Description
Herbaceous deciduous perennial. Dies back in winter. Underground long-creeping rhizome grows up to 15m long and is jointed and hairy. The fronds are 300-2000mm tall and produced singularly from the rhizome. Stipe is solid and glabrous, from half to two-thirds the length of the frond, with a brownish bulge at the base up to 100mm in diameter. The stipe is covered in soft hairs and shades to pale green above the base with numerous vascular bundles forming an O- or U-shape in cross-sectional view. Lamina are slightly arching, held vertically to near horizontal, up to 900mm wide at the base, roughly triangular, dull grey-green, papery to leathery and divided. Broadly triangular lamina segments are divided one or two more times. Hairs are present on the rachis, costae and on the lower lamina surface and there are nectaries on the underside at the bases of the pinnae and costae. Pinnae in 10 to 12 opposite or subopposite pairs with costae and rachis groved above with margins folding downwards. Veins are free (after branching from the midvein they do not unite with other veins) and forked until uniting at the margin. Continuous marginal linear sori, when present, are protected by false indusia of inrolled pinnulet margins. Sporangia are brown and mature at midsummer.
