Pollination biology of the deceptive orchid Changnienia amoena

Abstract

The pollination biology of Changnienia amoena, an endangered terrestrial orchid, was investigated at two sites in the Shennongjia Mountains, Hubei, central China. The results show that the orchid is exclusively pollinated by bumblebees. In Longmenhe, Bombus (Diversobombus) trifasciatus is the primary effective pollinator, whereas B. (Tricornibombus) imitator is the only pollinator in Guanmenshan. These two bumblebees can be treated as a functional group because they carry pollinaria on the same position on their bodies and have similar pollinating behaviours. The morphological traits of the flower adapt precisely to the pollinators. Visitation by bumblebees is mainly in the first half of the flowering period of C. amoena. Pollinarium removal and pollinia deposition take place when bumblebees withdraw from the flower. Crossing experiments show that C. amoena is a self-compatible and outcrossing species. Fruit set in this species is low and may result from limited pollinators because 87.5% of individuals set fruits under hand-pollination, but only 6-12% of individuals set fruits under natural conditions. These results imply that it is important to conserve the pollinator community together with the plants when conservation management for this endangered species is undertaken. Artificial pollination would also be a useful measure to facilitate restoration of the small populations. © 2006 The Linnean Society of London.