1. Adiantum L. (maidenhair fern)
Rhizomes short-creeping (long-creeping elsewhere). Leaves 1–2 times compound,
glabrous (to 4 times compound, hairy elsewhere). Pinnules obliquely
wedge-shaped to nearly rectangular, lobed apically. Veins easily seen,
branching dichotomously 1 to several times. Sori on the underside of the
recurved margins of the pinnules. Spores 64 per sporangium, 20–50 mm in diameter, yellow
to light brown. About 200 species, worldwide.
Several species of maidenhair ferns are cultivated either as indoor plants in
homes and greenhouses or as garden plants outdoors. The character of sporangia
borne on the undersurface of the reflexed margins of the pinnule lobes, rather
than on the main surface of the pinnule and covered by the reflexed margins,
makes this genus easily recognizable when plants are fertile.