These are a group of ferns found in tropical and warm temperate regions. They are characterized by having delicate, fan-shaped fronds, arising from a thin black midrib, with small green leaflets. Maidenhair fern belong to the genus Adiantum, and some species are popular as house plants. In North America there are three common species, the northern maidenhair fern (A. pedatum), the southern maidenhair fern (A. capillusveneris), and the western maidenhair fern (A. aleuticum). They can grow up to 3 ft (1 m) tall and are generally found in clumps.
The leaflets are covered in a thick waxy epidermis with strong water-repellent properties (the Greek translation of Adiantum means unmoistened). The maidenhair ferns have been used as ingredients of medicinal shampoo, and also as hair restorer. In the sixteenth century they were also used to relieve asthma, snake bites, coughs, and as a stimulant.
The southern maidenhair fern tends to be found on shady, moist slopes with calcium-rich soil in the Southeastern and Gulf states and the Rockies as far north as Utah and west to California. Northern maidenhair fern occurs most abundantly in Virginia, though scattered collections are known from other coastal areas, as well as from woodlands within North and South Carolina and Georgia, and as far north as Ontario. Western maidenhair is also known as five finger maidenhair, due to the appearance of the leaves at the ends of the stalks, and it is native to western North America. Species of maidenhair ferns can also be found in Europe, around the Mediterranean and in Japan.
The maidenhair tree or ginkgo (Ginkgo biloba) is said to be named after this group of ferns because of the similarity of leaf shape. However, the ginkgo is a conifer tree, and is not related to the maidenhair ferns.