While stories of giant, man-eating plants in the deep, inner recesses of the Amazon basin are far-fetched figments of adventure stories, there are several types of carnivorous plants endemic to the area that feed on smaller prey. They range from plants with simple traps that act passively to catch insects, to traps that spring into action to capture a potential meal. Often growing in nutrient-poor soil, these plants need the supplemental nutrition to survive.
Several species of the Utricularia family, better known as bladderworts, inhabit the Amazon area. These are emergent aquatic plants that have an interesting trapping mechanism. They possess hundreds of little round sacs along their underwater branches. Each sac is pressed flat and has a trap door on one end with a trigger. If a tiny crustacean copepod, or other small animal, happens across the plant and grazes the trigger, the sac will expand, sucking the copepod into the sac. The door then closes on the animal for good. It is then digested.
The Drosera family are the sundew plants and are common in Amazonia. They possess the perfect combination of a passive and active plant trap. Sundew plants have flat, teardrop-shaped leaves that grow along the ground, radiating from the center of the plant. At the end of each leaf are dozens of thin tendrils that project from the upper surface of the leaf. Each tendril, in turn, is tipped with a tiny dot of sticky nectar, which attracts insects. Once the insect touches the nectar it is stuck. This may seem a sufficient enough way to catch prey. However, the sundew has another surprise. As the insect struggles to get free, sensors in the plant trigger the leaf to begin to fold in on itself. More of the tendrils are brought into the center of the leaf, further ensnaring the insect, so that there is no escape. Digestive enzymes are then released by the leaf to break the prey down and provide nutrition for the plant.
Members of the Genlisea family of carnivorous plants can also be found along the Amazon. These plants employ a purely passive approach to capturing prey for food. They grow in very wet environments. Their traps, like the bladderworts, are underwater or in muddy conditions. The plant forms stolons, branches that grow underground or underwater. These stolons are hollow tubes with several openings on the ends. Part way up each stolon is a digestive node. When a prey animal inadvertently enters one of the openings in the stolon, specialized hairs in the tube pointing inward and upward prevent the animal from backing out. It will only be able to go forward and will eventually reach the digestive node, where enzymes will convert the prey to food for the plant.
Pitcher plants that are found in the Amazon region include the bromeliads such as members of the Heliamphora family and Brocchinia hechtioides, B. reducta, and Catopsis berteroniana. While the latter three are not true pitcher plants, lacking the typical goblet or bottle-shaped leaves of Heliamphora, these epiphytic plants capture insects in a similar manner. Pitcher plants are capable of holding small wells of water within their leaves. These leaves are often coated with a slippery, waxy substance. Often, directing hairs pointing into the plant are also strategically placed inside the leaves. When a prey animal enters, it will eventually fall into the water held in the bottom of the leaf, where it will be digested and feed the plant.