Orchid helps insect get a grip

by Kobe University
July 29, 2022

The wild orchid Habenaria radiata’s pure white petals resemble a white egret in flight (hence its common name white egret orchid). H. radiata has been loved by people since ancient times but the adaptive significance of the flower’s characteristic jagged shape has been unclear until now. A multi-institutional research group has been working for three years to solve this mystery by conducting field experiments in which the feather-like fringe was removed, and detailed behavioral observations of the orchid’s pollinators.

The research collaboration consisted of Associate Professor SUETSUGU Kenji and student ABE Yusuke (who completed his Master’s degree in the 2021 academic year) of Kobe University Graduate School of Science, ASAI Takeshi and MATSUMOTO Shuji of Himeji Tegarayama Botanical Garden, and HASEGAWA Masahiro of Osaka Museum of Natural History.

From the results, they discovered that in their natural habitat, white egret orchids with the fringe removed produced fewer healthy seeds per individual fruit than intact plants. Hawkmoths, which are major pollinators of this orchid, normally grasp onto the fringe with their mid-legs to steady themselves when they drink its nectar, however the researchers observed that the hawkmoth was often unable to do this on plants with the fringe removed. In other words, this fringe functions as a supportive platform for the pollen-carrying hawkmoth. It was previously thought that hawkmoths mainly hover while drinking nectar. Although the white egret orchid utilizes hawkmoths to transport its pollen, these important findings indicate that the eye-catching fringe is more than a visual aid for pollinators, and has evolved to support the hawkmoth while it feeds on the nectar.

Keep reading: https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.3781

Read the Ecology paper: https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.3781