Belongs within: Polypodiaceae.
Polypodium is a cosmopolitan genus of ferns, particularly diverse in the American tropics. Species of this genus possess a creeping rhizome from which fronds are borne. The circumscription of this genus has been subject to some dispute; it is now treated more narrowly than it has been in the past, and some authors would further subdivide it.
The common polypody Polypodium vulgare is a tetraploid species found in the western Palaearctic realm.
Polypodies: in the fernery of the senses
Published 22 February 2015
I’m not sure if I’ve ever had cause before to present my concept of the Evil Old Genus. The Evil Old Genus is one that has been used in the past to refer to a massively broader concept than it does currently, and so has been used to refer to many more species in the past than now. This makes dealing with the taxonomy of the genus a major headache, as one has to consider a whole host of now hidden or forgotten combinations. I can’t say what would be the most evil of the Evil Old Genera out there, but a definite leader has to be the fern genus Polypodium. When the name was used by Linnaeus way back in the mid-1700s, Polypodium referred to nearly the whole gamut of ferns. Over time, as botanists have come to appreciate that all ferns are not the same, Polypodium has been progressively cut down. Still, it seems that if you go back into the taxonomy of nearly any fern, you’ll come up against a ‘Polypodium‘ sooner or later.
At present, Polypodium refers to a group of ferns with creeping, often scaly stems. It is the appearance of these stems that gives them their genus name, meaning ‘many feet’, as well as the common vernacular name of polypody. The circumscription of the genus can still vary somewhat between authors: some would include about 250 species in the genus, but Smith et al. (2006) restricted Polypodium to only about 30 species found primarily in temperate regions of the Northern Hemisphere, and in Central America. Many of these belong to what is known as the Polypodium vulgare complex. Recognised in the past as a single species Polypodium vulgare, this complex is now recognised as including a number of species found across Eurasia and North America. Ten of these are diploids, but another seven are polyploids. The polyploid species are believed to have originated from hybridisations between the diploid taxa; for instance, the Eurasian Polypodium vulgare sensu stricto is a tetraploid derived from a hybridisation between the diploid species P. glycyrrhiza and P. sibiricum (Sigel et al. 2014). Sigel et al. (2014), investigating the relationships between its diploid species, estimated an early Miocene origin for the P. vulgare complex. A fossil species from the early Oligocene, P. radonii, may belong to the complex or may be closely related (Kvaček 2001).
Distinguishing species of the P. vulgare complex is no easy task, often requiring evaluation of subtle differences in leaf or stem form, or close examination of sporangium morphology. Another feature that has been used in distinguishing Polypodium species, however, is taste: the stems of some species in the complex have distinctive flavours. The Eurasian P. vulgare has been used to impart its bittersweet flavour to confectionary, while the vernacular name of the licorice fern P. glycyrrhiza of North America and eastern Asia is fairly self-explanatory (but like licorice, does it also give you a good run for your money?) The key to Polypodium species in the Flora of North America contains the somewhat unexpected advice that “the reader is cautioned to taste clean rhizomes from uncontaminated soils”. And honestly, who could argue with that?
Systematics of Polypodium
Characters (Hennipman et al. 1990): Epiphytic, epilithic, or terrestrial, small to large ferns; stem rather short to long-creeping, sometimes bearing a wax-like bloom, clothed with usually peltate or pseudopeltate, rarely basifixed, opaque, clathrate or centrally clathrate, entire to toothed scales, their margin usually bearing 1- or 2-celled, unbranched, glandular appendages. Leaves usually remote, articulate at base, monomorphic to dimorphic. Monomorphic and sterile leaves with short to long, scaly or glabrous petiole; lamina simple, pinnatifid, pinnatisect, or l-pinnate, rarely up to bipinnate + pinnatifid, most often deeply, pectinately pinnatifid to pinnate, truncate or narrowed at base, herbaceous to coriaceous, glabrous, pubescent, or variously scaly; veins free or anastomosing; venation simple to complex, usually with one row of areokes with one excurrent free vein, sometimes several rows of areoles with free, simple or forked veins that are usually excurrent or sometimes pointing to all sides. Fertile leaves conform to sterile ones or larger and/or narrower. Sori usually in one, sometimes more rows on either side of the primary or secondary veins, terminal or compital, usually rounded, rarely elongate or linear; sporangia long-stalked, annulus with about 12-20 indurated cells; receptacular hairs and/or scales of one form or another usually present. Spores hyaline to yellow, ellipsoidal, ends often obtuse; surface coarsely verrucate or low-verrucose, tuberculate, or papillate with dense globules, or with prominent wings; exospore of two layers, the outer verrucate or tuberculate; perispore thin, conforming to exospore, or in some species forming prominent folds; n=37, 74; 2n=74, 111, 148.
