Polypodium is a genus of ferns in the family Polypodiaceae, subfamily Polypodioideae, according to the Pteridophyte Phylogeny Group classification of 2016 (PPG I). The genus is widely distributed throughout the world, with the highest species diversity in the tropics. The name is derived from Ancient Greek poly ("many") + podion ("little foot"), on account of the foot-like appearance of the rhizome and its branches. They are commonly called polypodies or rockcap ferns, but for many species unique vernacular names exist.
They are terrestrial or epiphytic ferns, with a creeping, densely hairy or scaly rhizome bearing fronds at intervals along its length. The species differ in size and general appearance and in the character of the fronds, which are evergreen, persisting for 1–2 years, pinnate or pinnatifid (rarely simple entire), and from 10 to 80 cm or more long. The sori or groups of spore-cases (sporangia) are borne on the back of the frond; they are globose and naked, not covered with a membrane (indusium).
Polypodies have some use in herbalism, but are today most important in horticulture where several species, hybrids, and their cultivars like Polypodium 'Green Wave' are commonly used as ornamental plants for shady locations. Polypodium have a bitter-sweet taste and are among the rather few ferns that are used in cooking; in this case as a spice e.g. for nougat.
__TOC__ Species Several of the species form hybrids with other species in the genus; these may often be distinguished by being sterile, with very small "blind" sori. , Checklist of Ferns and Lycophytes of the World accepted the following forty-seven species and eight hybrids: Image Scientific name Distribution Polypodium abitaguae Hook. Ecuador Polypodium aequale Maxon Mexico (Guerrero, Chiapas) Polypodium alavae A.R.Sm.Mexico to HondurasPolypodium amorphum Suksd. – irregular polypodySW. British Columbia to N. Oregon.Polypodium appalachianum Haufler & Windham – Appalachian polypody or Appalachian rockcap fernE. Canada to E. U.S. Polypodium arcanum Maxon Mexico Polypodium × aztecum Windham & Yatsk. (P. calirhiza × P. hesperium)ArizonaPolypodium californicum Kaulf. – California polypodyCalifornia to N. Mexico, Guadalupe, Revillagigedos IslandsPolypodium calirhiza S.A.Whitmore & A.R.Sm.Oregon to MexicoPolypodium cambricum L. – southern polypody, limestone polypody, or Welsh polypody NW. Europe to Medit. and Caucasus Polypodium castaneum Maxon ex TejeroGuatemala Polypodium chionolepis SodiroEcuador Polypodium chirripoense LellingerCosta Rica Polypodium christensenii MaxonMexico (Chiapas) to Guatemala Polypodium colpodes KunzeMexico to Venezuela Polypodium conterminans Liebm.Mexico to Honduras Polypodium diplotrichum Mickel & BeitelMexico (Oaxaca, Chiapas) Polypodium eatonii Baker Central & S. Mexico Polypodium echinolepis FéeMexico to Colombia Polypodium × encumeadense (Neuroth, Jäger & Bennert) F.J.Rumsey, Carine & Robba (P. macaronesicum × P. vulgare.)Madeira Polypodium ensiforme Thunb.Cape Provinces Polypodium eperopeutes Mickel & Beitel Mexico (Veracruz, Oaxaca, Chiapas) Polypodium exsul Mett. ex KuhnSE. Brazil. Polypodium fauriei ChristKorea (Jeju-do), SW. Sakhalin, S. Kuril Islands to Japan. Polypodium fissidens MaxonMexico (Oaxaca, Chiapas) to Honduras Polypodium flagellare ChristCosta Rica to Panama, Guianas to Brazil (Pará) Polypodium × font-queri Rothm. (P. cambricum × P. vulgare)Europe Polypodium fraternum Schltdl. & Cham.Mexico to Colombia.Polypodium glycyrrhiza D.C.Eaton licorice fern, many-footed fern, and sweet rootKamchatka, Aleutian Islands to NW. U.S.Polypodium hesperium Maxon – western polypodyW. Canada to N. Mexico Polypodium hispidulum BartlettMexico (Veracruz, Oaxaca, Chiapas) to Nicaragua Polypodium × incognitum Cusick (P. appalachianum × P. virginianum)E. Canada to NE. U.S.Polypodium interjectum ShivasMadeira, Europe to Iran Polypodium iranicum MazoojiIran Polypodium kamelinii ShmakovS. Russian Far EastPolypodium macaronesicum BobrovMacaronesia, Spain (Cádiz).Polypodium × mantoniae Rothm. (P. interjectum × P. vulgare)Europe to Türkiye Polypodium martensii Mett.Mexico Polypodium moritzianum LinkNW. & N. Venezuela Polypodium oxylepis C.Chr. SE. BrazilPolypodium pellucidum Kaulf.Hawaiian Islands Polypodium plesiosorum KunzeMexico to NW. Colombia Polypodium praetermissum Mickel & TejeroN. & W. Mexico Polypodium puberulum Schltdl. & Cham.Mexico to HondurasPolypodium rhodopleuron KunzeMexico to Central America Polypodium ryanii Kaulf.Montserrat Polypodium saximontanum WindhamW. Central U.S.Polypodium scouleri Hook. & Grev. – leathery polypody, Scouler's polypody, coast polypody, and leather-leaf fernBritish Columbia to California Polypodium × shivasiae Rothm. (P. cambricum × P. interjectum. )Europe to NW. TürkiyePolypodium sibiricum Sipliv.Siberia to N. & Central Japan and N. China, Subarctic America to W. & Central Canada Polypodium subpetiolatum Hook.Mexico to Central America, Cuba Polypodium × vianei Shmakov (P. sibiricum × P. vulgare.)SW. SiberiaPolypodium virginianum L. – rock polypody, rock cap fern, or common polypodySubarctic America to U.S.Polypodium vulgare L. – common polypodyMadeira, Morocco, Temp. Eurasia, S. Africa, Kerguelen Islands A number of species formerly included in the genus have recently been transferred to other genera, including Campyloneurum, Cyathea, Microgramma, Nephrolepis, Pecluma, Phlebodium, Pleopeltis and Serpocaulon. Species placed elsewhere include: Polypodium argyrolepis = Serpocaulon lasiopus Polypodium mindense = Serpocaulon eleutherophlebium Polypodium mixtum = Pleopeltis murora Polypodium piligerum = Moranopteris achilleifolia Polypodium punctatum Thunb. ex Murray = Hypolepis punctata Polypodium quitense = Pecluma dulcis Polypodium rimbachii = Serpocaulon sessilifolium Polypodium scutulatum = Serpocaulon fraxinifolium
References
Haufler, Christopher H.; Windham, Michael D.; Lang, Frank A. & Whitmore, S.A. (1993): 2. Polypodium Linnaeus. In: Flora of North America North of Mexico, Vol. 2 (Pteridophytes and Gymnosperms): 315–323. Hyde, H.A.; Wade, A.E. & Harrison, S.G. (1978): Welsh Ferns. National Museum of Wales. Royal Botanic Garden Edinburgh (RBGE) (2007): Digital Flora Europaea: Polypodium species list. Retrieved 2007-NOV-26. United States Department of Agriculture (USDA) (2007a): Germplasm Resources Information Network - Polypodium. Retrieved 2007-NOV-26.
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