Dandelion is a cosmopolitan weed of economic and environmental significance because of its negative effects on crop yield and the large amount of herbicides used for its control in agricultural, residential, and recreational areas in North America. Asexual dandelion plants, which are apomictic and produce genetically identical seeds, provide a great experimental model for biological studies, such as examination of its reproductive responses to global environmental changes. In a growth chamber experiment, we investigated how elevated CO2 affected reproduction and seed dispersal properties in dandelion. Dandelion plants were grown at ambient (370 µmol mol−1) or elevated (730 µmol mol−1) CO2 until reproductive maturity. Results showed that dandelion plants examined in our study produced 83% more inflorescences and 32% more achenes, i.e., single-seed fruits, per plant at elevated than at ambient CO2. Seeds from elevated CO2-grown plants were significantly heavier and had a higher germination percentage, leading to larger seedlings and earlier establishment in the subsequent generation. Furthermore, achenes from plants grown at elevated CO2 had characteristics, such as higher stalks at seed maturity, longer beaks, and larger pappi, which would increase the distance of seed dispersal by wind. In addition to these elevated CO2-induced changes in reproductive properties, dandelion has a number of inherent characteristics, e.g., high competitiveness and adaptations to disturbance, that would increase its vegetative and reproductive success in a higher CO2 environment. Consequently, dandelion can potentially become more widespread and noxious as atmospheric CO2 continues to rise because of human activities.
Nomenclature: Dandelion, Taraxacum officinale G.H. Weber ex Wiggers TAROF