The lure and intrigue of Yunquea tenzii Skottsb. (Cardueae: Centaureinae)

Abstract

We discuss the history of the monospecific genus Yunquea , which is endemic to the highly inaccessible peak El Yunque on Robinson Crusoe Island, Juan Fernández Archipelago. The allure of the genus rests largely on the difficulty of reaching the one known population; we trace the history of the few persons who succeeded in climbing to the summit where the genus occurs. The genus remains of interest to botanists because of the lack of flowering material, having been described only from leaves! During the near century since its description, Yunquea tenzii remains a mysterious species. Molecular phylogenetic studies identify the Juan Fernández endemic Centaurodendron and the continental genus Plectocephalus as closest relatives. However, resolution of relationships among the four genera has not been achieved, leaving biogeographic relationships unknown. Whether Yunquea tenzii evolved anagenetically from continental colonists or cladogenetically from a common ancestor with Centaurodendron remains a mystery. Viable seeds have been collected from the natural population, suggesting sporadic sexual reproduction, but lack of mature floral tissue precludes insights into the floral evolution and reproductive biology of Yunquea .