From Seed to Seed:
Plant Science for K-8 Educators

Adaptations for nutrient uptake. We have already stated that most plants manufacture their own food by the process of photosynthesis. These plants get the nutrients that they need from the air, water, and soil. However, some plants have lost some or all of their ability to photosynthesize, and must get nutrients from other organisms. Plants that draw food from other living organisms are called parasites. Plants that draw food from dead or decaying organisms are called saprophytes.

Perhaps the most interesting method for meeting nutritional needs is used by carnivorous plants such as sundews and pitcher plants.

Carnivorous plants often inhabit places such as swamps and bogs where available nitrogen is scarce. Since saturated soils are oxygen-deficient, the pace of decomposition of organic matter is extremely slow. It is this decomposition that produces nitrogen in a form available to plants. Plants growing in these nitrogen-deficient environments fill some of their requirements by trapping insects. They then use enzymes to "digest" the bodies of their prey. Although stories of "man-eating" carnivorous plants arise from time to time, the most common prey are insects, mites, and sometimes very small frogs. There are reports of carnivorous pitcher plants that are large enough to capture and digest small frogs and mice, but no specimens big enough to devour humans have been documented...yet!