Several of us here on the Herbaria 3.0 team have had passionate interest in carnivorous plants and the people who study them. Maura Flannery’s post “What’s in a Name?” tells us about the carnivorous Darlingtonia californica. Tina Gianquitto and Dawn Sanders have both obsessed over Mary Treat, a popular 19th-century naturalist who studied the plants in New Jersey and Florida.
“I should very much like to hear about one point…”
Insectivorous plants were Mary Treat’s speciality. In fact, her skills as a “good observer,” as the famous botanist Asa Gray called her, were so well-known that Charles Darwin asked her to perform specific experiments on insectivorous plants. “I should very much like to hear about one point” about Dionaea‘s ability to catch more than one insect successively, he wrote to Treat in 1874. She responded by recording the dietary habits of more than twenty five plants over a period of weeks. Darwin then incorporated her observations into Insectivorous Plants (1875), a book that remains a definitive treatment of the subject. [Visit the Darwin Correspondence Project to see the more letters between Darwin and Treat.]
Treat’s observations helped Darwin establish the fact that carnivorous plants not only lure, trap, and kill insects, but that the plants also digest the organisms with enzymes analogous to pepsin. Darwin was able to puzzle out that insectivorous plants, which typically inhabit boggy, nutrient (nitrogen) poor soils, are able to turn leaves into roots, drawing precious nitrogen from the insect bodies they ingest!
“…I was as good to eat as a bug!”
Here is how Mary Treat describes sacrificing a finger to a Venus fly trap:
“If I forced open a leaf in two or three days after an insect was caught, I found it enveloped in a copious slimy secretion; but when the leaf was ready to open of itself, had digested its victim, all this secretion had disappeared–no doubt gone through the circulation to the bulbous-like root, to help nourish and enable it to through up other leaf-traps.”
“That I might more fully test the strength and power of the plant, I one day placed the tip of my little finger in a trap, resolving to become a self-made prisoner for five hours at least. I took an easy chair, and let my arm rest upon the table and my hand upon the edge of the pot, and with plenty of reading matter before me, what should hinder me from keeping my resolve? In less than fifteen minutes I was surprised at the amount of pressure about my finger, and for more than an hour the pressure seemed slightly to increase, but by this time my arm began to pain me. Here was a problem for the psychologist. Was it the knowledge of my being held fast that caused the pain? Surely I have kept quiet longer than this without any discomfort! In less than two hours I was obliged to take my finger from the plant, defeated in so simple an experiment, and heartily ashamed that I could not better control my nerves. The slimy secretion had commenced oozing slightly from the inner surface of the trap, and if I could have kept the position for five hours, I presume it would have been much more copious, the plant not knowing but that I was as good to eat as a bug!”
Mary Treat’s experiments with carnivorous plants captivated readers of her best-selling book, Home Studies in Nature. Other authors have found both her and her subjects equally fascinating. Barbara Kingsolver recently published Unsheltered, a novel based on Treat’s life. And just because I can’t resist, check out this incredible time-lapse video of insect-eating plants in action, Carnivora Gardinum, from filmmaker Chris Fields.
Author: Tina Gianquitto