AbstractSelf-incompatibility occurs widely in the Solanaceae, but a few species in this family, or a few intraspecific populations or a few individuals within the populations are highly self-compatible and their breeding systems have evolved from outcrossing to selfing. We studied pollination biology of Anisodus tanguticus from this family, a perennial endemic to the Qinghai-Tibetan Plateau. This species flowers in the early summer and probably suffers from the serious limitations of the outcrossing pollinator. We aimed to test whether the breeding systems of a few individuals in this species have shifted from outcrossing to selfing. Our experiments and observations were conducted in two populations with different altitudes. Most flowers of this species were incompletely protogynous, and the mean distance between the stigma and anthers decreased gradually with floral longevity. Both stigma and anthers did not come into touch when the corolla wilted in most of the monitored flowers and such herkogamy favours outcrossing. However, the complete contact of stigma and anthers in 4.9% of the measured flowers suggested potential occurrence of “autonomous selfing” in these flowers. Most of the examined individuals in both populations are self-incompatible and have to depend on insects for pollination. However, a few of them were found to be self-compatible. Flies were the effective outcrossing pollinators in the high altitude population and “autonomous selfing” was detected in a few individuals of this population. In contrast, the effective outcrossing pollinators were rarely observed in the low altitude population and the dominant visitors or pollinators, ants in this population, transferred pollen within the single flower, which finally resulted in “facilitated selfing”. Pollination limita-tions were obvious in both populations due to the lack of enough outcrossing pollinators. Two different self-ing mechanisms, uncovered here, may provide a partial compensation for the natural reproduction of this al-pine species in the arid alpine habitats when flowering at the early summer.