Hollywood has produced plenty of scary movies about flora attacking people, but none has given a plant the power inherent in the Venus flytrap: the ability to count.
The carnivorous plant that catches its prey (usually flies and other airborne insects) in a mouth-like set of leaves doesn't just shut its trap every time something touches the fine hairs on those leaves. Instead, a scientific team led by Dr. Rainer Hedrich of Germany's University of Würzburg have proven that the plant "counts" before it commits to certain actions. It closes on prey only if the hairs are touched at least twice in a 20-second span. Also notably, it bases its digestive process -- releasing the chemicals inside the trap that dissolve the prey -- on how many times it receives electrical signals from the trap.
In other words, the more times the captured creature tries to escape, the larger it believes the creature is and the more digestive enzymes it produces. Because plants don't have nervous systems, they rely on electrical signals to determine their behavior. "A single cell can be electrically excited," Hedrich said.
Other scary plants:
- Some carnivorous plants use tentacles to catch prey; one species of sundew catches prey on its tentacles, which then fling the prey inward to be eaten.
- Butterworts produce a sticky goo that covers their leaves, catching any insects that happen to land on a leaf.
- Most of the approximately 600 types of carnivorous plants live in areas where they can't get nutrients from the soil, thus the need to catch living prey.