Morphological and molecular evidence for interspecific hybridisation in the introduced African genus Crassocephalum (Asteraceae: Senecioneae) in Asia

The genus Crassocephalum in Asia, introduced there from Africa, was examined by extensive field work, herbarium studies, analyses of pollen and seed fertility, chromosome counts and ITS and trnL-F sequencing. We found that Crassocephalum in Asia comprises two species and their interspecific hybrid. The two species are C. crepidioides (Benth.) S. Moore and C. rubens (Juss. ex jacq.) S. Moore, of which the latter is a new record for Asia (north Thailand). The hybrid between these two species in north Thailand originated from a cross between C crepidioides (2n = 40) as female and C rubens (2n = 40) as male parent.