Carnivorous plants are plants that attract, catch, and digest animal prey, absorbing the bodily juices of prey for the nutrient content. There are more than 400 species of carnivorous plants. The species are classified according to the nature of their trapping mechanism. All carnivorous plants have traps made of modified leaves with various incentives or attractants, such as nectar or an enticing color, that can lure prey. Active traps display rapid motion in their capture of prey. The Venus fly trap, Dionaea muscipula, and the bladderwort, Utricularia vulgaris, have active traps that imprison victims. Each leaf is a two-sided trap with trigger hairs on each side. When the trigger hairs are touched, the trap shuts tightly around the prey.

Semi-active traps employ a two-stage trap in which the prey is caught in the trap’s adhesive fluid. As prey struggles in the fluid, the plant is triggered to slowly tighten its grip. The sundew (Drosera capensis) and butterwort (Pinguicula vulgaris) have semi-active traps.

Passive traps entice insects using nectar. The passive-trap leaf has evolved into a shape resembling a vase or pitcher. Once lured to the leaf, the prey falls into a reservoir of accumulated rainwater and drowns. An example of the passive trap is the pitcher plant (Sarracenia purpurea). The Green Swamp Nature Preserve in southeastern North Carolina has the most numerous types of carnivorous plants.