# Polypodium

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.

## 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. As of February 2020, Checklist of Ferns and Lycophytes of the World accepted the following species and hybrids:
| Scientific name | Distribution |
| Polypodium abitaguae Hook. | Ecuador |
| Polypodium aequale Maxon | Mexico (Guerrero, Chiapas) |
| Polypodium alavae A.R.Sm. | Mexico to Honduras |
| Polypodium amorphum Suksd. – irregular polypody | SW. British Columbia to N. Oregon. |
| Polypodium appalachianum Haufler & Windham – Appalachian polypody or Appalachian rockcap fern | E. Canada to E. U.S.A |
| Polypodium arcanum Maxon | Mexico |
| Polypodium × aztecum Windham & Yatsk. (P. calirhiza × P. hesperium) | Arizona |
| Polypodium californicum Kaulf. – California polypody | California to N. Mexico, Guadalupe, Revillagigedos Islands. |
| Polypodium calirhiza S.A.Whitmore & A.R.Sm. | Oregon to Mexico. |
| Polypodium cambricum L. – southern polypody, limestone polypody, or Welsh polypody | NW. Europe to Medit. and Caucasus |
| Polypodium castaneum Maxon ex Tejero | Guatemala |
| Polypodium chiapense A.M.Evans & A.R.Sm. | Mexico (S. Veracruz, Oaxaca, Chiapas) |
| Polypodium chionolepis Sodiro | Ecuador |
| Polypodium chirripoense Lellinger | Costa Rica |
| Polypodium christensenii Maxon | Mexico (Chiapas) to Guatemala |
| Polypodium colpodes Kunze | Mexico to Venezuela |
| Polypodium conterminans Liebm. | Mexico to Honduras |
| Polypodium diplotrichum Mickel & Beitel | Mexico (Oaxaca, Chiapas) |
| Polypodium eatonii Baker | Central & S. Mexico |
| Polypodium echinolepis Fée | Mexico 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 Kuhn | SE. Brazil. |
| Polypodium fauriei Christ | Korea (Jeju-do), SW. Sakhalin, S. Kuril Islands to Japan. |
| Polypodium fissidens Maxon | Mexico (Oaxaca, Chiapas) to Honduras |
| Polypodium flagellare Christ | Costa 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 root | Kamchatka, Aleutian Islands to NW. U.S.A |
| Polypodium haitiense Urb. | W. Canada to N. Mexico |
| Polypodium hesperium Maxon – western polypody | W. Canada to N. Mexico |
| Polypodium hispidulum Bartlett | Mexico (Veracruz, Oaxaca, Chiapas) to Nicaragua |
| Polypodium × incognitum Cusick (P. appalachianum × P. virginianum) | E. Canada to NE. U.S.A |
| Polypodium interjectum Shivas | Madeira, Europe to Iran |
| Polypodium kamelinii Shmakov | S. Russian Far East |
| Polypodium kunzeanum C.Chr. | Costa Rica to W. Brazil and Peru. |
| Polypodium longipetiolatum Brade | Brazil (Minas Gerais to Paraná). |
| Polypodium macaronesicum Bobrov | Macaronesia, Spain (Cádiz). |
| Polypodium × mantoniae Rothm. (P. interjectum × P. vulgare) | Europe to Türkiye |
| Polypodium martensii Mett. | Mexico |
| Polypodium mollendense Maxon | Peru |
| Polypodium moricandii Mett. | Brazil (Bahia) |
| Polypodium moritzianum Link | NW. & N. Venezuela. |
| Polypodium otites L. | Cuba, Hispaniola, Jamaica. |
| Polypodium oxylepis C.Chr. | SE. Brazil |
| Polypodium pellucidum Kaulf. | Hawaiian Islands. |
| Polypodium pinnatissimum R.C.Moran | Costa Rica to Panama. |
| Polypodium plectolepidioides Rosenst. | Costa Rica |
| Polypodium plesiosorum Kunze | Mexico to NW. Colombia |
| Polypodium pleurosorum Kunze ex Mett. | Mexico to Central America. |
| Polypodium praetermissum Mickel & Tejero | N. & W. Mexico. |
| Polypodium puberulum Schltdl. & Cham. | Mexico to Honduras |
| Polypodium quitense Baker | Ecuador |
| Polypodium rhodopleuron Kunze | Mexico to Central America |
| Polypodium ryanii Kaulf. | Montserrat. |
| Polypodium saximontanum Windham | W. Central U.S.A. |
| Polypodium scouleri Hook. & Grev. – leathery polypody, Scouler's polypody, coast polypody, and leather-leaf fern | British Columbia to California. |
| Polypodium × shivasiae Rothm. (P. cambricum × P. interjectum. ) | Europe to NW. Türkiye. |
| Polypodium 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 trinidadense Jenman | Trinidad. |
| Polypodium ursipes Moritz ex C.Chr. | Central America, Venezuela (Aragua, Monagas). |
| Polypodium × vianei Shmakov (P. sibiricum × P. vulgare.) | SW. Siberia |
| Polypodium virginianum L. – rock polypody, rock cap fern, or common polypody | Subarctic America to U.S.A |
| Polypodium vulgare L. – common polypody | Madeira, 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