<==Polypodium
|--P. (ser. Dianeura) blechnoides [=Grammitis blechnoides; incl. P. contiguum]B78
|--P. ser. DictyophlebiaB78
| |--P. acrostichoides [=Niphobolus acrostichoides; incl. N. puberulus]B78
| |--P. attenuatum Brown 1810 [=Dictyopteris attenuata; incl. P. brownianum, P. brownii]B78
| |--P. aureumB78
| |--P. confluens [incl. P. glabrum]B78
| |--P. nigrescensB78
| |--P. phymatodes [=Pleopeltis phymatodes]B78
| |--P. rigidulum [incl. P. gaudichaudii]B78
| |--P. simplicissimumB78
| |--P. subauriculatum [=Goniophlebium subauriculatum]B78
| `--P. verrucosum [=Goniophlebium verrucosum]B78
`--P. (ser. Synneura) poecilophlebium [=Goniopteris poecilophlebia]B78
Polypodium incertae sedis:
P. alternifoliumBS-V28
P. amoenum Wallich ex Mett. 1857 (see below for synonymy)I88
P. angustatum [=Niphobolus angustatus]B78
P. angustifoliumL54
P. antillenseJ87
P. appalachianumSL05
P. astroplepisL54
P. atkinsonii Christensen 1906 (see below for synonymy)I88
P. brongniartii Bory de Saint-Vincent 1828BS-V28
P. californicumH93
P. calirhizaH93
P. cambricumPT98
P. cornigerumT-W89
P. cucullatumT-W89
P. decorumT-W89
P. delitescensL54
P. difforme [=Dictyopteris difformis]T-W89
P. dissimileJ87
P. eleagnifolium Bory de Saint-Vincent 1828BS-V28
P. filix-foeminaV97
P. filix-masV97
P. fuscatumT-W89
P. glaucescens [incl. P. trilobum]BS-V28
P. glycyrrhizaPS01
P. heracleumT-W89
P. hesperium [incl. P. vulgare var. columbianum]H93
P. heteromorphumL54
P. hirsutissimum Bory de Saint-Vincent 1828BS-V28
P. hirtellumT-W89
P. induensL54
P. khasyanumT-W89
P. lachnopus Wallich ex Hooker 1863 [=Goniophlebium lachnopus (Wallich) Bedd. 1883]I88
P. lanceola [=Pleopeltis lanceola]B78
P. lanceolatumL54
|--P. l. var. lanceolatumL54
`--P. l. var. trichophorumL54
P. laserpitiifoliumT-W89
P. lasiopusJ87
P. loriceumJ87
P. lyciaefolium Bory de Saint-Vincent 1828BS-V28
P. membranifoliumB78
P. microrhizoma Clarke ex Baker in Hooker & Baker 1874 [=Goniophlebium microrhizoma (Clarke) Bedd. 1876]I88
P. montigenumL54
P. neriifolium [incl. P. attenuatum Humb. & Bonpl. in Willdenow 1810 non Brown 1810]B78
P. obliquatumT-W89
P. papillosumT-W89
P. pectinatumJ87
P. perussumBS-V28
P. plumulaBS-V28
P. polypodioidesJ87
P. pteropusA78
P. scouleriH93
P. simplexP03
P. squamatumJ87
P. subamoenum Clarke 1880 [=Goniophlebium subamoenum (Clarke) Bedd. 1883]I88
P. subevenosumT-W89
P. tenuisectumT-W89
P. thysanolepisJ87
P. toenitis Bory de Saint-Vincent 1828BS-V28
P. triangulareT-W89
P. trifoliatumV97
P. triserialeL54
P. vacciniaefoliumBS-V28
P. virginianumMS98
P. viride Gilbert 1899 (n. d.)A61
P. vulgare Linnaeus 1753CD07
|--P. v. var. vulgareA61
`--P. v. var. auritum Gilbert 1899 (n. d.)A61
Nomina nuda: Polypodium isseli Squinabol 1889S89
Polypodium amoenum Wallich ex Mett. 1857 [=Goniophlebium amoenum (Wallich) Bedd. 1865; incl. P. amoenum f. pilosum Clarke 1880]I88
Polypodium atkinsonii Christensen 1906 [=P. hendersonii Atkins. apud Baker in Hooker 1874 non Lowe 1858, Goniophlebium hendersonii Bedd. 1876]I88
*Type species of generic name indicated
References
[A61] Allan, H. H. 1961. Flora of New Zealand vol. 1. Indigenous Tracheophyta: Psilopsida, Lycopsida, Filicopsida, Gymnospermae, Dicotyledones. R. E. Owen, Government Printer: Wellington (New Zealand).
