Raindrops cause self pollination in deceptive orchid Acampe rigida

A recent paper in Annals of Botany by professors Xu-Li Fan*, Spencer C. H. Barrett**, Hua Lin*, Ling-Ling Chen*, Xiang Zhou* and Jiang-Yun Gao*highlighted in Science News, Aug 3, 2012
demonstrated that raindrops striking Acampe rigida flowers can cause self pollination.

Raindrops striking Acampe rigida flowers, flicked away the anther cap exposing the pollinarium and then subsequent drops caused pollinia to be ejected upwards with the strap-like stipe pulling them back and causing them to fall into the stigmatic cavity, resulting in self-pollination. The figure below showes (A) Inflorescence with vertically orientated, bowl-shaped, spirally
arranged flowers. (B) Infructescence illustrating high fruit-set. (C)
Flower with fleshy sepals and petals. (D) The structure of the
pollinarium and stigma: P, pollinia; St, stipe; V, viscidium; R,
rostellum; S, stigmatic cavity.

rain pollination of orchid flower

Reproductive features of the deceptive orchid Acampe rigida.

* Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences,

Mengla, Yunnan 666303, China

** Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto Ontario, M5S 3B2, Canada