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 (πολύ) "many" + podion (πόδιον) "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 10–80 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. 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 species and hybrids: Polypodium abitaguae Hook. Polypodium aequale Maxon Polypodium alavae A.R.Sm. Polypodium amorphum Suksd. Polypodium appalachianum Haufler & Windham Polypodium arcanum Maxon Polypodium × aztecum Windham & Yatsk. Polypodium californicum Kaulf. Polypodium calirhiza S.A.Whitmore & A.R.Sm. Polypodium cambricum L. Polypodium castaneum Maxon ex Tejero Polypodium chionolepis Sodiro Polypodium chirripoense Lellinger Polypodium christensenii Maxon Polypodium colpodes Kunze Polypodium conterminans Liebm.