Flora of New Zealand Series

Terrestrial ferns with erect to long-creeping scaly rhizomes. Stipes scaly at base only, often dark brown and polished. Fronds entire or 1-4-(6)-pinnate; ultimate segments stalked, usually ovate, flabellate, oblong, or parallelogrammoid; margins incised, lobed, or crenate; veins usually free. Sori borne on elongate, orbicular, reniform, or crescent-shaped, strongly recurved modified marginal lobes (usually called indusia). Spores trilete.

c. 150 spp., mostly tropical but some in temperate regions. Native spp. 7, naturalised 2.

Adiantum has its centre of distribution in the New World tropics but extends also into N. and S. temperate regions. Most members of the genus can be readily identified as such by their shiny, dark brown stipes and rachises, their delicate fan-shaped or oblong pinnules, and the reflexed, often reniform, marginal lobes (indusia) which bear the sporangia. The different N.Z. spp. are distinguished by varying combinations of characters including the presence or absence of hairs on the rachis, underside of the pinnule and indusium, the attachment of the pinnule stalk at the centre or corner of the pinnule, and the shape of the indusium and pinnule (Fig. 6). Despite their appearance, many are hardy and some will withstand prolonged periods of drought. The genus is very popular in cultivation (as maidenhair ferns) and numerous cvs are available [Hoshizaki, B. J., Baileya 17 : 97-191 (1970); Goudey, C. J., Maidenhair Ferns in Cultivation (1985)].

Fig. 6. Ultimate lamina segments of Adiantum. A A. capillus-veneris; B A. raddianum; C A. aethiopicum; D-E A. diaphanum, D segment, E indusium; F-G A. hispidulum, F segment, G indusium; H A. viridescens; I A. fulvum; J A. formosum; K A. cunninghamii. © All rights reserved. [Image: 4X5K]