Alpine Codonopsis convolvulacea (Campanulaceae) provides multiple rewards to its main pollinator.

Background:In addition to being a food source, flowers provide non-obvious rewards to their pollinators, such as heat or shelter. However, these rewards have seldom been studied. Aims:Plant–pollinator interactions between an alpine plantCodonopsis convolvulaceaand its main pollinator, a bee (Andrenasp.) were characterised. Methods:We recorded the floral biology and floral visitors in three populations ofCodonopsis. Pollination treatments were conducted to evaluate the importance of insect visitors. Results:The bee was the only visitor to two populations, and the main visitor to a third population. Females visited flowers to collect pollen, while males had a multi-faceted relationship with flowers. Nectar was the food resource of males. When the air temperature was <18 °C, they slept on flowers. During the day flowers were bowl-shaped solar collectors (1–3 °C warmer than the ambient air), and flowers were closed at night. Copulation was occasionally observed on flowers. Although flowers lasted 2 days and males were active for 3 h per day, the high visiting frequency (19.8 per flower per hour) guaranteed pollination of each flower. Conclusions:We suggest that the combination of multiple rewards protect males from cold and unstable weather conditions and encourage them to visit more flowers, and that the specialised pollination system is promoted by the harsh alpine environment. [ABSTRACT FROM AUTHOR]