The New Zealand hebes (Scrophulariaceae) are members of a large Southern Hemisphere clade nested within Veronica.Analysis of ITS and rbcL sequences suggests that the New Zealand species are derived from a single common ancestor that arrived via long-distance dispersal.After the establishment of this initial founder population in New Zealand, the hebes have undergone at least two major episodes of diversification, giving rise to six clades. The combined effects of inbreeding, genetic drift, and strong selection on small populations that were subsequently fragmented by mountain building and glaciation have probably contributed to their rapid diversification.Hybridization and polyploidy are two common means by which the hebes have overcome the effects of the initial genetic bottleneck.The great degree of morphological diversity in the New Zealand hebes contrasts with corresponding low level of sequence divergence.New Zealand was a source of new emmigrants to other regions in the south Pacific that were preadapted to high mountains or forest margins.Our results suggest that two instances of long-distance dispersal from New Zealand to South America, at least one instance from New Zealand to Australia, and one instance from New Zealand to New Guinea have occurred relatively recently.Shorter hops to the Chatham Islands and the subantarctic islands are also supported by the sequence data.