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Pappobolus
''Pappobolus'' is a genus of flowering plant in the sunflower family native to the Andes Mountains of Colombia, Ecuador, and Peru.〔Panero, J. L. 1992. Systematics of ''Pappobolus'' (Asteraceae-Heliantheae). Systematic Botany Monographs 36: 1-195.〕〔(Tropicos, Pappobolus S.F. Blake )〕
''Pappobolus'' is distinguished from closely related genera by its combination of shrubby habit and usually caducous pappus. Within the genus there is considerable variation in the pappus, a structure that has traditionally been considered a key to defining genera in Asteraceae, and this led to earlier confusion in defining the genus. Most of the species of the genus were originally described as members of ''Helianthus'', based on having a pappus of two caducous awns. When it was recognized that they were not part of the exclusively North American ''Helianthus'', they were transferred to a genus called ''Helianthopsis''.〔Robinson, H. 1979. Studies in the Heliantheae (Asteraceae). XVIII. A new genus ''Helianthopsis''. Phytologia 44: 257-269.〕 The prominent synantherologist S.F.Blake, however, much earlier named the genus ''Pappobolus'' based on species that have a pappus of numerous caducous awns.〔S. F. Blake. 1916. ''Pappobolus macranthus''. Hooker's Icones Plantarum 31: plate 3057.〕 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 〔Schilling, E. E. and R. K. Jansen. 1989. Restriction fragment analysis of[chloroplast DNA and the stystemics of ''Viguiera'' and related genera (Asteraceae: Heliantheae) American Journal of Botany 76: 1771-1780.〕 and phytochemical analyses.〔Spring, O., J. L. Panero, and E. E. Schilling. Chemotaxonomic analysis of ''Pappobolus'' (Asteraceae: Heliantheae). Biochemical Systematics and Ecology 20: 671-684〕 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.〔Schilling, E. E., J. L. Panero, and U. H. Eliasson. 1994. Evidence from DNA restriction site analysis on the relationships of ''Scalesia'' (Asteraceae: Heliantheae). American Journal of Botany 81: 248—254.〕 Thus, the genus has exhibited an amazing burst of radiation in producing the relatively large number of species, a result in part that reflects the highly dissected montane topography of the Andean region.
;Species〔
==References==
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