The pitcher plants falls into the carnivorous plant category. Pitcher plants grow in wet, acidic soils in bogs, savannas and wetlands where the nitrogen levels tend to stay very low. Since nitrogen remains critical to most plants' survival, pitcher plants adapted to the situation by evolving into carnivorous plants that capture and eat insects to obtain the nitrogen.
Two types of pitcher plants exist in nature including the American pitcher plant (Sarracenia sp.) and the tropical pitcher plant (Nepenthes sp.). The American pitcher plant includes nine different species. The tropical pitcher plants break down into categories including those that grow below 3,000 feet in hot, tropical climates and those that grow above 3,000 feet in elevation with warm days and cool nights.
Tropical pitcher plants grow in the Asian rainforest as well as in India and Australia. American pitcher plants primarily grow along the coastal United States, including Alabama and North and South Carolina. One other American pitcher plant grows along the Eastern seaboard and into the upper Midwest and much of Canada.
The American pitcher plant captures its prey through leaves that develop into tubes. Sweet nectar in the tubes attracts insects that then fall into the trap. Hairs pointing downward stop the insects from climbing back out of the trap. Eventually, the insect dies from a lack of food and water or exhaustion. As the insect decomposes, it gets absorbed by the digestive enzymes found at the base of the trap. The plant absorbs the nutrients through its leaves.
Tropical pitcher plants mostly consist of lianas, or vines, growing on trees. They also grow as rosettes. The unique plant structure includes leaves modified as a trap. The leaf holds liquid used to drown any insects that climb inside. Similar to the American pitcher plant, as the insect decomposes, the plant takes in the nutrients through its leaves.
A few insects adapt to living in the pitcher plant, including mosquitoes and frogs that lay their eggs in the liquid but do not experience any effects of the digestive enzymes. These insects rely on the other insects the plant captures to provide them with a food source. Mosquito larvae eat the tiny protozoa that live in the water. The protozoa eat the bacteria that decomposes the dead insects, creating molecule-sized pieces that the plant absorbs as food.
Pitcher plants growing in gardens help attract unwanted insects, such as ants, flies and wasps. The plants provide showy and unusual displays, perfect for gardens needing more visual interest or an unusual focal point. Pitcher plants also offer a great way to teach children about carnivorous plants and their role in the botanical world.