Investigation on sexual reproduction and invasion risk of 12 alien Compositae species

Plant species of Compositae exhibit superior sexual reproduction. The introduction of Compositae species for ornamental use may cause a high invasion risk. In this study, we investigated the sexual reproductive traits of 12 ornamental Compositae species. The floral characteristics, pollen viability, pollination system, and seed production were compared among species to assess their sexual reproductive ability and invasion risk. Results showed that most plant species could reproduce without pollinators. In addition, 26 species of insects, categorized into six orders and 16 families, were observed to visit the experimental flowers. Bees were the most frequent pollinators, followed by butterflies and flies. Plant species differed in pollinator assemblage and visitation rate, as well as reproductive success. Considering pollen viability, pollination system and seed production, we regarded Rudbeckia hirta L., Echinacea purpurea (L.) Moench, Coreopsis grandiflora Hogg., and Sanvitalia procumbens Lam. to be successful in pollination and sexual reproduction in this region, with a high risk of invasion. By comparing the sexual reproductive traits among related species, we provide instructions for assessing the invasion risk of introduced plant species.