The interspecific relationships of the temperate genus Eupatorium in Northern Hemisphere were assessd by restriction site analysis of chloroplast DNA and karyotype analysis. Molecular and cytological data provided strong evidences that the origin of Eupatorium was in North America and the genus diversified well into three morphological species groups there and extended its range to temperate regions of eastern Asia and Europe. Asian species group is monophyletic. Agamospermous reproduction and hybridization make species recognition very difficult and the distributional range of each species very ambiguous. Cytogeographical study combined with morphological analysis on the agamic complex and related species could reveal the population structure, the discrete circumscription of species, their distributional ranges, and the evolutionary and phytogeographical history in this genus.
PDF Links
Full text via DOI
Download Citation 
