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Insectivorous Plants
Some autotrophic plants, although capable of photosynthesis, take in food in an organic form. They are called insectivorous plants because they “eat” insects. These plants usually live in place such as bogs with soil low in nitrogen and other elements. Insects are an added source of these elements for the plants. Because insectivorous plants can synthesize food, they do not require insects as food for their survival.
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One type of insectivorous plant is Venus’s-flytrap (a). The upper part of a leaf of this plant is bordered by spines and is hinged along a midrib. There are sensory hairs on the upper surface of each leaf lobe. When these hairs and stimulated by the touch of an insect, the leaf quickly closes and traps the insect. Then, digestive enzymes are secreted into the hollow formed by the lobes, and extracellular digestion of the insect takes place. The digested molecules are absorbed and transported throughout the plant.
Other insectivorous plants include the sundew plant (b) and the pitcher plant (c). Sundew plants trap insects differently from Venus’s-flytraps. Long “tentacles” extending from the leaves secrete a sticky substance that traps small insects. Then, the “tentacles” bend inward toward the center of the leaf where the insect is digested. Pitcher plant leaves from pitcherlike structures. Insects are attracted to the pitchers and fall into the traps where are digested by enzymes.
áËÅ觢éÍÁÙÅ : Biology living systems. Page 441.
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