As pretty as the Mexican sunflower may be, this flower is seen to be a problem for those plants surrounding it. This flower, originating in Mexico and Central America, has migrated to a variety of countries due to its pharmacological activity, soil erosion control, and appearance. Unfortunately, the chemicals that the plant produces causes nearby plants to experience developmental issues, deeming the Mexican sunflower an invasive species. One of the compounds extracted from the leaves that possess the phytotoxic properties include the sesquiterpene lactones tagitinin C, pictured above.
Miranda, M. A. F. M.; Varela, R. M.; Torres, A.; Molinillo, J. M. G.; Gualtieri, S. C. J.; Macias, F. A. J. Nat. Prod., 2015, 78, 1083–1092