Adiantaceae

Abstract

The Adiantaceae, in the order of Pteridales, is a family of fern, consisting of only one genus, Adiantum Linn., with more than 200 species, widely distributed in tropical, subtropical, and temperate zones. Plants are terrestrial or epilithic, medium-sized or small. Rhizomes short and erect, or long and creeping, with siphonostele or primary dictyostele, covered with scales. Scales are lanceolate, brownish black, thick in texture, often entire. Fronds are monomorphic, fascicled or arranged two rows, scattered. Stipes are brown, chestnut or black, glossy, fine and rounded, and hard. Lamina is 1–3-pinnate, rarely solitary. Pinnules are ovate, flabellate, orbicular-flabellate, or dimidiate, margins serrate, lobed, or entire, usually deciduous when dried. Veins are slender, simple or dichotomously forked, free, and reaching to margins. Sori are borne on veins of recurved and membranous margins. False indusium is orbicular, reniform, lunate, rectangular, or oblong, free or continuous, upper margins forming deep sinus, retuse or truncate. Sporangia are globose, long-stalked, annuli erect. Spores are yellowish, tetrahedral, trilete, transparent, smooth. Only one species, Adiantum capillus-veneris Linn., is illustrated in the chapter.