What basic trap type is used by pitcher plants?

Pitcher plants use pitfall traps. Their modified leaves form deep chambers that lure prey, cause it to slip or fall inside, and retain it in digestive fluid or a microbial community.

Many pitchers attract insects with nectar, bright coloration, scent, or ultraviolet patterns. The rim, called the peristome, can become extremely slippery when wet. Once an insect loses its footing, waxy surfaces, downward-pointing hairs, and the chamber’s shape make escape difficult.

The trapped animal eventually drowns, after which plant enzymes or bacteria break down its body. The plant absorbs compounds such as amino acids, ammonium, and phosphate, supplementing the poor mineral nutrition of its habitat.

“Pitcher plant” describes a form rather than one close evolutionary group. Pitfall traps evolved independently in lineages including Nepenthes, Sarracenia, Darlingtonia, Heliamphora, Cephalotus, and some bromeliads. They are therefore a classic example of convergent evolution, not a type of snap, bladder, or flypaper trap.