Looking for carnivorous plants in WNC
Some plants like Jack-in-the-pulpit and Dutchman’s-pipe have evolved methods of entrapping insects in their flowers so as to assure pollination. But only a few plant species in North America actually devour insects so as to obtain life-giving sustenance. The carnivorous plants of North America that come to mind are the various pitcher plants, sundews, bladderworts, and butterworts, as well as the infamous Venus’ flytrap, known only from the coastal plain of the Carolinas.
In specialized habitats (primarily bogs) here in Western North Carolina, there are four pitcher plant species, five bladderwort species, and three sundew species. There are excellent photos of all of these insect-eaters in Justice and Bell’s Wild Flowers of North Carolina (1968).
Your chances of observing a carnivorous plant in action are by far the greatest with round-leaved sundew (Drosera rotundifolia), which has been reported in 11 WNC counties. Most sources correctly state that it is commonly found in sphagnum bogs. But locating and penetrating a bog can be hellish; so, you’ll be pleased to learn that they can also be found along high elevation rock outcrops, where sphagnum mats have formed in moist crevices.
They’re hard to spot until you get the hang of it, but if you do persevere and encounter round-leaved sundew, you’ll be in for a treat. From July into August, the little plant puts up an erect stalk about six to ten inches high that bears minute white flowers that remain open for only a few hours.
The most conspicuous and interesting aspect of the plant, however, is the basal rosette of rounded leaves that display numerous slender red hairs. These hairs (setae) have glands at their tips that produce droplets of sticky fluid, which glisten in the sunlight and attract gnats and other tiny insects.
Upon alighting on a sundew leaf, the insect immediately becomes stuck in the adhesive fluid. That’s when things get interesting. The surrounding hairs are stimulated by the thrashing of the victim and bend inward, ensnaring and encasing it. The plant then exudes digestive juices similar to those found in the stomachs of mammals. These enzymes break down the insect’s body so that it can be absorbed through the leaves.
Observing the habitat sundews and other carnivorous plants live in helps one understand why they evolved such a curious lifestyle. Bogs and granite outcrops are highly acidic environments where sources of nitrogen are scarce, if not non-existent. On the other hand, the bodies of insects are rich in protein, which, when digested, breaks down into compounds rich in nitrogen.
Somewhere along the line, a few bog and rock outcrop species “determined” that the best way to survive was to utilize the nitrogen in their pollinators. Pitcher plants “devised” insect-attracting hollow leaves that function as water traps. Venus’ flytrap “came up with” spectacular hinged leaves that engulf its guests in vise-like spiked leaves. Sundews “concocted” glandular hairs. And so on.
I have heard a few botanists theorize that Dutchman’s pipe and Jack-in-the-pulpit might be headed in the same direction. That is, now that they have mastered the art of capturing insects for pollination, how long can it be before they start feeding upon them as well? The glitch in that theory is the fact that those two plants don’t favor nitrogen-deficient habitats. Why bother?