Pai'i'iho

dentata: toothed; referring to the lobed pinnae

Rhizome shortly creeping, c. 10 mm in diameter; rhizome scales c. 5 mm long, dark brown, thinly pilose, entire. Fronds closely spaced, arching, not proliferous, thinly herbaceous. Stipe up to 25 cm long, pale to greyish brown, minutely pubescent to subglabrous. Lamina up to 1.6 × 0.54 m, narrowly elliptic to lanceolate in outline, deeply 2-pinnatifid, apex tapering to a point with a deeply pinnatifid terminal segment, basal pinnae 1 or 2 pairs reduced. Pinnae narrowly lanceolate, ultimate lobes oblong, slightly falcate, apex rounded, basal acroscopic lobe enlarged and sometimes overlapping the rhachis; sparsely hairy on both surfaces, more so along the costa and costules; veins 1 pair meeting below the sinus and sometimes a single vein joining in the sinus. Rhachis thinly set with long hairs. Sori round, up to 20 per lobe; indusia small, hairy, up to 1 mm wide.

Widespread in tropical and subtropical Africa, also in Yemen, Seychelles and Comoro Is., Madagascar, southern Asia, Australia, New Zealand, and introduced into tropical America.

Christella dentata is a small fern with widespread distribution in Australia and islands in the south Pacific Ocean. There are many local common names. In New South Wales it grows north from the southern Illawarra region and is known as binung.

Found on the margins of rainforest, by streams or in more open forests with adequate moisture. Sori are circular in shape, with a hairy closed covering.

It was the first species of fern to become naturalised on the Hawaiian Islands, recorded initially in Oahu in 1887 and now found on all major islands there. There it interbreeds with the local species C. cyatheoides, with the resultant hybrid offspring sterile.

Christella dentata is an edible fern, and also a folk remedy for skin diseases. Pharmacological study found that water extract of the fern was as toxic as anticancer drug 5-fluorouracil against human chronic myelogenous leukemia cell line (K562).