Fragmentation caused by disturbance is frequent in wetlands and usually co‐occurs with increases in cadmium and nutrient availability. However, whether fragmentation can interact with nutrients and heavy metals to affect wetland invasive plants has been little studied. We conducted a greenhouse experiment to test the effects of fragmentation (initial fragment was non‐severed, was severed into two fragments, and three fragments), cadmium (low, medium, and high), and nutrient availability level (high and low) on the growth of a widespread, invasive clonal plant Alternanthera philoxeroides (Mart.) Griseb. Clonal fragmentation reduced the total mass, stolon mass, root mass, and total stolon length of A. philoxeroides and altered the biomass allocation. Increases in cadmium adversely affected the growth of A. philoxeroides. The high level of cadmium increased leaf mass ratio but decreased stolon mass ratio. Response of leaf mass ratio to fragmentation varied at different cadmium or nutrient availability levels. Fragmentation, cadmium, and nutrients had a significant interaction on leaf mass ratio. Our results suggest that fragmentation can adversely affect the growth of A. philoxeroides. The adverse effect of fragmentation was greater at high nutrient levels and high cadmium levels (0.4 and 2 mg L−1).

Heavy metal pollution is becoming a serious problem in wetland and often co-occurs with nutrient availability and light conditions variation. We hypothesized that nutrient availability and light condition can affect the growth of wetland plants under heavy metal stress. To test this hypothesis, single ramets of a common, clonal wetland plant Hydrocotyle vulgaris were grown for four weeks at three levels of cadmium with three levels of nutrient availability under 30% or 100% light conditions. High level of nutrient availability and high light condition overall promoted growth of H. vulgaris under Cd stress. Under the two light conditions, responses of H. vulgaris to Cd treatments differed among three nutrient levels. Under 30% light condition, 2 mg L-1 Cd2+ treatment decreased total mass at the low nutrient level and decreased ramet number at the medium nutrient level; 0.5 and 2 mg L-1 Cd2+ treatments decreased leaf mass ratio at the low and the medium nutrient levels. Under 100% light condition, 2 mg L-1 Cd2+ treatments significantly decreased total mass at the high level of nutrients; 2 mg L-1 Cd2+ treatment decreased ramet number at the medium and the high nutrient levels and decreased leaf mass ratio at the medium nutrient levels. Our results suggested that Cd stress can interact with nutrient availability and light condition to affect the performance of wetland plants such as H. vulgaris.