Sundews prove that the adage, “You are what you eat,” doesn’t always apply.
These plants do the unexpected: They eat animals. No vegetarianism here, and photosynthesis only goes so far with them. Sundews are carnivorous plants and will devour insects for sustenance and survival.
Living in nutrient-poor bogs and on the edges of ponds and wet meadows, sundews need to supplement their diet. Their roots bring in nutrients, but not enough, so they consume insects for a protein-rich snack.
Spiders, mites and other insects are a necessary part of the sundew’s diet. Because sundews can’t move, they have developed an ingenious method of attracting, capturing and consuming their mobile prey.
It is known as semi-active seizure. To understand it, one must know a bit about the characteristics and mechanics of these green gourmands. Sundew leaves have many hairs, or tentacles, tipped with sticky fluid that attracts insects with its glistening appeal — the “sundew” of the plant’s name.
Creepy crawlers touch the dew and get stuck in the adhesive fluid. Fighting to get free only makes things worse for the insect as it becomes covered with the lethal liquid. The plant’s other tentacles move to enclose the fighting insect. This ability of plants to respond to touch and vibrations by moving is called thigmonasty. The presence of a meal in a sundew’s clutches will trigger the release of another enzyme that digests the trapped prey.
And it isn’t only a few insects that fall victim to the sundew. In one study of a two-acre bog of sundews, scientists estimated that about six million insects were trapped by this ferocious flora. But that is not the only reason to be impressed by these predatory plants.
It is not just deadly deeds for which the sundew is known.
American teacher, lawyer, merchant and botanist Manasseh Cutler wrote a treatise on New England botany in 1785 and of the sundew observed: “The whole plant is sufficiently acrimonious to erode the skin. But Dr. Withering says some ladies know how to mix the juice with milk, so as to make it an innocent and safe application to remove freckles and sunburn. The juice will destroy warts and corns. If the juice is put into a strainer, through which the warm milk from the cow is poured, and the milk set by for a day of two to become acescent (solid), it acquired a consistency and tenacity – neither the whey nor the cream will separate. In this state it is used by the inhabitants in the north of Sweden, and called an extremely grateful food.”
In addition to sundew, this plant goes by other names, including bed-rot, lustwort, moonwort and eyebright. The reasons for these aliases are obscure. British plantsman John Gerard, author of Gerard’s Herbal or General History of Plants, noted that sundew was called “in low Dutch, Loopichecruit, which in English signifieth Lustwart, because sheepe and other catell, if they do but onely taste of it, are provoked to lust.”
Other herbalists insisted that sundews endowed those that drank it with longevity and youthfulness, reporting that “In America it has been advocated as a cure for old age.” Charles Darwin liked sundews so much that he spent 285 pages on describing experiments with this and other carnivorous plants!
It isn’t necessary in this forum to follow Darwin’s example and write an extended treatise on this potent plant. However, in the matter of munching, this plant turns the tables on insects and thus provides us with some pretty interesting food for thought.
Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown.