The Venus flytrap (Dionaea muscipula) is probably the best known of the more than 600 species of carnivorous plants, which absorb nutrients from prey rather than through their roots. The flytrap grows in the wild only in wet pine savannas of the U.S. Carolinas, a habitat slowly disappearing because of land development. Despite its name, the Venus flytrap catches more ants, beetles and other crawling things than flies.
The only species other than the Venus flytrap to actively trap its meal is the waterwheel (Aldrovanda vesiculosa). This European aquatic plant floats free on the water, rootless, consuming small crustaceans, insect larvae and snails. Its snapping behavior was first observed in 1861, but the plant’s carnivorous nature wasn’t proven until Charles Darwin studied the waterwheel more than a decade later.
Albany pitcher plant
Though the Albany pitcher plant (Cephalotus follicularis) was first described in 1806, Charles Darwin missed this plant when the HMS Beagle stopped by southwestern Australia in 1839. The plant can be found in peaty swamps where it lures insects—mostly ants—with its nectar glands into a one- to two-inch tall pitcher filled with digestive fluid.
Yellow pitcher plant
The yellow pitcher plant (Sarracenia flava) grows up to three feet tall and lives in wet pinelands and bogs in the southeastern United States. The plant’s nectar glands secrete a chemical soup that includes coniine, a narcotic that may intoxicate the plant’s prey. Waxy scales on the upper surfaces of the pitcher increase the likelihood that insects—preferably wasps, bees and flies—will fall in.
This tropical pitcher plant grows in the highlands of Sulawesi in Indonesia. There are at least 120 members of the Nepenthes genus growing throughout Southeast Asia, in parts of Australia and as far away as Madagascar. They mostly consume small insects and other arthropods but larger plants, such as N. rajah, have been found digesting rats.
Charles Darwin believed that the rainbow plant (Byblis gigantea), a native of southwestern Australia, was probably carnivorous, but modern scientists aren’t so sure. Sticky hairs on the plant snag insects, which get stuck and die. B. gigantea has enzymes capable of digesting the bugs, but it is not clear that the plant is doing so. Sundew bugs (Setocoris bybliphilus) suck out juices from the captured insects, and B. gigantea may benefit from those bugs’ waste products.
Though the king sundew (Drosera regia) grows only in one valley in South Africa, members of the Drosera genus can be found on all continents except Antarctica. Charles Darwin devoted much of his book Insectivorous Plants to the sundews. Sticky mucilage on Drosera plants traps prey—usually an insect attracted to light reflecting off drops of dew or to the plant’s reddish tentacles—and eventually suffocates it. Digestive enzymes then break down the plant’s meal.
Though members of the Pinguicula genus tend to be small, the summer rosettes of the Mexican butterwort (P. moranensis) grow up to about eight inches in diameter. The plant, which grows in Mexico, Guatemala and El Salvador, traps prey—usually gnats and flies but also pollen grains—on its leaves with sticky mucilage. The leaf surface then slightly sinks and the hollow fills with digestive enzymes. The meal is kept fresh with a bactericide that prevents rotting while digestion takes place.
Stinking passion flower
The stinking passion flower (Passiflora foetida) is native to wet tropical areas in the West Indies and central South America. The plant has modified leaves that can trap insects, but scientists have not yet determined if the stinking passion flower is capable of digesting such a meal.
A new study led by the Royal Botanic Gardens, Kew in England has suggested that plant carnivory may be “far more common than previously held because of many species being subtly carnivorous.” Scientists searching for carnivorous plants may want to look at the Solanaceae family, which includes the familiar petunia. A scientist in the early 20th century demonstrated that two species of petunia produce digestive enzymes, though he was unable to find evidence that the plants absorbed a meal. The leaves of the wild potato also secrete enzymes. And Charles Darwin showed in the late 19th century that the tobacco plant, another member of this family, is covered with hairs that catch insects.