Natural interspecific hybridization has numerous ecological effects and has been an important driver of evolutionary diversification throughout the history of land plants. Hybridization propensity varies widely among plant groups, but explanations for this variation have not been rigorously tested. Here, we present the first phylogenetically-informed examination of correlates of hybridization in plants. Using phylogenetically independent contrasts, we examined correlations between hybridization propensity and several ecological, morphological, behavioral and life-history traits.

Results/Conclusions

Hybridization propensity was scored for 299 plant families and 3,281 genera by counting hybrids described in >36,000 species accounts contained in eight regional floras. Floras covered parts of North America, Europe, Australasia, and two island groups. We examined perenniality, woodiness, flower morphology, mating systems, and other traits, and found that several of these variables are predictive. The results aid our understanding of the conditions fostering plant diversification, increase power for predicting which groups might be at risk from transgene escape or from extinction-by-hybridization, and may contribute to a better understanding of the differences between evolutionary patterns in animals and plants.