In some sites of Central Italy wild sunflowers are spreading from marginal areas into cropped fields. Crops like maize, tomato, tobacco, alfalfa are often infested with wild sunflowers. Hybrid sunflower crops are also infested with wild material. Plants and populations of wild sunflower also spontane ously grow at the edge of the fields, and along the ditches and roads. We have observed that wild sunflower is partially dispersed by its seed, but possibly it can propagate vegetatively by its perennial basal stalk when it survives the mild winter seasons. We have evidence that sunflower seeds maintain germination capacity for years after being plowed into the soil. This wild sunflower phenotypically resembles H. annuus, but the strong root system is not usual for an annual sunflower species. Concerning its origin, we observed variations indicating naturalization by either an introgression process involving wild species or a segregation of a hybrid variety and the enrichment of genes conferring seed dispersion and root persistence. It is pos sible that a similar process occurred a few centuries ago, after its introduction to Europe when sunflower escaped botanical gardens and began to colonize Eastern European areas.