Introduction                                  Back to Contents
 

The basic requirements for all green plants include carbon dioxide found in the air, water, and some minerals, such as nitrogen, phosphorus, potassium, etc. that the plants usually obtain from soil. The plants use sunlight to combine these elements and produce energy which they need to grow and reproduce. Plants generally grow well in soils rich in these mineral nutrients.

There are places in the world, however, where the soil is poor and does not contain all the minerals the plants need to survive. In places like bogs and marshes, the plants have a hard time obtaining sufficient nutrients from the soil. It is in such mineral-poor environment on the earth that the plants which adopted a rather unusual lifestyle may be found.

In the course of evolution, some plants have developed a means of obtaining nutrition from small animals such as insects, spiders, and other creatures, in order to get around the problem of poor nutrition in the soil. The leaves of these plants have been cleverly modified into various types of traps which not only can capture animal prey but also digest them for food. These unusual plants which acquired meat-eating habit are known as "carnivorous plants". There are over 500 different species of carnivorous plants in the world. This is rather a small group of plants, though, considering that there are well over 200,000 species of flowering plants in the whole world.   

There are four different types of traps adopted by carnivorous plants: steel traps, flypaper or adhesive traps, suction traps, and pitfalls. The famous Venus flytrap uses a steel trap. In this trap, a clamshell-like leaf snaps from both sides with an amazing speed when an insect enters the trap. The leaf has sensitive hairs which trip the closing mechanism. The trapped insect is firmly pinched inside and digested. Besides the Venus flytrap, only one other aquatic species (waterwheel plant) shares this most amazing and most advanced method of capturing.

In a flypaper trap, the leaf surface is covered with numerous hairs each tipped with a drop of dew-like, sticky mucilage. An insect that lands on a leaf is immediately mired down with this sticky, glue-like substance. Both sundews and butterworts use flypaper traps to capture their animal prey. There are some 150 species of sundews and about 70 species of butterworts worldwide.

The suction trap is found in aquatic plants called bladderworts. The plants bear a large number of tiny, balloon-like sacs in the water. When a tiny aquatic animal approaches one of the sacs, the miniature door suddenly opens and the prey is instantly sucked into the sac along with the water, and is imprisoned inside. There are over 200 species of bladderworts in the world.

The simplest form of trap is the pitfall. The leaf has become a hollow tube, or a pitcher, which usually contains some water at the base. An insect is attracted to the pitcher by its brilliant colors and sweet nectar. The rim of the pitcher opening is made slippery, and the insect often falls into the pitcher and drowns. Twenty or so species of pitcher plants from North and South America, some 90 species of tropical pitcher plants mainly from the tropical Asia, and one species of Australian pitcher plant all use the pitfall trap to capture their prey.

In this book you will learn about each of these prey-trapping mechanisms in detail as you read along. We will be focusing mainly on representative species growing in the United States for the description of each trapping method.
 

Introduction  VenusFlytrap  Sundews  PitcherPlants  CobraPlant  Butterworts  Bladderworts