Clonal Structure of Invasive Cattail (Typhaceae) Stands in the Upper Midwest Region of the US

There is mounting evidence that the clonal dynamics of foundational plant species, including exotic invaders such as hybrid Typha x glauca , have a profound effect on wetland function. Here, we report on the clonal structure of five intensively sampled Typha stands from the Upper Midwest region where invasions have been especially disruptive. Each of these stands consisted of a large proportion of F 1 hybrids between T. latifolia and T. angustifolia , although backcrosses to both parents were also observed, and provided a means of determining relative age of invasion. We found clonal richness, measured as the proportion of ramets representing distinct genets, to vary positively with age of invasion over a range from 0.20 to 0.45, whereas Simpson’s Evenness was relatively consistent among sites due to a pattern of dominance by a few large clones accompanied by many smaller clones. Ramets were significantly clumped within genets over a range of approximately 20 m, although many clones included ramets separated by as much as 60 to 90 m, suggesting some degree of clone fragmentation over time. Related genets were significantly clumped over approximately 10 m, suggesting that seedling cohorts may frequently recruit in close proximity to one another.