Ragweed (image) Helmholtz Centre for Environmental Research - UFZ Share Print E-Mail Caption Ragweed (Ambrosia artemisiifolia) is native to North America and has already spread to many parts of Europe. Its pollen is one of the most aggressive allergens. Credit Photo: Klaus-Dieter Sonntag,fotoplusdesign.de/ UFZ Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.