Pteridaceae (Brake family)
Description: A specimen of this native perennial fern consists of a much-branched bipinnate leaf and its petiole. This compound leaf is 6-24" across and nearly as long; it is reniform (kidney-shaped) or fan-shaped in outline, and held more or less horizontal to the ground. The petiole is 6-18" tall; it is black or dark brown, wiry, and erect. The petiole divides into two major branches that widely diverge from each other. Along one side of each branch, there are several straight leafy stalks (pinnae) that are odd-pinnate. Each leafy stalk (rachis) is up to 12" long and 2" across; it has 4-24 pairs of leaflets along its length and a single terminal leaflet.
These leaflets are arranged alternately along the stalk on short petiolules; they are medium green. The non-terminal leaflets are up to ½" long and 1" across; they are plume-shaped. One side of the non-terminal leaflet is smooth and slightly curved, while the other side is shallowly cleft and crenate-dentate. The larger lobes of each leaflet have rounded or truncate tips. The terminal leaflets are up to ¾" long and ¾" across; they are fan-shaped. The lower two sides of the terminal leaflet are smooth and straight, while the upper side is shallowly cleft and crenate-dentate. The sporangia (spore-bearing structures) are located near the lobed tips of the leaflets. Each of these leaflet tips folds downward and partially covers its sporangia; these small sporangia are arranged together in a narrow band. The spores are produced and released during the summer or fall. The root system is fibrous and rhizomatous. Small colonies of plants are often produced from the long slender rhizomes.
Cultivation: The preference is light shade, moist to mesic conditions, and a loose fertile loam with an abundance of humus and decaying leaves. This fern likes high humidity and it should be located in a shaded area that is protected from the wind.
Range & Habitat: Maidenhair Fern is occasional to locally common throughout Illinois; it has been found in every county of the state. Habitats include rich deciduous woodlands, rocky wooded slopes, and shaded ravines where limestone or sandstone is close to the ground surface. Although it is fairly common, this fern is not normally found in degraded woodlands where the original ground flora has been largely destroyed.
Faunal Associations: Very little information is available about floral-faunal relationships for this fern. It has been reported that White-Tailed Deer don't browse on its fronds, which may be an indication of their toxicity.
Photographic Location: Along the wooded slope of a sandstone ravine at Shades State Park in west-central Indiana. The photographed plant is still immature.
Comments: This is one of the more distinctive and beautiful ferns in the state. Its closest relative is Adiantum capillus-veneris (Venus Hair Fern), which is located in areas south of Illinois. The central stalk (main rachis) of this latter species is branched on both sides; these side stalks are quite short and have only a few leaflets each. These fan-shaped leaflets are more narrow than those of the Maidenhair Fern. Sometimes Adiantum pedatum is referred to as the Northern Maidenhair Fern, while Adiantum capillus-veneris is referred to as the Southern Maidenhair Fern.