Liverworts are ancient green land plants that look like flattened liver-shaped pads, or they have stems and leaves and often get mistaken for mosses, their distant cousins.
The liverworts Pleurozia and Colura also have curious leafy pouches that look uncannily like miniature carnivorous pitcher plants. These liverwort pitchers are tiny, featuring an opening and a lid that moves inwards on a hinge, but then closes tight. When the lid flips open it lets in a tiny creature but then shuts and prevents their escape, making a trap rather like the bladder trap of a carnivorous bladderwort plant. And another curious similarity to a typical carnivorous plant is how the liverworts lure their prey to the traps by some sort of unknown attraction.
In the wild, these tiny liverwort pitchers can be full of microscopic single-celled protozoa and other minuscule creatures. But despite their elaborate traps, the liverworts do not have any digestive enzymes to break down their prey into food they can absorb. Instead, the captured inmates may simply die and get broken down by bacteria, a strategy also used by some carnivorous pitcher plants to feed off their prey.
