Secretly Carnivorous Plant Has Been Hiding in Plain Sight, Say Scientists

The first carnivorous plant in twenty years has been discovered by researchers—and as it turns out, its unique abilities have been hiding in plain sight all along.

According to a study published in Proceedings of the National Academy of Sciences (PNAS), Triantha occidentalis, a common, flowering plant found along the Pacific coast from Canada to California, has actually evolved to gain nutrients via a carnivorous diet.

Until now, scientists have only recognized eleven distinct lineages of carnivorous plants, each with its own origin. This North American flower, however, represents a twelfth, new lineage that evolved independently from any other.

The habitats preferred by carnivorous plants "usually involve wet, low-nutrient sites including bogs, swamps, water bodies, watercourses, forests and sandy or rocky sites," according to the London Natural History Museum. Because these types of areas have fewer nutrients available in their soils, the plant species evolved to eat animals to supplement their nutritional needs.

Carnivorous Plant Stem
Triantha occidentalis is able to trap prey using a sticky surface. Above is a field specimen from North Cascades National Park, Washington, with insects trapped on the plant's sticky stem. Qianshi Lin

The museum also noted that "there are currently around 630 species of carnivorous plant known to science" and that they "can be found on every continent except Antarctica."

Botanist Sean Graham and his team first suspected that Triantha occidentalis might be carnivorous, according to a press release, after realizing that it lacked a specific gene that many carnivorous plant species also have missing.

The species, which lives in nutrient-poor wetlands and bogs, is also notable for trapping insects with sticky glandular hairs across its stem,another possible indication of carnivory.

The following research and its analysis was "a real collaboration," study co-author and professor of botany Thomas J. Givnish told Newsweek.

In order to test the hypothesis, graduate student Qianshi Lin designed an experiment in which dead fruit flies, having been given a nitrogen isotope, were stuck to the stem of a Triantha occidentalis. The team then measured the levels of nitrogen absorbed by the plant specimen, ultimately concluding that it "acquired up to 64 [percent] of its nitrogen from insects, similar to known carnivorous plants and far above the level absorbed incidentally by non-carnivorous plants."

Especially interesting is the species' innate ability to distinguish between insects that are ideal for food, versus those that work as helpful pollinators. "What's particularly unique about this carnivorous plant is that it traps insects near its insect-pollinated flowers," Lin explained in the press release. "On the surface, this seems like a conflict between carnivory and pollination because you don't want to kill the insects that are helping you reproduce."

Triantha occidentalis, however, avoids this issue by remaining only slightly sticky—meaning that, while the plant can trap tiny insects like midges, it's not sticky enough to disturb the work of pollinators like bees and butterflies.

In order to actually digest the insects it catches, the plant's stem secretes a phosphatase, "a kind of digestive enzyme that breaks down the prey immobilized by the viscid secretions of the hairs," Givnish explained. At that point, "the digest is then resorbed through those hairs."

Now, further work is required in order to determine if other secretly carnivorous plants are also out there. "There are many plants with sticky glandular hairs, of course, and in almost all cases, it appears that those hairs are defensive in nature and the plants do not benefit from absorbing nutrients from the plant-eating insects they've entrapped," Givnish said. "But such defensive hairs might provide a critical first step toward carnivory, as Darwin argued long ago, and as my colleagues and I have supported based on analyses of relationships among carnivores and non-carnivores."

He added: "There might easily be several carnivorous plants to be discovered with such sticky hairs."

Carnivorous Plant
The Triantha occidentalis is one of 630 carnivorous plants known to science. Shown above is a flowering Triantha occidentalis plant. Danilo Lima

Update 8/11/2021 5:07 p.m. ET: This story has been updated with comments from the study's co-author, Thomas J. Givnish.