Researchers discover common flower is actually a bug-eating carnivore

10 Aug 2021

Upper stem of Triantha seen through a scanning electron microscope. Image: Qianshi Lin

The typical white flowers and sticky stem of the Triantha plant, which is common in the US and Canada, hid its carnivorous nature.

The Venus flytrap may be the most well-known carnivorous plant but its mouth-like leaves aren’t the only way plants capture creatures. In fact, a plant growing all across the west coast of North America has until now hidden its nature by appearing like any other flower.

New research from the University of British Columbia and University of Wisconsin-Madison, set to be published in the journal PNAS, provides a fresh look at the Triantha plant.

The flower grows along the west coast of the US and Canada in typically nutrient-poor areas. This particular research took samples from Cypress Mountain in Vancouver.

Most carnivorous plants trap their prey using their leaves. The white flowers of the plant Triantha, a species of false asphodel, don’t serve this function. Its sticky stem is instead the way it captures its prey.

“Carnivorous plants have fascinated people since the Victorian era because they turn the usual order of things on its head: this is a plant eating animals,” said co-author Dr Sean Graham, a professor in botany at University of British Columbia.

“We’re thrilled to have identified one growing right here in our own backyard on the west coast.”

The first clue came from genetic research with the Triantha plant. The researchers found an odd commonality between this plant and other bug-eating flora in the form of a missing gene.

This led the researchers to investigate whether the Triantha plant was actually a hidden carnivore. By attaching fruit flies with a modified nitrogen isotope to the sticky stem of the plant, the researchers were able to track the uptake of the element.

When compared to other carnivorous and non-carnivorous flora, the Triantha showed significant uptake of nitrogen from its prey. Researchers also found the presence a phosphatase, a digestive enzyme used by other carnivorous plants to obtain phosphorous.

The flower of the Triantha plant is shown. The petals of the flower are white and there are yellow stamen behind the petals.

The Triantha flower. Image: Danilo Lima

“What’s particularly unique about this carnivorous plant is that it traps insects near its insect-pollinated flowers,” said lead author Dr Qianshi Lin, who was a PhD student at University of British Columbia at the time of the study.

“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.”

The researchers worked out that the stem isn’t actually sticky enough to capture these pollinators, however. Instead, its stem is designed to supplement its nutrients through small bugs such as midges.

The proximity of the Triantha plant to large urban areas on the west coast of North America highlights how little might be known about the wildlife that researchers see every day. The study concluded that “other cryptic carnivores may yet remain to be discovered”, providing a reason for botanists to interrogate the plants in their own back gardens.

Sam Cox was a journalist at Silicon Republic covering sci-tech news