Terrestrial or epiphytic ferns. Rhizome erect or creeping, with scales and/or hairs. Fertile and sterile fronds similar; stipe dark-coloured, often shining; lamina simple, 1–5-pinnate, pinnatifid or basally pedate; veins free or anastomosing, without free veinlets. Sori marginal, or apparently so, with or without indusia, often covered by reflexed margin of lamina, terminal on veins or spreading along them, and then without indusia; paraphyses present.
A cosmopolitan family containing a variable number of genera depending on the classification followed. Sometimes treated as monogeneric, but here including 2 other genera recorded from the Islands.
KEY TO GENERA
1 Sori discrete, kidney-shaped or subcircular
1: Sori merged, usually linear
2 Fronds 2- or 3-pinnate; pinnules less than 1 cm long
2: Fronds simply pinnate; pinnae 2–7 cm long
AdiantumL. Sp. Pl. 2: 1094(1753) Gen. Pl. 5th edn, 485 (1754); from the Greek adiantos (dry, unwetted), a name given by Greek authors to a plant with unwettable leaves, possibly A. capillus-veneris
Type: A. capillus-veneris L.
Terrestrial ferns. Rhizome short, creeping or erect, scaly at apex. Fronds: stipe erect, wiry, often lustrous; lamina 1–3 (–5)-pinnate or pedate, hairy or glabrous; rachis not grooved; pinnules sessile or stalked, often fan-shaped, usually marginally toothed; veins free and dichotomously branched. Sori apparently marginal, protected by reflexed flap from margin, discrete, circular or kidney-shaped.
A mainly pantropical genus of c. 200 species, especially from South America, but with a few temperate species; 2 species native to Norfolk Is. and 3 to Lord Howe Is.
Illustrations: D.L.Jones & S.C.Clemesha, Austral. Ferns & Fern Allies 2nd edn, 13, fig. 43 (1981); S.Firth et al., Ferns New Zealand 12, 13 (1986); P.J.Brownsey & J.C.Smith-Dodsworth, New Zealand Ferns & Allied Pl. 45, fig. 44, 45, t. 7B–C (1989).
Rhizome stoloniferous, 2 mm diam., covered with brown scales. Fronds: stipe 5–15 cm tall, c. 1 mm diam., shining, flexuous, smooth, blackish; lamina alternately 3-pinnate; pinnae 10–20 cm long, delicate, light green; petiolule 1–5 mm long, central to pinnule base; pinnules 3–11 per pinna, not arranged in a close series on either side of the pinna rachis, rounded obovate-cuneate, with upper margin serrate. Sori 2–6 per pinnule, in marginal notches; 'indusium' reniform.
Lord Howe Is. Growing in the Northern Hills. Also known from New Zealand (North Is.), Australia and South Africa.