CARNIVOROUS COUNTDOWN

A fly, drawn to the scent of honey-sweet nectar, buzzes too close to a Venus flytrap. One wing grazes a sensitive hair. Nothing happens. A few seconds later, it touches the same hair again. Snap!

INSIDE THE TRAP

Inside the trap, it's dark. The fly keeps buzzing, brushing the hairs as it tries to escape. But the Venus flytrap doesn't start eating yet. Digesting a fly takes energy, and the plant doesn't want to waste energy on a false alarm. So it bides its time.

THE COUNTING GAME

When does the plant know it's trapped a fly—not dust or a raindrop? Only a fly will keep moving long enough to repeatedly trigger the trap's hairs. The flytrap waits until the hairs are touched five times in succession, each within twenty seconds, before secreting digestive enzymes.

ENERGY ECONOMICS

This is an ingenious way for the flytrap to weigh energy costs against meal size. A smaller insect might not reach the five-hair milestone, escaping when the trap reopens. But a juicy, thrashing fly will seal its fate, signaling it's worth the effort.

PLANTS THAT COUNT

Remarkably, Venus flytraps can count to five—and by extension, to four, three, two, and one. A flower that can count? It's beyond what most people imagine plants capable of. But Venus flytraps aren't alone in this ability.

OTHER COUNTING PLANTS

The Andean flower Nasa Possiminia counts too, measuring intervals between pollinator visits to time when to reveal its nectar. Mimosa pudica, the sensitive plant, can remember a learned response for over 40 days. Plants nibbled by herbivores remember for years, priming against future attacks.

PLANT MEMORY

Botanists use terms like "priming," "acclimatizing," or "conditioning" for plants drawing on past experiences to direct future behavior. Is this botanical memory? We have much to learn about this phenomenon.

UNIQUE PLANT INTELLIGENCE

As with all aspects of plant intelligence, plant memory is very different from ours—it evolved to address the specific conditions of life as a plant.