Home Biological science How slender pitcher plant stepping stones fall prey to fate

How slender pitcher plant stepping stones fall prey to fate


The slender pitcher plant, Nepenthes gracilisis a particularly intelligent carnivorous plant.

Like other pitcher plants, it uses a long, slippery funnel to capture its prey. Once an insect has fallen into the tube of the plant, it will not come out again.

But slender also comes with a lid. An insect is attracted to the underside of the leaf at the top of the funnel. Then, when a falling raindrop – very common in the jungles of the plant’s native Southeast Asia – lands on the lid, the weight causes it to snap shut. The sudden movement knocks the insect down the deadly funnel of the pitcher plant.

This springboard mechanism, using external energy as it does, is an absolute boon to the plant. A study published in Biology Letters explains how smart he is.

The pitcher plant uses raindrops to capture prey. Credit: Anne-Kristin Lenz

The researchers, based at the University of Bristol, UK, examined 3D scans of the slender pitcher plant capturing its prey. They watched the way the plant twisted as the lid gently closed and reopened.

The slender pitcher plant, Nepenthes gracilis. Credit: Dr. Ulrike Bauer

To their surprise, they discovered the secret of the lid’s springboard located deep in the tube of the pitcher.

“If you look at the shape of the pitcher, you would assume that the deformation occurs at the smallest cross-section, which is the transition point from the lid to the tube of the pitcher, but in fact it also deforms further down the back. pitcher tube,” says lead author Anne-Kristin Lenz, a PhD student at Bristol’s School of Biological Sciences.

This gives him some advantages. This makes the spring direction-dependent: falling quickly, but rising slowly. It also prevents the lid from twisting or wobbling, which means more energy can be used to close the lid.

Researchers looked at a similar pitcher plant, Nepenthes rafflesiana – but found it lacked these mechanisms.

Nepenthes gracilis uses small changes in the shape of the trap to transmit impact energy with amazing efficiency,” explains Lenz.

Pitcher plant photo, close up with ants under the leaf, next to two 3d images of pitcher plant with top and bottom lid highlighted
Pitcher plant movement imaging. Credit: Anne-Kristin Lenz

“We can learn from these factories how to geometrically optimize structures, which could help save material and weight, while having a functional spring.

“The springboard’s trapping mechanism could even inspire the design of new mechanical devices to harvest energy from rain or hail.”

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