Trapping Mechanisms
There are visible parallels between the trapping mechanisms of carnivorous plants and protocarnivorous plants. Plumbago and other species with glandular trichomes resemble the flypaper traps of Drosera and Drosophyllum. The pitfall traps of protocarnivorous plants, such as some Heliamphora species and Darlingtonia californica, are so similar to those of true carnivorous plants that the only reason they may be considered protocarnivorous instead of carnivorous is that they do not produce their own digestive enzymes. There are also protocarnivorous bromeliads that form a pitfall trap in an "urn" of rosetted leaves that are held together tightly. There are also other plants that produce a sticky mucilage not necessarily associated with a tentacle or glandular trichome, but instead can be described more like a slime capable of trapping and killing insects.
Read more about this topic: Protocarnivorous Plant