Temperature inducible phenotypic plasticity is a major player in plant responses to climate warming. Functional responses and their role in determining thermal plasticity of plants remain poorly understood. Our objective was to compare trait responses of six populations of Ludwigia peploides resulting from seed from Oceanic climate and from Mediterranean climate after an exposure at three temperatures (16, 24, and 30°C). A comparative analysis showed that at 30°C, the six populations of L. peploides shared different morphological responses, whereas a common pattern of morphological responses was found for the six populations at 16°C. At 16°C, the growth was very low suggesting a stress. At 30°C, the three Mediterranean populations of L. peploides accumulated ≈ sevenfold more total biomass than the populations from Oceanic region. Despite drawing similar response pattern to temperature, the populations showed several different metabolic responses. The thermal plastic responses to the highest temperature differed according to the origin of the populations. The Mediterranean populations of L. peploides could be better adapted to rising temperature. These abilities could allow them to take advantage from climate warming if the temperature is not warming up to temperature above a critical threshold.