Title: Germination patterns and implications for invasiveness in three Taraxacum (Asteraceae) species
Abstract: The ability to germinate across different environments has been considered an important trait of invasive plant species that allows for establishment success in new habitats. Using two alien congener species of Asteraceae –Taraxacum officinale (invasive) and Taraxacum laevigatum laevigatum (non-invasive) – we tested the hypothesis that invasive species germinate better than non-invasives under various conditions. The germination patterns of Taraxacum brevicorniculatum, a contaminant found in seeds of the crop Taraxacum kok-saghyz, were also investigated to evaluate its invasive potential. In four experiments, we germinated seeds along gradients of alternating temperature, constant temperature (with or without light), water potential and following accelerated ageing. Neither higher nor lower germination per se explained invasion success for the Taraxacum species tested here. At alternating temperature, the invasive T. officinale had higher germination than or similar to the non-invasive T. laevigatum. Contrary to predictions, T. laevigatum exhibited higher germination than T. officinale in environments of darkness, low water potential or after the seeds were exposed to an ageing process. These results suggested a complicated role of germination in the success of T. officinale. Taraxacum brevicorniculatum showed the highest germination among the three species in all environments. The invasive potential of this species is thus unclear and will probably depend on its performance at other life stages along environmental gradients. [LUO, J. and CARDINA, J. (2012), Germination patterns and implications for invasiveness in three Taraxacum (Asteraceae) species. Weed Research. on-line Jan 02, 2012. doi: 10.1111/j.1365-3180.2011.00898.x]