LAUSR

Cattails (Typha spp.) are essential components of wetland around the world, although they can also be problematic invaders. In some regions of North America, T. latifolia and T. angustifolia hybridize to produce T. x glauca, which is invading and dominating wetlands around the Laurentian Great Lakes. However, in other regions such as China and the maritime provinces of Canada, hybrids are either non-existent or maintained at very low frequencies, and cattails are not considered invasive. Little is known about cattail hybrids in Europe. We used microsatellite markers to characterize T. latifolia, T. angustifolia, T. laxmannii, and T. domingensis sampled from 63 sites across nine European countries. Hybrids were very uncommon (<2% of all sampled plants), and resulted from crosses involving two of T. latifolia, T. angustifolia and T. domingensis. Infrequent hybridization may partly explain why Typha does not dominate European wetlands. However, we identified two distinct genetic clusters within T. angustifolia, broadly corresponding to eastern and western Europe. In addition, our T. laxmannii samples were from countries where it is considered alien, and populations show a high degree of genetic differentiation that is consistent with independent introductions. Managers should continue to monitor range expansions of Typha spp. in Europe, partly because novel interactions among species and lineages may increase the likelihood of future hybridization.