[A78] Ananthakrishnan, T. N. 1978. Thrips galls and gall thrips. Zoological Survey of India, Technical Monograph 1: 1–69, 26 pls.
[B78] Bentham, G. 1878. Flora Australiensis: A description of the plants of the Australian Territory vol. 7. Roxburghiaceae to Filices. L. Reeve & Co.: London.
[BS-V28] Bory de Saint-Vincent, J. B. 1828. Voyage Autour du Monde, Exécuté par Ordre du Roi, Sur la Corvette de Sa Majesté, La Coquille, pendant les années 1822, 1823, 1824 et 1825. Botanique. Cryptogamie. Arthus Bertrand: Paris.
[CD07] Cantino, P. D., J. A. Doyle, S. W. Graham, W. S. Judd, R. G. Olmstead, D. E. Soltis, P. S. Soltis & M. J. Donoghue. 2007. Towards a phylogenetic nomenclature of Tracheophyta. Taxon 56 (3): E1–E44.
Hennipman, E., P. Veldhoen, K. U. Kramer & M. G. Price. 1990. Polypodiaceae. In: Kramer, K. U., & P. S. Green (eds) The Families and Genera of Vascular Plants vol. 1. Pteridophytes and Gymnosperms pp. 203–230. Springer.
[H93] Hickman, J. C. (ed.) 1993. The Jepson Manual: Higher Plants of California. University of California Press: Berkeley (California).
[I88] Iwatsuki, K. 1988. An enumeration of the pteridophytes of Nepal. In: Ohba, H., & S. B. Malla (eds) The Himalayan Plants vol. 1. The University Museum, University of Tokyo, Bulletin 31: 231–339.
[J87] Judd, W. S. 1987. Floristic study of Morne La Visite and Pic Macaya National Parks, Haiti. Bulletin of the Florida State Museum—Biological Sciences 32 (1): 1–136.
Kvaček, Z. 2001. A new fossil species of Polypodium (Polypodiaceae) from the Oligocene of northern Bohemia (Czech Republic). Feddes Repertorium 112 (3–4): 159–177.
[L54] Lötschert, W. 1954. Beitrag zur Pteridophyten-Flora von Mittel-Amerika. Senckenbergiana Biologica 35 (1-2): 109–119.
[MS98] Margulis, L., & K. V. Schwartz. 1998. Five Kingdoms: An Illustrated Guide to the Phyla of Life on Earth 3rd ed. W. H. Freeman and Company: New York.
[PT98] Panitsa, M., & D. Tzanoudakis. 1998. Contribution to the study of the Greek flora: flora and vegetation of the E Aegean islands Agathonisi and Pharmakonisi. Willdenowia 28: 95–116.
[P03] Paul, T. K. 2003. Botanical observations on the Purulia pumped storage hydropower project area, Bagmundi Hills, Purulia district, West Bengal. Bulletin of the Botanical Survey of India 45: 121–142.
[PS01] Pryer, K. M., A. R. Smith, J. S. Hunt & J. Y. Dubuisson. 2001. rbcL data reveal two monophyletic groups of filmy ferns (Filicopsida: Hymenophyllaceae). American Journal of Botany 88 (6): 1118–1130.
Sigel, E. M., M. D. Windham, C. H. Haufler & K. M. Pryer. 2014. Phylogeny, divergence time estimates, and phylogeography of the diploid species of the Polypodium vulgare complex (Polypodiaceae). Systematic Botany 39 (4): 1042–1055.
[SL05] Small, R. L., E. B. Lickey, J. Shaw & W. D. Hauk. 2005. Amplification of noncoding chloroplast DNA for phylogenetic studies in lycophytes and monilophytes with a comparative example of relative phylogenetic utility from Ophioglossaceae. Molecular Phylogenetics and Evolution 36: 509–522.
Smith, A. R., H.-P. Kreier, C. H. Haufler, T. A. Ranker & H. Schneider. 2006. Serpocaulon (Polypodiaceae), a new genus segregated from Polypodium. Taxon 55 (4): 919–930.
[S89] Squinabol, S. 1889. Res Ligusticae. VII.—Cenno preliminare sulla flora fossile di Santa Giustina. Annali del Museo Civico di Storia Naturale di Genova, Serie 2a, 7: 73–76.
[T-W89] Tenison-Woods, J. E. 1889. On the vegetation of Malaysia. Proceedings of the Linnean Society of New South Wales, series 2, 4 (1): 9–106, pls 1–9.
[V97] Ventenat, C. 1797. Extrait d’un mémoire sur les fougeres, de M. Smith. Bulletin des Sciences, par la Societé Philomathique de Paris 1 (9): 71–72.