 The prominent synantherologist S.F.Blake, however, much earlier named the genus "Pappobolus" based on species that have a pappus of numerous caducous awns.It was only during the work of Panero on the genus that the congeneric nature of plants of the two pappus types was recognized, and this has subsequently been supported by both molecular phylogenetic studies  and phytochemical analyses.Subsequent studies have shown that the genus is related to members of the subtribe Helianthinae that occur in Mexico, and it is likely that migration into South America only occurred following the closure of the Panamanian land bridge about 3 million years ago.