Pollen grains from most flowering plants are transported by wind or animals and deposited on the receptive surface of the stigma of a different individual, but self-pollination is also common. We have discovered a new process for self-pollination in the laterally orientated flowers of a Chinese herb, in which a film of pollen is transported from the anther (pollen sacs) by an oily emulsion that slides sideways along the flower's style and into the individual's own stigma. This mode of self-pollination is a new addition to the broad range of genetic and morphological mechanisms that have evolved in flowering plants (angiosperms)¹, and may be common in species growing in shady, windless and insect-poor habitats.