1. The fitness of ramets or the whole clone may decline with risk spreading, although clonal plants can benefit much from clonal integration or division of labor. Whether clonal plants can alleviate these negative effects by severing stressful ramets as trees litter their old leaves and lower shading branches for resource economy deserves further research. 2. We determined whether an invasive clonal plant (Alternanthera philoxeroides) could selectively detach ramets subjected to extreme stress, thereby optimizing resource allocation and benefiting the remaining unstressed ramets. We named this functional trait anti-clonal integration, corresponding to the term clonal integration. 3. The results showed that the percentage of anti-clonal integration in A. philoxeroides increased with the stress duration. Furthermore, this percentage was greater under drought stress compared to shading or combined drought and shading stresses, and it was greater when the apical ramets were stressed than when the basal ramets were stressed. Moreover, the alive unstressed ramets benefited significantly from anti-clonal integration, and this benefit was greater when the apical ramets were stressed compared to when the basal ramets were stressed. 4. These findings suggested that clonal plants could optimize their resource allocation to enhance the fitness of the entire clones through anti-clonal integration under extreme stress conditions. Moreover, clonal plants may adopt either anti-clonal integration or clonal integration strategies to adapt to stressful environments depending on the stress intensity, thereby gaining competitive advantages. Nevertheless, whether this functional trait of anti-clonal integration applies to all clonal plants remains unclear, thus warranting further investigation. 5. Synthesis. We provide evidence that clonal plant A. philoxeroides could optimize their resource allocation to enhance the fitness of the entire clones through anti-clonal integration under extreme environmental stress conditions.