The plant that can count to five

A Venus flytrap needs two touches to its trigger hairs within about 20–30 seconds before it snaps shut — a single touch won't do, saving energy on false alarms. Further touches after closure ramp up digestive enzyme production, meaning the plant effectively counts stimulation to decide how hard to digest whatever it just caught.

— Rainer Hedrich et al., The Venus Flytrap Dionaea muscipula Counts Prey-Induced Action Potentials to Induce Sodium Uptake — Current Biology, 26(2), 286–295 (2016)