As a comprehensive description is given in Tindale (1963), only a brief description, drawn up from New Zealand material, is given below. Rhizome thin, long-creeping, extensively branched and often matforming. Stipes 0.3-3.0 (-4.0) cm long, dark brown, sparsely hairy at base, elsewhere glabrous, always narrowly winged at apex, usually to half the length of the stipe and often almost to base. Main rachis with entire or toothed margin narrowing to base. Fronds 1-5 (-7) cm long, including the stipes, dark green, erect to decurved. Lamina 0.5-3.0 cm long, 0.5-2.0 cm broad, 2-pinnate-pinnatifid to 3-pinnatifid, ellipticoblong. All primary pinnae winged to rachis, alternate, lobed on both sides. Sori indusiate, marginal, on short lateral segments, usually solitary, mostly borne close to the main rachis on the acroscopic side of the secondary rachis. Involucre 1-1.3 mm long, 1.3-1.7 mm broad, obovate, two-valved, valves divided to base, wider than the ultimate segments, persistent, green, margin almost entire or erase or slightly denticulate. Receptacle included to slightly exserted at maturity.

This species, when growing in exposed places (Fig. 4 d, e), may resemble H. revolutum in habit and in possessing a solitary sorus, but the entire margin to the valves and the rachis winged throughout are constant differences. Typical H. peltatum (Fig. 4 a-c) is approached in habit by a form of H. revolutum (Fig. 3 a, b) which has the margins of its valves crenulate or only slightly denticulate. The branching of the pinnae is less bilateral than in many forms of H. revolutum, but the wing on the rachis does not extend past halfway. It is this form that grows with H. peltatum on the summit of Mt Te Aroha, South Auckland, but no intermediates have been seen there. No material that could be construed as intermediate between H. revolutum and H. peltatum has been seen. H. cupressiforme resembles H. peltatum more closely. Typical specimens of each should never be confused, but the elongate forms of H. cupressiforme with nearly entire indusial margins (H antarcticum), could be mistaken for the coarser forms of H. peltatum with only solitary sori. In these cases the most reliable distinctions are the shape of the indusia and the extent of the wing on the rachis (Figs. 2 c, 4 b, both basal pinnae). In H. peltatum the wing on the rachis is very narrow at the base and if it extends to the top of the stipe is only one cell thick and hardly visible. In H. cupressiforme the wing is distinctly wider at the base of the rachis and usually clearly visible at least halfway down the stipe.

This is the most easily distinguished of the New Zealand species, lacking a wing on the lower portion of the rachis. (In some very small specimens the rachis may be winged to its junction with the second to lowest pair of pinnae.) It is, however, most variable in appearance. Holloway (1923) commented that it is "extremely variable in its frond form but from the fact that different forms are not found intermixed and that they are characteristic of slightly different stations it would seem that they are the expression of small differences in the environment". A number of these forms are illustrated. A common form is shown in Fig. 3 c, d with typically bilateral branching of the pinnae, deeply toothed indusial valves, and a rachis winged less than halfway down. Fig. 3 e illustrates a form that is usually sterile and found in deep shade. The branching of the pinnae is unilateral and the rachis is winged nearly ¾ of the way to its base. The form shown in Fig. 3 f, g seems common in damp forests, particularly in the South Island. All these forms, with toothed indusia, wings confined to the upper part of the rachis, and solitary sori, are easily distinguished from H. peltatum. The lack of a wing on the stipe and all of the rachis is the best character distinguishing H. revolutum from H. cupressiforme (Fig. 2 a-e). The indusial margin, nearly entire to crenulate or denticulate in the latter and denticulate in the former, is often a useful additional character. The difference in the teeth of the lamina margin (often falcate in H. revolutum; mostly straight in H. cupressiforme (Tindale, 1963)) is not evident in New Zealand specimens.