In areas where soil is poor with few nutrients, carnivorous plants have the ability to trap insects, digest them and absorb the nutrients contained within the prey.These plants still carry out photosynthesis to obtain energy however, but, their leaves are modified into traps to obtain their prey. The nutrients nitrogen and phosphorus which they gain by capturing prey allow them to be more efficient at photosynthesis when the soil is nutrient--poor. Pitcher plants and fly traps are two types of carnivorous plants. Many grow in areas such as bogs. Carnivory will supplement the nutrients available to the plant, however, doesn't replace photosynthesis as a way to obtain energy.
Most green plants derive their nitogen from the soli as solutes conducted through the root system.However,some of them obtain nitrogen from captured animal prey.Such plants which get their nitrogen from animals are called carnivorus or insectivorous plants.These plants usually grow in water logged and swampy soils deficient in nitrogenous compound.They have poorly developed roots and thus,they have to depend on captured insects for their nitrogen requirement.
In fact,these plants do not live solely on the captured animals as they can manufacture their own organic food with the aid of chlorophyll present in their leaves and stems.