Wetlands like bogs are often highly acidic due to peat-forming mosses. Acidic conditions make nutrients such as nitrogen, potassium, phosphorous, calcium, and magnesium extremely difficult for most plants to take up through their roots. Plants have evolved to survive these conditions by trapping insects and digesting them to provide the nutrients needed for growth.

      Many of these plants have structural modifications that include rosette shoots, highly modified leaves, and poorly developed root systems (because the leaves gather the nutrients). There are 3 categories of insectivorous plants based on the type of insect trap mechanism used by the plant: passive traps, active traps, and suction traps.

      The pitcher plants such as Nepenthes,Cephalotus, and Sarracenia have passive traps. Insects simply fall into a pit formed by the tubular leaf blades of these plants. The insects may be lured to the traps by various colors, scents, and nectars. Once an insect has fallen into the water-filled trap its escape may be hindered by trichomes or slippery secretions.

      Active traps such as the notorious Venus flytrap react to insects on their leaf surfaces by secreting digestive enzymes. Pinguicula and Drosera, the sundew, have hairs that bend inward and leaf margins that roll up to help trap the insects. Dionaea, the Venus flytrap, has leaf blades with trigger hairs that, when stimulated, will cause the hinged blade to quickly close over an insect.

      The suction traps of Utricularia, the bladderwort, have leaves with small sacs, the bladders. An insect is trapped when it trips hairs around the opening of the bladder. This results in water being sucked into the bladder, carrying the insect with it. Once inside, the insect is digested.