Resource: Carnivorous Plants of Cartwheel Bay

Carnivorous plants capture and digest unsuspecting insects, and then absorb their nutrients for energy. They grow on every continent except Antarctica. In the United States, carnivorous plants can be found in every state, although some species are rare or endangered, and some are specific to certain regions. Many carnivorous plants grow well in the semi-tropical climate of the Southeastern United States. In South Carolina, an abundance of sunlight and water in the boggy, acidic soil of Cartwheel Bay create the perfect environment for many carnivorous plants, including pitcher plants, Venus flytraps, butterwort, and sundew, among others.

Cartwheel Bay is a Carolina bay, one of several elliptical depressions dotting the coasts of North and South Carolina. Some of the bays are permanent lakes and some are dry savannahs. Theories abound as to the origin of the bays, all curiously symmetrical and facing the same direction. Bogs such as those found in Cartwheel Bay are normally low in the nutrients nitrogen and phosphorous, both of which are necessary for photosynthesis. Insect-rich diets remediate this deficiency by providing plants with trace elements, in addition to potassium, calcium, magnesium, iron, and protein. Carnivorous plants do best in nutrient-deficient environments where resulting stress limits competition from other plants.

Because all carnivorous plants are flowering plants, it is estimated that they evolved between 65 and 125 million years ago along with other flowering plants, in-line with the co-evolution of pollinating insects. The “pitfall traps” in pitcher plants are commonly believed to have evolved from hairy, rolled leaves. Even among non-carnivorous plants, stalked glandular leaves with “hairs” are able to trap rainwater, which, in-turn, traps insects under the surface tension of the water. Bacteria grow quickly in these wet conditions, helping to speed the decay process and the release of insect nutrients to the plant. Some carnivorous plants subsequently developed the ability to produce sticky mucilage to help retain the insects, digestive enzymes to help break down their carcasses, and sweet-smelling pheromones to lure the unlucky bugs.

It is thought that the more aggressive and rapid-motion “snap traps”, like the Venus flytrap, evolved from something like the otherwise passive sundew, a “flypaper trap" that relies on sticky hairs to capture its prey. The evidence for this can be seen in the Venus flytrap’s teeth and trigger hairs, understood to be vestigial glue glands that became unnecessary with the development of the plant’s predatory capabilities. The movement of the Venus flytrap is made possible through the expansion and contraction of cells when shifting water content.

Unfortunately, habitats of carnivorous plants are quickly dwindling. In the United States alone, 95% of these plants’ native environments have been destroyed as a result of residential or commercial development. Even more damage is caused by pollution, the harvesting of plants for ornamental purposes and their poaching for illegal sale. Wetlands habitats are now being protected through the efforts of conservation organizations that educate people about threatened and endangered plants.

To learn about the importance of wetlands, check out The Value of Wetlands.

To see examples of other wetlands, check out An Everglades Visit and Hurricane Katrina: Wetland Destruction.

To learn more about carnivorous plants, see Carnivorous Plants.

To learn about the role of nitrogen, check out Decomposers and The Nitrogen Cycle.

• Describe some characteristics of a pitcher plant that enable it to use insects and other animal life as a source of energy.
• What are the characteristics of the Cartwheel Bay habitat that benefit carnivorous plants?
• Do you think it's accurate to refer to pitcher plants or Venus Fly Traps as carnivores?
• Where would you expect to find carnivorous plants in your local environment? Do you think the carnivorous plants have a competitive advantage in this setting?