"The Little Shop of Horrors"

"The Little Shop of Horrors"

Scattered throughout the world are more than 500 species of plants that subsist partly on the breakdown of animal tissue. Such flora are designated as carnivorous or insectivorous plants since their most common prey is flying insects. They are usually found living in marshy places where little or no nitrogen can be obtained. The plants must obtain this necessary nutrient from the insects they eat. The major portion of their food, however, is provided through the process of photosynthesis, as is true for most of the earth's plant life.

Since plants are sedentary, they must develop a way to trap insects to obtain life—sustaining nitrogen. The various species have evolved ingenious methods for attracting and holding prey. Some carnivorous plants have colored flowers that are scented in such a way that, at a distance, they appear and smell like decaying meat. This certainly attracts insects for dinner. Most of the plants contain glands that give off a digestive fluid, helping them assimilate their food. Nature has produced a number of remarkable species of carnivorous plants. One of the most extraordinary is also one of the best know, the Venus's—flytrap, Dionaea.

The Venus's—flytrap has evolved an almost perfect trapping mechanism. At the end of the plant's leaves are flaps that resemble an open bear trap. On each flap are three extremely sensitive trigger hairs. If an insect touches a hair only once, nothing happens, but if it touches two hairs or the same hair twice, the flaps spring closed and the sharp bordering spines interlock to imprison the victim. This closing motion is extremely rapid; scientists have timed some closing actions at less than half a second! The plant then secretes digestive fluid that dissolves the edible part of the trapped insect. In a few days the flaps will open again and reveal only the rejected carcass of the victim, which is soon blown away by wind.

This trap is so foolproof that, since two hairs must be touched or one hair touched twice, a windblown particle or a drop of rain landing on the open flap will not spring the trap!

Another carnivorous plant, also quite remarkable in its adaptation for catching prey, is the famous pitcher plant Nepenthes. It grows abundantly in the Malaysian forests and is related to a species common in bogs of the eastern United States. It is similar to the Venus's—flytrap in that the ends of its leaves have also evolved into an almost perfect trap. These leaves are shaped like large pitchers that are partially filled with water. The plant is brightly colored and gives off a peculiar odor. Both features serve to lure insects, which alight on the waxy lip of the pitcher. Because the lip is extremely slippery, the insect slides on it and falls into the water. Numerous downward—pointing hairs prevent the insect from climbing out. Eventually it is drowned and slowly digested with the help of a weak enzyme secreted by the leaf.

A most remarkably abundant carnivorous plant is the genus Drosera, more commonly known as the sundew. It is a relatively small plant with six— to eight—inch stems growing upward. Its leaves, about the diameter of a small coin, grow in clusters near the base of the stem. These leaves contain droplets of a sticky fluid produced by special glands. When sunlight shines on the fluid, it glistens like drops of dew, giving that plant its name.

It is this sparkling of light on the leaves that attracts the prey, usually a small fly. The leaves contain the necessary ensnaring equipment, in this case about 400 small, flexible hairlike bristles that are progressively larger toward the edge of the leaf.

When an insect alights on the leaf, the alluring fluid becomes the first snare, smearing and smothering the insect. The insect's struggles serve only to stimulate more secretion, and within minutes the inner hairs bend inward, gradually pinning down the captured prey. Very soon, after the outer hairs begin to curl inward, the insect becomes hopelessly engulfed in a web of sticky hairs. The edges of the leaf then curl inward and completely enfold the victim, which is by now past all signs of life. The glands then produce the juices that digest the insect.

Usually a week passes before the plant is satisfied and its meal is completely absorbed. It will then gradually unfold and reset the trap. The plant will once again patiently wait for its next victim to be attracted by the fluids on its leaves that glitter in the sunlight like drops of morning dew.

No discussion of carnivorous plants is complete without considering the subject of man—eating trees or plants. In fact, with the release of the stage hit The Little Shop of Horrors, interest in and speculation about man—eating plants have been renewed.

From time to time travelers to the island of Madagascar have returned claiming that a man—eating tree exists there. Strangely, though, whenever an investigation is undertaken the tree is always unfortunately on another part of the island. In 1920 American Weekly published an apparent eyewitness account, with a memorable artist's rendering, of the sacrifice of a maiden to a carnivorous tree. Since the story, in a popular newspaper supplement, was widely accepted as authentic, the legend refuses to die. The truth about man—eating trees or plants is that they are not now, and probably never have been, in existence!

From the book: 
Our Fascinating Earth