The eastern Asian and eastern North American plant disjunction is a classical biogeographic pattern. This pattern was first noticed by Linnaeus in 1750 and elaborated by Asa Gray in a series of papers between 1840 to 1878. Approximately 65 genera of flowering plants are confined to eastern Asia and eastern North America. Previous studies reported a high level of morphological similarity among the disjunct species and many intercontinental species pairs were proposed. Morphological stasis has been suggested to be common among these disjuncts. Recent phylogenetic analyses confirm the close affinity of taxa in most disjunct genera, but few intercontinental sister-species relationships have been detected. Several disjunct taxa are polyphyletic or paraphyletic, suggesting that the morphological similarities in these groups may be attributable to convergence or symplesiomorphies. Subtropical and tropical taxa (e.g., in Aralia) may be nested within the temperate disjuncts, suggesting the need to examine the eastern Asian eastern North American disjunction in the context of global biogeography. Phylogenetic patterns and results from morphometric analyses in Aralia, Corylus, Osmorhiza, Panax, and Prunus support morphological stasis of the eastern Asian and eastern North American disjuncts via either evolutionary constraints or convergence.

Key words: Biogeography, disjunction, eastern Asia, eastern North America, Northern Hemisphere biogeography