Intercontinental dispersal of Typha angustifolia and T. latifolia between Europe and North America has implications for Typha invasions

The full effects of biological invasions may be underestimated in many areas because of cryptogenic species, which are those that can be identified as neither native nor introduced. In North America, the cattails Typha latifolia, T. angustifolia, and their hybrid T. × glauca are increasingly aggressive invaders of wetlands. There is a widespread belief that T. latifolia is native to North America and T. angustifolia was introduced from Europe, although there has so far been little empirical support for the latter claim. We used microsatellite data and chloroplast DNA sequences to compare T. latifolia and T. angustifolia genotypes from eastern North America and Europe. In both species, our data revealed a high level of genetic similarity between North American and European populations that is indicative of relatively recent intercontinental dispersal. More specifically, the most likely scenario suggested by Approximate Bayesian Computation was an introduction of T. angustifolia from Europe to North America. We discuss the potential importance of our findings in the context of hybridization, novel genomes, and increasingly invasive behaviour in North American Typha spp.