Petal-closing species found on the Qinghai-Tibet Plateau. (Photo provided to China Daily)
Chinese scientists have discovered four species of Gentiana on the Qinghai-Tibet Plateau whose flowers can close within seconds of being touched, making them the most sensitive flowers in the world, according to a recently published study.
Netizens on Chinese social media have affectionately dubbed the flowers the "shiest" and "most humble" flora in the world. The rapid movement of petals has always been fascinating to scientists and nature lovers, as unlike animals, plants are generally perceived as static organisms.
Some specialized leaves of carnivorous plants can react to touch within a matter of seconds, such as the Venus flytrap. Prior to the Gentiana discoveries, the only other known flower to display such behavior was the sundew plant. The sundew can contract its crown within two to 10 minutes after stimulation, according to the study in China's English-language scientific journal, Science Bulletin.
However, the four Gentiana species take seven to 210 seconds to close their petals, making them the most sensitive and fast-reacting flowers in the world, the study said.
The flowers were discovered in 2020 near a lake in Nagchu, Tibet autonomous region. The discoveries were made during the ongoing second Tibetan Plateau Scientific Expedition and Research mission, which began in August 2017.
"It was startling to witness with the naked eye. The flowers disappeared momentarily in front of you," said Dai Can, a professor at Hubei University's School of Resources and Environmental Science, one of the scientists who led the study.
After visiting more than 20 sites, they found four species of Gentiana that exhibit such movements: G. pseudoaquatica; G. prostrata var. karelinii; G. clarkei, and an unidentified gentian species.
One explanation for the rapid-closure behavior is that it could be a defense mechanism for the flower to protect itself from repeated intrusions by bumblebees.
Due to the insect's large body size and tendency to slit open floral tubes to obtain nectar, 98.8 percent of the flowers the bumblebees visited displayed induced floral closure, the study said.
The damage caused to the flowers by bumblebees collecting nectar was substantial. Nearly 80 percent of flowers experienced exterior damage, with 6 percent showing injuries to the ovary. Therefore, the rapid-closure response may be useful in discouraging bumblebees and protecting the flower's ovary against fatal damage, the study said.
Another explanation could be that the plant has evolved to encourage bumblebees to transfer pollen more efficiently among a wider range of flowers, since a closed crown would signal to the insect that it has already been visited and the visitor should look for another candidate.
Wang Qingfeng, a researcher at the Chinese Academy of Sciences' Wuhan Botanical Garden, said both the induced defense and pollination stimulator theories are exciting and should be examined further in future studies.