Pollination biology of the deceptive orchid Changnienia amoena

Haiqin Sun,Song Ge,Ronny Alexandersson,Yibo Luo

doi:10.1111/j.1095-8339.2006.00457.x

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, Botanical Journal of the Linnean Society , 2006, 150 , 165‐175. ADDITIONAL KEYWORDS: adaptation ‐ bumblebee ‐ flowering phenology ‐ fruit set ‐ pollinarium removal ‐ pollinia deposition.

Highlights

Orchidaceae is one of the most species-rich families of flowering plants, comprising an estimated 800 genera and over 25 000 species (Cribb, 2001a; http:// www.kew.org/monocotChecklist/default.jsp)
Among 15 species of anthophilous insects present in the Changnienia amoena community, only bumblebees were found to act as pollinators
The primary effective pollinators are B. trifasciatus at Longmenhe and B. imitator at Guanmenshan, but the pollinarium was attached on the same position of the insect body and the behaviours of the two bumblebees on flowers of C. amoena were essentially the same

Summary

INTRODUCTION

Orchidaceae is one of the most species-rich families of flowering plants, comprising an estimated 800 genera and over 25 000 species (Cribb, 2001a; http:// www.kew.org/monocotChecklist/default.jsp) It is one of the few groups of angiosperm whose high diversity can be explained by its possession of a unique association with pollinating insects, which has resulted in extreme radiation (Nilsson, 1992; Gorelick, 2001). By comparing the pollination modes of C. amoena and Calypso bulbosa, we hope to provide some insights into the diversity of the two species. Such information might provide suggestions for the restoration and conservation management of C. amoena, which is listed as an endangered species in China (Fu, 1992; Xiong et al, 2003)

MATERIAL AND METHODS

C Lateral lobe

Findings

DISCUSSION