a, Green rosette of assimilating leaves (on top) and a large bundle of root-like subterranean leaves acting as traps. b, A single Genlisea trap with protozoa attracted and concentrated around the utricle and the tube. c, Scanning electron micrograph of the tube after a ‘feeding’ experiment with Paramecium caudatum, fixed with osmium tetroxide. Captured protozoa are visible. The rows of long hairs prevent escape.