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New carnivorous plant Triantha spares friendly pollinators

A new carnivorous plant has been discovered in western North America. A team of botanists at the University of Wisconsin-Madison and the University of British Columbia report that Triantha occidentalis can be found in wetlands from Alaska to California, and inland to Montana.

“What’s particularly unique about this carnivorous plant is that it traps insects near its insect-pollinated flowers,” said study lead author Qianshi Lin. “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.”

In the summertime, Triantha produces tall flowering stems covered with sticky hairs that trap small insects. The researchers determined that these insects provide the plants with more than half of the nitrogen they need. This makes an important contribution to their nutritional needs, as they live in a nutrient-poor habitat.

According to the study authors, Triantha represents the 12th known independent evolution of carnivory in the plant kingdom, and the first time the trait has been discovered in the Alismatales order, a group of largely aquatic flowering plants. The experts report that Triantha appears to be capable of sparing friendly pollinators.

“We believe that Triantha occidentalis is able to do this because its glandular hairs are not very sticky, and can only entrap midges and other small insects, so that the much larger and stronger bees and butterflies that act as its pollinators are not captured,” said study co-author Professor Tom Givnish.

Some other Triantha species, including Triantha glutinosa in Wisconsin, also have sticky hairs that trap insects. In the future, the researchers plan to study more species to see how widespread carnivory might be among the Triantha genus.

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

The study is published in the journal Proceedings of the National Academy of Sciences.

By Chrissy Sexton, Staff Writer

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