Discovery of a new line of carnivorous plants | Biology

The newly identified lineage of carnivorous plants is represented by the Western False Asphodel (western triantha), a species of flowering plant from North America; its trap is unique among carnivorous plants and, unexpectedly based on theory, by placing all of its prey capture sites next to its insect-pollinated flowers.

Western False Asphodel Flower (western triantha) at Cypress Provincial Park, British Columbia, Canada. Image credit: Danilo Lima.

“Carnivorous plants have fascinated people since the Victorian era because they upset the usual order of things: they are an animal-eating plant,” said Professor Sean Graham, researcher in the department of botany. and the University of British Columbia Botanical Garden.

“We are delighted to have identified one that grows right here in our own backyard on the West Coast. “

western triantha can be found in wetlands and peatlands from Alaska to California and inland to Montana.

In summer, it grows tall flowering stems covered with sticky hairs that trap small insects like midges and midges.

“What is particularly unique about this carnivorous plant is that it traps insects near its insect-pollinated flowers,” said Qianshi Lin, a doctoral student in the Department of Botany and Botanical Garden of the ‘University of British Columbia.

“At first glance, it looks like a conflict between carnivore and pollination because you don’t want to kill the bugs that help you reproduce. “

“However, the plant appears to be able to separate friends from food.”

“We believe this western triantha is able to do this because its glandular hairs are not very sticky and can only trap midges and other small insects, so the much larger and stronger bees and butterflies that act like its pollinators are not captured, ”said Professor Tom Givnish, a researcher in the Department of Botany at the University of Wisconsin-Madison.

In their study, the researchers found that western triantha acquires more than half of its nitrogen (N) by digesting these trapped insects, a welcome treat in its nutrient-poor habitat.

“We tested the hypothesis that western triantha is carnivorous by doing a field experiment with ¹⁵Insects labeled with nitrogen to demonstrate nutrient uptake, ”they said.

“We have demonstrated a significant transfer of N from prey to Triantha, with about 64% foliar nitrogen obtained from prey capture in previous years, comparable to the levels inferred for cooccurrent round-leaved sundew, a recognized carnivore. “

“The nitrogen obtained by carnivores is exported from the inflorescence and developing fruits and can eventually be transferred to the leaves of the next year.”

“The glandular hairs of flowering stems secrete phosphatase, as seen in all carnivorous plants which directly digest prey.”

This is the 12th known independent evolution of the carnivore in the plant kingdom.

This is the first time that the trait has been discovered in the order Alismatales, a group of largely aquatic flowering plants.

It is also only the fourth established case of a carnivore in monocots, one of the major groups of flowering plants.

Some other species of the Triantha kind also has sticky hairs which trap insects. The authors plan to study these species to see how widespread the carnivore might be in the genus.

“It seems likely that there are other members of this group who will turn out to be carnivorous,” Professor Givnish said.

“The fact that TrianthaIts carnivorous lifestyle has eluded attention for so long despite the plant’s abundance and growth near major cities suggests that more carnivorous plants are waiting to be discovered off the beaten track. “

The team’s article was published in the Proceedings of the National Academy of Sciences.

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Qianshi Lin et al. 2021. A new line of carnivorous plants (Triantha) with a unique sticky inflorescence trap. PNAS 118 (33): e2022724118; doi: 10.1073 / pnas.2022724118