CalagualaPolypodium leucotomos

Did you know?

• Aureum is Latin for "golden", a nod to the golden scales that cover the fern's creeping rhizome; one of its English names is gold-foot fern^{[4, 6]}.

• In Florida the golden polypody often grows in the "boots", the old leaf bases left on the trunks of cabbage palms; gardeners also call it cabbage palm fern^{[6, 10]}.

• It is native to the United States, growing wild as far north as Florida, Georgia and Alabama^{[1, 10]}.

• Gardeners grow it as a houseplant, often in hanging baskets that show off its fuzzy rhizomes, under names such as hare's-foot fern and rabbit's-foot fern^{[2, 4, 6]}.

• A blue-green garden form is sold as the blue star fern^{[4, 6]}.

• Samambaia, the everyday Portuguese word for a fern, comes from Tupi, an Indigenous language of Brazil^{[11, 12]}.

Origins and history

Calaguala ferns are epiphytes: they usually grow on tree trunks and palms rather than in soil, though they can also root among rocks or in humus on the ground^{[1, 6, 7, 10]}. The golden polypody creeps along its host on a rhizome about 2 centimeters (three-quarters of an inch) thick, covered in golden scales, and sends up large fronds up to about 4 feet (120 centimeters) long^{[6, 7]}. Like all ferns, it has no flowers or seeds and reproduces by spores, carried in round clusters on the undersides of its fronds^{[10, 13]}. In Peru it grows on tree trunks and mossy rocks in the mountains, at about 900 to 2,600 meters^[7].

Linnaeus named the golden polypody Polypodium aureum in 1753, in his Species Plantarum^{[1, 5]}. The genus name Polypodium, like the English "polypody", comes from the Greek for "many feet"^[14]. Half a century later, in 1804, it was described again as Polypodium leucotomos, the name that most skin research still uses^{[1, 5, 8, 9]}. In 1841 both calaguala ferns were moved into the genus Phlebodium, where botanists place them today^{[1, 5]}.

Calaguala is the name used in Spanish-speaking Latin America^{[2, 3]}, while in Brazilian Portuguese any fern, calaguala included, is a samambaia^{[11, 12]}. Modern interest centers on the leaf. A standardized water extract of golden polypody leaves has been sold in Europe since 2000 and is now available in more than 26 countries, including the United States, where it is sold as a dietary supplement^[8].

Traditional uses

Calaguala is one of the few herbs in this collection to have been studied in people: its leaf extract has been tested in clinical studies, including studies in healthy volunteers^{[8, 9]}.

• Healthy-looking skin

  In its native range, calaguala has long been a folk herb for the skin, and modern research on the leaf extract has focused on the skin too. Calaguala supports healthy-looking skin.*^{[3, 8, 9]}

• Antioxidant support for skin

  The leaf is rich in phenolic compounds with antioxidant activity. Calaguala provides antioxidant support for skin.*^{[3, 8, 9]}

• A folk herb from Mexico to Central America

  Studies of local herbal practice in Mexico and Central America record the golden polypody among the plants people use. In Mexico the rhizome is the part in demand: it is sold in local markets under the name calaguala, and the fern is even semi-cultivated for it.^{[2, 7]}

Plant compounds

Calaguala leaf contains phenolic compounds, a large group of naturally occurring plant compounds, many of them with antioxidant activity^{[3, 8]}. The best studied are caffeic acid and ferulic acid, the strongest antioxidants among them in laboratory tests, along with chlorogenic, coumaric and vanillic acids^{[3, 8]}.