Plant collections conducted in connection with ethnobotanical studies carried
out with the Guaraní peoples of Misiones Province, Argentina, resulted in the discovery
of a new species of Hypericum L. (Hypericaceae), which is characterized by
its epigeous herbaceous scions produced seasonally from subterranean stems or
roots. This species, H. robsonii H. A. Keller & S. Crockett, is described and illustrated
for the first time. Information about its ecology, habitat and distribution,
phenology and ethnobotany is provided.