Adiantoid

The Adiantoid clade is a group within the Pteridaceae, or maidenhair fern family, comprising about 6 to 12 genera and around 300 species. The most well-known genus in this clade is Adiantum, commonly called maidenhair ferns, which features about 250 species. These ferns are distinguished by their sporangia, which are located on the underside of small flaps of tissue along the edges of their leaflets. A notable example is the Northern maidenhair (A. pedatum), found in eastern North America and related species in western North America and East Asia. The former family Vittariaceae is also considered closely related and has been reassigned to the Adiantoid clade, containing about 140 species in genera like Vittaria and Antrophyum, often characterized by undivided, strap-shaped leaves.1