grassing, the stem is smooth and the hairs disappear. In early summer, the reproductive organs, that is, ascomycetes, are embedded in leaves, which are ochre-brown.