by Whit Gibbons

January 8, 2006

One of my former botany teachers, Joab Thomas, once told me that my columns on ecology had too few plant examples compared to animals. My rationale is that people are more interested in animals than in plants, primarily because animals are action figures, whereas plants just sit there. Plants are mostly inert, unless the wind is blowing. Nonetheless, Thomas is an excellent botanist whose advice is worth listening to. Some exciting plants do exist in nature, and providing a few examples will not be a bad thing.

Viewers of TV nature shows are captivated by carnivores. Lions, pythons, and sharks get more than their fair share of attention. But accounts of animals eating animals fall into the “dog bites man” category. For a twist of the “man bites dog” variety, we need to look at stories of plants eating animals. And indeed millions of animals are eaten alive by plants every year.

Animal-eating plants used to be called insectivorous plants because insects make up the bulk of their diet. But botanists now refer to them as carnivorous plants because animals besides insects are on the menu, including small birds, frogs, and mammals. Plants that capture and digest animals occur in many parts of the world, and several kinds can be found in North America. Pitcher plants, in which insects fall into a highly effective pitfall trap, are among the best known. In some, the column, or “pitcher,” is only a few inches high, but it can be almost three feet tall in the yellow trumpet pitcher plants. With downward-pointing hairs around the lip of the column and digestive liquor at the bottom of the flask, pitcher plants mean certain death for many insects. The bug that makes a misstep over the edge of the tube will soon become part of the plant world, as it is digested and absorbed.

The most spectacular pitcher plants are from Mt. Kinabalu National Park in Borneo, a region with the greatest concentration of pitcher plant species in the world. One of these, the rajah pitcher plant, has tubular flasks large enough to capture rats. These carnivorous plants hold more than a quart of digestive fluid. Unfortunately, poaching of these awesome giant pitcher plants has been a problem, and few remain in the wild compared to their abundance only a few decades ago.

Another unusual group of plants produce their own heat internally, a trait usually reserved for birds, mammals, and a few other animals. Perhaps the best known U.S. plant with heat producing properties is the eastern skunk cabbage. In the Northeast, skunk cabbages are among the earliest plants emerging in the spring, often pushing directly up through a covering of snow that is melted by their generated heat. Some skunk cabbages have been reported to raise their temperature 45 degrees higher than their environment.

Another heat-producing plant is the voodoo lily, a tropical species of Southeast Asia. With a beauty typical of other lilies, the voodoo lily has a striking purple flower and reaches a height of almost three feet. Despite their ornamental appearance, voodoo lilies have a trait that might diminish their popularity in the garden. During the period of pollination, the flowers heat up, with temperatures inside a flower in the cool shade sometimes reaching temperatures of 110°F. At this time, they smell like rotting meat.

One trait we are often interested in with regard to animals is their size. How long is an anaconda? How high can a grizzly bear stand? How much does the bass you caught weigh? What about plants--what is the biggest flower in the world? The answer: Rafflesia. Found in Indonesian rainforests this plant truly qualifies as bizarre, because all you see is flower. It has no leaves, no limbs, no roots. In fact, Rafflesia does not even have chlorophyll. It is just a giant, eye-catching flower that can be more than three feet in diameter and weigh more than 40 pounds. It has parasitic filaments that feed off the roots of a particular species of vine.

None of these plants would make good Discovery Channel action videos, but all serve as superb examples of the diversity of life and the many secrets and mysteries that await our understanding.

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