Pitcher Plants
Also called carnivorous plants, pitcher plants typically live in the tropical areas of South China, the Philippines and Malaysia, found in large numbers and extraordinary diversity on Borneo and Sumatra. The Malay name for the plants is “Periuk kera”, meaning monkey cup, referring to the plant being used by monkeys as a cup for drinking. These relatively big, amazing plants live and grow by preying: they trap, kill and feed on helpless insects.
Natural Habitat
Although widespread, pitcher plants are rather rare. They grow in sunlit, temperate and wet areas, where soil nutrients are very limited, but these are exactly the grounds favored by these insects-eaters. The nutrients they strive on are nitrogen, phosphorus, potassium and iron, which they get from the prey they consume.
Types of Pitcher Plants
On account of their habitat, pitcher plants belong to two large families:
- Species that live high above trees and fold the end of their leaves like a cup; they produce nectar in order to lure victims.
- Species that grow on the ground and benefit from a more generous source of food; they form a pitcher arising from the terminal portion of the leaf. Trap Types of Pitcher Plants
They can be categorized into two groups according to the traps they feature as well: the ones with active traps and those with passive traps. Trap types are modifications of a similar basic mechanism used for trapping, the hairy leaves that have evolved by natural selection.
The most usual passive trap is the “pitfall” trap. The name comes from the vase shape of the leaf. Living in areas of heavy rain, natural selection endowed pitcher plants with a system of defense against huge amounts of water, making it possible for the margins of the leaf to seal together. The waxy, slippery wall of the plant cup has downward pointing hairs which do not allow insects that fall in to crawl out. Attracted by the nectar secreted by the plant, the insects will slip and drown into the pool of digestive juices.
Another type of passive trap is the “flypaper” or adhesive trap. The leaves of the plant are covered in glands that secrete a sticky glue-like substance which entangles the victim.
Bladder traps one of the fastest and most precise passive traps. They have a small opening and a cover of tissue which forms the door. It opens inward and cannot be forced open. Around the door there are long trigger hairs. When organisms touch these hairs, the door opens and the victims are sucked inside where they are digested by enzymes.
Active traps also involve very fast movement. The best-known are the Venus flytrap and the waterwheel plant. The trap consists of two-lobed leaves and three trigger hairs sensitive to touch. For the lobes to close, one hair needs to be touched twice or two hairs must be touched one after another. They flip from convex to concave and entangle the prey. The process takes less than a second.
Another interesting fact about pitcher plants is that some insects, spiders and small frogs use them to live in or hide under their lid.
