Opisthopappusis a perennial, endemic herb of the Taihang Mountains in China. Two species of this genus (O. longilobusandO. taihangensis) are important wild genetic resources for Asteraceae; however, their reproductive biology has been lacking until now. This study is the first detailed report on the reproductive biology and breeding systems of twoOpisthopappusspecies. Through field observations, the floral syndromes ofO. longilobusandO. taihangensiswere found to possess a similar pattern, althoughO. taihangensishas a relatively larger capitulum, more ray ligules, and disc florets. The flowers of bothO. longilobusandO. taihangensisare protandrous, a character that can prevent autogamy at the single-flower level, and insects are required for pollination. Further, brightly ligules, brightly bisexual florets, unique fragrance, and amount of nectar suggest that these species propagate via an entomophilous pollination system. Hymenopteran and Diptera species were observed as the effective pollinators for these two species. The outcrossing index, pollen/ovule ratio and the results of hand pollination indicated that theseOpisthopappusspecies might have a mixed mating system that combines cross-fertilization and partial self-fertilization forO. longilobusandO. taihangensis, outcrossing predominated in the breeding system, while self-pollination played an important role in seed production when insect pollination was unavailable, particularly in a harsh environment, such as the Taihang Mountains cliffs. Meanwhile,O. taihangensismight better adapt to severe surroundings with relatively complex floral syndromes, specifically through the attraction of visiting insects and a high seed set rate. The above results not only provide reference information toward a better understanding of the survival strategies ofO. longilobusandO. taihangensisin the Taihang Mountains but also lay a solid foundation for further exploring the molecular mechanisms that underly their adaptation under cliff environments.