Polypodiaceae J.Presl & C.Presl

Epiphytic, rupestral or terrestrial ferns. Rhizomes short- to long-creeping or erect, terete or occasionally dorsiventrally flattened, rarely with cavities, occasionally pruinose, scaly. Roots usually of one type, rarely of two types with one laterally inserted and clasping, the other ventrally inserted and attached to soil. Fronds monomorphic to trimorphic, articulated or not articulated to rhizome. Laminae usually undivided, lobed or 1-pinnate, rarely 2–3-pinnate. Veins free or reticulate; areoles usually with free included veinlets, rarely without; hydathodes present or absent. Sori round or elliptic or slightly elongate, superficial and not bulging on upper surface, or superficial and bulging due to thickening above the receptacle, or impressed into the lamina and bulging on upper surface, arranged in one or more rows either side of the costa, or sporangia scattered over the lamina surface; paraphyses often present; exindusiate. Sporangia with vertical annulus, usually 64 or rarely 8–32 spores per sporangium. Homosporous; spores monolete or rarely trilete, almost smooth to tuberculate or echinate, chlorophyllous or lacking chlorophyll.

A family of six subfamilies, 65 genera and about 1650 species (PPG 1 2016).

Although previous classifications treated Grammitidaceae and Polypodiaceae as separate families (Parris 1990; Hennipman et al. 1990), Smith et al. (2006) combined them into one monophyletic family based on phylogenetic analyses of chloroplast DNA sequences that showed the grammitids to be nested within Polypodiaceae (Schneider et al. 2004). Grammitids are now treated as the subfamily Grammitidoideae within Polypodiaceae (PPG 1 2016). In New Zealand they were retained as separate families by Allan (1961) and Brownsey & Smith-Dodsworth (2000).

The family name Polypodiaceae was attributed to Berchtold & Presl (1820) by Pichi Sermolli (1970). Berchtold & Presl treated Polypodiaceae at the rank of “řad” (order), but Pichi Sermolli argued that this should be regarded as equivalent to the modern family. However, a change to the rules of botanical nomenclature at Vienna (Art. 18.2, Note 1, Ex. 4) specifically states that “names published at the rank of order (“řad”) by Berchtold & Presl (1820) are not to be treated as having been published at the rank of family, since the term family (‘čeled’) was sometimes used to denote a rank below the rank of order”. The name Polypodiaceae was attributed to Presl & Presl by Smith et al. (2006).

Six subfamilies are recognised within Polypodiaceae (PPG 1 2016): Loxogrammoideae, Platycerioideae, Drynarioideae, Microsoroideae, Polypodioideae and Grammitidoideae. In New Zealand, Loxogramme is placed in Loxogrammoideae, Pyrrosia and the naturalised Platycerium in Platyceriodeae, Lecanopteris in Microsoroideae, and Notogrammitis in Grammitidoideae. Polypodioideae is represented only by introduced species of Niphidium, Phlebodium and Polypodium, and Drynarioideae does not occur outside cultivation in New Zealand.

Generic boundaries have been problematic worldwide in both Grammitidoideae and Microsoroideae. In New Zealand only one genus, Notogrammitis, is now recognised in Grammitidoideae (Perrie & Parris 2012), but resolving the taxonomy of Microsoroideae has been much more difficult. Historically in New Zealand two principal generic names have been used: Microsorum Link and Phymatosorus Pic.Serm. The former is often incorrectly spelled Microsorium, but that is an orthographic variant of the original name and should not be used (Bosman 1986). The latter is a replacement name for the earlier Phymatodes C.Presl, which is illegitimate (Pichi Sermolli 1973).

Copeland (1947) reluctantly included both groups within Microsorum even though he felt the types of these genera were “too unlike to be included in any natural genus”.  Nevertheless, he was unable to find any way to satisfactorily separate them. Bosman (1991) proposed a more restricted circumscription of Microsorum, distinguishing it from the other microsoroid genera, Colysis, Leptochilus, Neocheiropteris and Phymatosorus. In particular, Phymatosorus was distinguished from Microsorum by having more than five pairs of lamina lobes, anadromous rather than catadromous tertiary veins, a different arrangement of the sori on the veins, and sori sometimes sunk in the lamina. Following Bosman’s revision, the name Phymatosorus was quite widely adopted for the three species present in New Zealand. However, some of the diagnostic characters of Phymatosorus were questioned in a later treatment of the microsoroid ferns by Nooteboom (1997), who reverted to a broader interpretation of Microsorum.

Molecular evidence subsequently indicated that Microsorum was polyphyletic (Schneider et al. 2006). Moreover, M. punctatum and M. scolopendria, the types of Microsorum and Phymatosorus, respectively, occurred in the same core microsoroid clade, whereas the three New Zealand taxa belonged in a separate clade, along with species of Lecanopteris. Schneider et al. (2006) concluded that although the former group might be treated as Microsorum sens. str., the latter group had no satisfactory name available.

More detailed analysis by Testo et al. (2019) demonstrated three main clades within Microsoroideae. The first comprised Lepisorus and a number of smaller genera, the second included Microsorum sens. strict. and Leptochilus, and the third was made up of Lecanopteris and a number of smaller clades that included the New Zealand taxa. They recognised Lecanopteris, Bosmania, Dendroconche and Zealandia, the latter two genera encompassing the three New Zealand species.

Subsequent analysis by Chen et al. (2020) confirmed the presence of four clades in the Lecanopterid ferns, but they were less certain about the most appropriate taxonomic interpretation. While they considered Bosmania to be clearly distinct, they suggested three options for the remaining taxa: recognise Lecanopteris, Dendroconche and Zealandia as separate genera; recognise Zealandia alongside Lecanopteris plus Dendroconche; or extend Lecanopteris to include both Dendroconche and Zealandia. All three options offered monophyletic groupings, but on morphological grounds Chen et al. (2020) preferred the recognition of three separate genera.

The Microsoroideae and relatives are beset by morphological homoplasy.  After emphasising different morphological characters, Perrie et al. (2021) suggested recognition of an expanded Lecanopteris, including Denrdoconche and Zealandia.  Among the benefits of this classification, particularly for general users, was that groups of species that had traditionally been placed in a single genus were not distributed across different genera; notably L. pustulata and L. scandens, which are widespread and common in New Zealand and eastern Australia.  An expanded Lecanopteris is accepted here to include the latter two species, and L. novae-zealandiae.

The family Polypodiaceae includes ferns that have entire, pinnately divided, or rarely dichotomously divided laminae, and round or elongated sori lacking indusia. Subfamily Grammitidoideae is the most species-rich clade comprising generally small species with erect or short-creeping rhizomes, hairy or glabrous fronds, free venation, and chlorophyllous spores. Species of the other subfamilies are often larger and more conspicuous, with long-creeping rhizomes, glabrous fronds, net veins, and spores that lack chlorophyll.