The swampy pine savanna within a 90-mile radius of Wilmington, North Carolina, is the one place on the planet where Venus flytraps are native. It is also home to a number of other species of carnivorous plants, less famous and more widespread but no less bizarre. You can find pitcher plants with leaves like champagne flutes, into which insects (and sometimes larger animals) lose themselves and die. Sundews envelop their victims in an embrace of sticky tentacles. In ponds and streams grow bladderworts, which slurp up their prey like underwater vacuum cleaners.
There is something wonderfully unsettling about a plant that feasts on animals. Perhaps it is the way it shatters all expectation. Carl Linnaeus, the great 18th-century Swedish naturalist who devised our system for ordering life, rebelled at the idea. For Venus flytraps to actually eat insects, he declared, would go "against the order of nature as willed by God." The plants only catch insects by accident, he reasoned, and once a hapless bug stopped struggling, the plant would surely open its leaves and let it go free.
Charles Darwin knew better, and the topsy-turvy ways of carnivorous plants enthralled him. In 1860, soon after he encountered his first carnivorous plant—the sundew Drosera—on an English heath, the author of Origin of Species wrote, "I care more about Drosera than the origin of all the species in the world." He spent months running experiments on the plants. He dropped flies on their leaves and watched them slowly fold their sticky tentacles over their prey. He excited them with bits of raw meat and egg yolk. He marveled how the weight of just a human hair was enough to initiate a response. "It appears to me that hardly any more remarkable fact than this has been observed in the vegetable kingdom," he wrote. Yet sundews ignored water drops, even those falling from a great height. To react to the false alarm of a rain shower, he reasoned, would obviously be a "great evil" to the plant. This was no accident. This was adaptation.
Darwin expanded his studies from sundews to other species, eventually recording his observations and experiments in 1875 in a book, Insectivorous Plants. He marveled at the exquisite quickness and power of the Venus flytrap, a plant he called "one of the most wonderful in the world." He showed that when a leaf snapped shut, it formed itself into "a temporary cup or stomach," secreting enzymes that could dissolve the prey. He noted that a leaf took more than a week to reopen after closing and reasoned that the interlocking spines along the margin of the leaf allowed undersized insects to escape, saving the plant the expense of digesting an insufficient meal. Darwin likened the hair-trigger speed of the Venus trap's movement—it snaps shut in about a tenth of a second—to the muscle contraction of animals. But plants don't have muscles and nerves. So how could they react like animals?