The establishment of non-native species and the increase in atmospheric CO2, in combination, have the ability to alter current ecosystems. Previous studies have shown that invasive species tend to respond more strongly to CO2 than natives, but these comparisons have been of different and unrelated species. To assess how response to CO2 might be related to invasiveness per se, we compared a native (Typha latifolia) with a congeneric invasive (Typha angustifolia), as well as their hybrid (T. × glauca). All three taxa are common components of wetland vegetation, often occurring in near monocultures. An open-top chamber experiment was used to examine the effects of elevated and ambient CO2 concentrations on the three taxa. All three increased rhizome biomass by 40% in elevated CO2. Although the absolute increase did not differ among taxa, the invasive T. angustifolia had a much higher proportional response in biomass and photosynthetic rate (45 and 40% respectively). The weaker response of the two larger taxa native T. latifolia (16 and 2%) and hybrid T. × glauca (-4% and -1%) was possibly driven by soil nutrient deficiency, such that they were not able to benefit from increased CO2. However, under low nutrients the smaller species T. angustifolia may become more a problematic invader in the future.