Abstract: Flaveria bidentis, an annual weed of Flaveria (Compositae ), had been newly discovered in China. It might be a potential invasive plant in that of its very strong reproductive and survival abilities .Morphology and surface character of the seed were measured , and seed germination characteristics of this exotic species were examined from temperature, light, salinity to seed soaking aspects. The results showed that: the seed of F. bidentis were adapted well to high temperature and germinated rapidly at 35℃. Its germination percentage, germination index and vigor index were increased with the temperature rose. The germination percentage was affected little by light , while germination peak was delayed , and germination and vigor indexes of the seed were reduced with the prolonged light time. Salinity stress had significant effect on seed germination of F. bidentis: the germination percentage and peak decreased gradually with the increasing of NaCl concentration, while the germination and vigor indexes of the seed were higher than those of the control under 0.01mol/L and 0.05 mol/L NaCl stress. Lower NaCl stress promoted the elongation of the radicle. Seed soaking also had notable impact on seed germination. In all, it was suggested that, the extremely high germinability and preference to salinity of the seeds of Flaveria bidentis could be closely related with its strong invasiveness.

Key words: Flaveria bidentis