Some plants have evolved the capacity to use insects and other organisms for food, which allows them to live in nutrient-poor environments. To this end they have leaves that have been modified into specialized appendages that trap and digest their prey.
One such plant is the pitcher plant, shown below, from the genus Nepenthaceae. This plant has a cup like structure (the pitcher) that has rims and inside surfaces with the consistency of a slippery wax. Insects that venture too far into the pitcher fall into a pool of liquid with digestive enzymes at the bottom of the pitcher and can’t get out. Some pitcher plants have pitchers large enough to trap small animals like mice!
Whereas the pitcher plant is a passive trap, other carnivorous plants like the sundews, which belong to the genus Drosera, have a more active involvement in capturing their food. These plants have leaves sporting tiny spine-like protuberances tipped with a droplet of a sticky liquid. Any insect landing on the leaf gets stuck and triggers a response whereby the leave curls about itself, further trapping the insect, and also secreting digestive enzymes.
But the most active carnivorous plant is certainly the Venus flytrap (Dionaea muscipula). The Venus flytrap has hinged appendages with open surfaces crowned with hairs at the edges. The inside of the surfaces have tiny hairs which serve as triggers. When an insect brushes against the tiny hairs, the 2 surfaces close upon the insect and the hairs at the edges interlock to prevent their scape. As the insect is pressed between the surfaces, the plant secretes enzymes that digest the hapless critter.
If you want to see some of the carnivorous plants mentioned above in action, watch the video below from Gross Science.
The pictures of the pitcher plants in a Walmart store in Florida, and the sundew and Venus flytrap plants at the Rawlings Conservatory in Baltimore are by the author and can be used with permission.