Botanical identification of plants sold as Hypericum perforatum L. (St. John´s wort) in the informal and formal marketplace in the state of Rio de Janeiro, Brazil

Resumen

The present paper aimed to analyze seven samples of Hypericum perforatum L., popularly known as St. John's wort, marketed as natural antidepressants, collected from formal and informal markets in different municipalities in the state of Rio de Janeiro, Brazil. Morphological and histological analyses were performed on the samples using standard methods for botanical identification, with the aid of a stereoscopic microscope, and binocular and trinocular light microscopes, in addition to specialized literature containing identification keys for the identification of genera and species of the Asteraceae family. Six of the analyzed samples corresponded to an herbaceous species with capitula, petiolate leaves, and both non-glandular and glandular trichomes, which allowed their identification as Ageratum conyzoides. Another sample exhibited characteristics such as glabrous branches, petiolate leaves, a yellowish capitulum, and heteromorphic achene-type fruits, allowing its identification as Synedrella nodiflora. Therefore, it was concluded that none of the samples marketed as St. John's Wort corresponded to Hypericum perforatum L. Consequently, the medicinal claims associated with these plants are invalid, and their use may represent a potential health risk to consumers.