Insectivorous Mode of Nutrition

Insectivorous (carnivorous) plants grow in nitrogen-deficient soils, such as bogs and marshes, and have evolved modified leaves that trap and digest insects to supplement the nitrogen their roots cannot obtain from the soil (Figure 12.12). Nepenthes, the pitcher plant, has a leaf modified into a pitcher containing digestive enzymes, with nectar glands around the rim acting as an attractive lid; once an insect is trapped inside, proteolytic enzymes digest it. Drosera, the sundew, carries long, club-shaped tentacles that secrete a sticky digestive fluid, giving the leaf a dew-covered appearance that both attracts and traps insects. Utricularia, the bladderwort, is a submerged aquatic plant whose leaf is modified into a hollow bladder that sucks in and traps small aquatic prey. Dionaea, the Venus flytrap, has a leaf modified into a colo …