Abstract:The fruits of the Italy cocklebur (Xanthium italicum Moretti) and stab cocklebur (X. spinosum Linnaeus), two kinds of invasive plants in Xinjiang, begin to fall after it matures in late autumn. Some of the fruits detach from mother plant and drop onto dry ground, some fall in the water, and others remain on the branches and do not detach until the next spring. The habitat to which seeds are exposed to in winter directly affects seed germination in the following year. To assess their invasiveness, predict their potential distribution area, and provide scientific guidance for effective prevention and control of these invaders, four kinds of natural winter habitats in which seeds might be exposed in Xinjiang were simulated (i.e., cold flowing water, cold dead water, cold dead water followed by freezing, and cold dry soil or cold air). Treatments in which seeds were soaked in frequently changed cold water (5 ℃), soaked in still cold water (5 ℃), frozen in the air less than-20 ℃, and soaked in still water for 24 h then frozen with the water less than-20 ℃were designed. Seeds kept at dry room temperature served as controls. After 90-day pretreatment, seed germination experiments were conducted. The results showed that: (1) For the Italy cocklebur, the germination percentage of seeds soaked in unchanged cold water was significantly lower than other treatments. Others were not significantly different. (2) For stab cocklebur, seeds that were stored at dry room temperature and frozen in the air had the highest germination percentage (70%), and germination percentage of the seeds soaked in changed and unchanged water was 37% and 65% lower than that of the control. The soaked and frozen seeds did not germinate. It was suggested that multiple habitats, including those with moderate moisture, and wet and seasonally flooded habitats throughout Xinjiang should be strictly monitored for Italy cocklebur, including farmland, understory, roadsides, riversides, and around lakes and reservoirs, which might be potential invasion areas. The key monitoring area for stab cocklebur should have moderate moisture and dry habitats at low latitude and low elevation. The quarantine of imported goods in international ports around southern Xinjiang should be strengthened.