Corynaea is a monotypic genus of parasitic flowering plants in the family Balanophoraceae, order Santalales. Its sole species, Corynaea crassa, was first described by Joseph Dalton Hooker in 1856 in the Transactions of the Linnean Society of London; Hooker originally split the material into three species, which were later reduced to synonymy under C. crassa, leaving the genus with a single accepted member. Two varieties are currently recognized: C. crassa var. crassa and C. crassa var. sprucei.
As a root hemiparasite, Corynaea lacks leaves and chlorophyll, deriving nutrients entirely from a host plant through an underground haustorial tuber. Seasonal, club-like inflorescences emerge from this tuber above ground, ranging from yellowish-brown to intense purple or pink, with globose-to-fusiform flower heads a few centimetres across; flowers are pollinated by Hymenoptera and Diptera. The genus is not restricted to a single host: recorded hosts span at least four plant families, including Bocconia frutescens, Myrcia, Cayaponia, Palicourea, Verbesina, and even bamboo.
Corynaea is native to South and Central America, occurring from Costa Rica and Panama south through Colombia, Ecuador, Peru, Bolivia, and Venezuela, typically in primary and secondary forest, cloud forest, and oak forest between roughly 1,250 and 4,000 m elevation. Its subterranean habit makes it easy to overlook, and it has been described as uncommon to vulnerable across its range, a status linked to forest conversion and its dependence on suitable host plants.
The plant is best known outside botany for its traditional use in Peru, where the tuber — sold dried or powdered as "huanarpo macho" — is used in folk medicine as a male aphrodisiac and anti-inflammatory. Its common English name, "Peruvian Viagra," reflects this reputation. Chemical analysis of the tubers has identified anthocyanins, flavonoids, tannins, triterpenes, and steroids, and extracts have shown antibacterial activity against Staphylococcus aureus; regulators in the Philippines have separately warned that some commercial products were adulterated with tadalafil.
Distribution
Native to South and Central America, occurring in Bolivia, Colombia, Costa Rica, Ecuador, Panama, Peru, and Venezuela, including several provinces of Peru (Amazonas, Cajamarca, Cusco, La Libertad, Lambayeque, and Pasco).
Ecology
A root hemiparasite with no host specificity, recorded parasitizing plants in at least four families (including Bocconia frutescens, Myrcia, Cayaponia, Palicourea, Verbesina, and bamboo). Grows in primary and secondary forest, cloud forest, oak forest, and along stream banks, generally between about 1,250 and 4,000 m elevation.
Conservation
Considered uncommon across its native range — partly because its underground habit makes it easy to miss — and has been described as "vulnerable" in at least one report, a status attributed to conversion of native forest to agricultural and pastoral land as well as its dependency on host-plant availability and quality.
Cultural Uses
In Peru the tuber, known as "huanarpo macho," is a traditional folk-medicine remedy used as a male aphrodisiac and anti-inflammatory, sold dried or as a powder, and giving rise to the plant's common English name "Peruvian Viagra." Chemical studies of the tubers have found anthocyanins, flavonoids, tannins, triterpenes, and steroids, with extracts showing antibacterial activity against Staphylococcus aureus; the Philippine Food and Drug Administration has warned that some commercial products were adulterated with tadalafil.
Taxonomy Notes
First described by Joseph Dalton Hooker in 1856 (Trans. Linn. Soc. 22: 31), initially as three separate species that were later synonymized into the single accepted species Corynaea crassa, leaving Corynaea monotypic. Two varieties are recognized: var. crassa and var. sprucei (Eichler) B.Hansen. GBIF confirms the authorship, publication, and placement in family Balanophoraceae, order Santalales.
