bio

Thigmonasty

A plant's rapid movement in response to touch, where the direction of movement is set by the plant's structure rather than by the direction of the stimulus. *Mimosa pudica* folds its leaves within a second or two; the Venus flytrap snaps shut in under a tenth of a second. The notable part is that they do it without muscle and without nerves: sudden ion movements drive water out of specialised cells, and the signal propagates as genuine action potentials running through ordinary plant tissue. So a fast-moving plant is not, by itself, evidence of animal ancestry.