Pollination mechanism of Bulbophyllum penicillium. A, A fruit fly (arrow) enters a flower of B. penicillium foraging for food and sets the lip in motion. B, The fruit fly (arrow) drops with the lip. C, The lip moves downwards and then upwards allowing the fruit fly (arrow) to touch the stigma and the anther. D, The fruit fly picks up two pollinia of B. penicillium on its thorax (arrow) after touching the anther. See LIU et al., pp. 102–108 in this issue.