Classification
 Subordinate Taxa
 Nomenclature
Scientific Name:
Polypodium L., Sp. Pl. 1082 (1753)
Type Taxon:
Etymology:
From the Greek polys (many), and podion (foot), a reference to the scars left when fronds fall off the rhizome, suggesting a centipede with many feet.
Vernacular Name(s):
polypody
 Description

Epiphytic, rupestral or terrestrial ferns.  Rhizomes short (not NZ) to long-creeping (NZ), scaly.  Rhizome scales non-clathrate, squarrose.  Fronds monomorphic to dimorphic, articulated to rhizome.  Laminae undivided (not NZ) to 1-pinnatisect (NZ), herbaceous to coriaceous, usually glabrous.  Veins reticulate (NZ) or free (not NZ); areoles with free included veinlets; hydathodes absent.  Sori round or slightly elongate, superficial, arranged in 1 (NZ) or 2 rows (not NZ) either side of midrib, not confluent with age, occurring throughout the lamina; paraphyses present (not NZ) or absent (NZ); exindusiate.  Spores monolete, bilaterally symmetrical, verrucate to tuberculate and sometimes papillate.

 Taxonomy

A poorly defined genus of about 200 species (Hennipman et al. 1990).

The treatment of Polypodium follows Brownsey in Webb et al. (1988) and Brownsey & Smith-Dodsworth (2000) in recognising a single naturalised species in New Zealand.  However, Gilbert (1899) described one new species, Polypodium viride, and one new variety, Polypodium vulgare var. auritum, from New Zealand.  These taxa were based on specimens collected by Dr C.H.F. Peters, astronomer-in-chief on the Transit of Venus expedition to New Zealand in 1874.  Peters was based in Queenstown and whilst waiting for an observatory to be built he collected ferns for Benjamin Gilbert back in America.  Some 25 years later, Gilbert described a new species and variety based on these collections, but they have been largely ignored ever since.  

Morton (1958) wrote a short paper on the two names, having succeeded in locating the Gilbert herbarium, previously thought to have been lost.  He illustrated the holotype of P. viride and suggested that it was the common polypody of the eastern USA – Polypodium vulgare var. virginianum (now treated as a distinct tetraploid species, P. virginianum L.).  Since no other species of Polypodium were then known from New Zealand, Morton concluded that Gilbert had described the species from American material inadvertently mixed up with Peters’ New Zealand collections.  He made no comment about the identity of the other taxon, P. vulgare var. auritum.

The fact that Polypodium is now known to be naturalised in New Zealand, albeit a long way from Queenstown, suggests the possibility that Peters’s collection may be the first known record.  It also raises the question of whether the Canterbury and Wellington populations are correctly as identified as P. vulgare rather than the closely related P. virginianum.  However, the latter species can be identified by its very distinctive paraphyses which are almost as large as the sporangia and characteristically gland-tipped (see Shivas 1961).  Morton (1958) noted that these paraphyses were present in the type specimen of P. viride, confirming the identity of that plant as P. virginianum.  However, plants from Canterbury and Wellington lack these paraphyses and are a different species.  It is very likely, therefore, that Morton was correct, and that P. viride is actually an American specimen of P. virginianum which became mixed up with Gilbert’s New Zealand specimens.  

Both of Gilbert’s names were excluded from the New Zealand flora by Brownsey & Perrie (2012).

 Distribution

Widely distributed in the Americas, and across Eurasia extending south to the Himalayas, Taiwan and southern Africa.  The majority of species occur in the American tropics. One species naturalised in New Zealand.

 Biostatus
Exotic
Number of species in New Zealand within Polypodium L.
CategoryNumber
Exotic: Fully Naturalised1
Total1
 Cytology

n = 37, 74; 2n = 74, 111, 148 (Hennipman et al. 1990).

 Bibliography
Brownsey, P.J.; Perrie, L.R. 2012: Taxonomic notes on the New Zealand flora: lectotypes and excluded taxa in the fern family Polypodiaceae. New Zealand Journal of Botany 50: 179–184.
Brownsey, P.J.; Perrie, L.R. 2015: Polypodiaceae (excluding Notogrammitis). In: Breitwieser, I; Heenan, P.B.; Wilton, A.D. (ed.) Flora of New Zealand — Ferns and Lycophytes. Fascicle 1. Manaaki Whenua Press, Lincoln.
Brownsey, P.J.; Smith-Dodsworth, J.C. 2000: New Zealand ferns and allied plants. Edition 2. David Bateman, Auckland.
Gilbert, B.D. 1899: Two new Polypodia from New Zealand. Bulletin of the Torrey Botanical Club 26: 316–317.
Hennipman, E.; Veldhoen, P.; Kramer, K.U. 1990: Polypodiaceae. In: Kramer, K.U.; Green, P.S. Pteridophytes and gymnosperms. Vol. 1. In: Kubitzki, K. (ed.) The Families and Genera of Vascular Plants. Springer-Verlag, Berlin.
Kramer, K.U.; Green, P.S. 1990: Pteridophytes and gymnosperms. Kubitzki, K. (ed.) The Families and Genera of Vascular Plants. Vol. 1. Springer-Verlag, Berlin.
Large, M.F.; Braggins, J.E. 1991: Spore atlas of New Zealand ferns and fern allies. SIR Publishing, Wellington.
Linnaeus, C. 1753: Species Plantarum. Impensis Laurentii Salvii, Stockholm.
Morton, C.V. 1958: The identity of Polypodium viride Gilbert. American Fern Journal 48: 75–77.
PPG 1 2016: A community-derived classification for extant lycophytes. Journal of Systematics and Evolution 54(6): 563–603.
Shivas, M.G. 1961: Contribution to the cytology and taxonomy of species of Polypodium in Europe and America. I. Cytology. Journal of the Linnean Society. Botany 58: 13–25.