Aug 4 (Reuters) – For most insects, a flowering alpine plant might seem an unlikely predator. But researchers have discovered that a delicate wildflower that grows in rocky mountain crevices in southwestern China lures prey onto sticky hairs, digests their bodies and absorbs the nutrients left behind. It \u200cis the first confirmed carnivorous plant in its botanical grouping.<\/p>\n
Its scientific name is Saxifraga candelabrum, and it is a member of a diverse botanical order \u2014 a \u200ctaxonomic category \u2014 called Saxifragales that spans more than 2,000 species.<\/p>\n
The plant grows on nutrient-poor rock faces in the Qinghai-Tibet Plateau and Hengduan Mountains of China, ranging from central and northern Yunnan Province to southwestern Sichuan Province \u200bat elevations of 2,500 to 3,300 metres (8,200 to 10,800 feet). It is covered with sticky reddish glandular hairs that trap small insects.<\/p>\n
Carnivorous plants are best known from swamps and wetlands, where species such as Venus flytraps, pitcher plants and sundews supplement scarce nutrients by catching prey. To qualify as truly carnivorous, a plant must do more than accidentally catch insects. It must absorb nutrients from captured animals and have specialised adaptations that help it attract, trap, digest and consume prey.<\/p>\n
In 1875, naturalist Charles Darwin suggested that two European Saxifraga species might be carnivorous after \u200cnoticing their sticky hairs and occasional bug victims, but never \u2060managed to prove it experimentally.<\/p>\n
The newly studied plant is a different species from the pair that Darwin examined, though closely related, but it shares the same insect-trapping structures that inspired his hypothesis.<\/p>\n
"We ran multiple tests on this plant and finally confirmed it is a real insect-eating \u2060plant. This proves Darwin's guess was correct, and shows how sharp his scientific judgment was," said Hang Sun, a research professor at the Chinese Academy of Sciences' Kunming Institute of Botany and one of the leaders of the study published in the journal Nature Communications.<\/p>\n
To determine whether it was actually feeding on insects, researchers used fruit flies raised on food enriched with a stable form \u200bof \u200bnitrogen.<\/p>\n
"Nitrogen is essential for plant growth. Most carnivorous plants live in nitrogen-poor habitats and obtain nitrogen by \u200bcapturing and digesting insects," Sun said.<\/p>\n
After placing the flies onto the \u200csticky hairs, they tracked the movement of the nitrogen through the plant.<\/p>\n
The nitrogen they tracked "is ultimately taken into the plant and found throughout the tissues of that plant. That would not happen unless there is uptake or movement into the plant," said botanist and study co-author Douglas Soltis of the University of Florida and the Florida Museum of Natural History.<\/p>\n
The captured nutrients did not end up distributed evenly throughout the plant. Instead, the highest levels of prey-derived nitrogen were found in the flowers of Saxifraga candelabrum, a species that reproduces only once during its lifetime.<\/p>\n
"Probably needs them for reproductive output. Flowers and seeds. Reproduction is key to survival," Soltis said.<\/p>\n
The researchers also found evidence that the plant actively \u200cattracts prey. Field experiments suggested that scent plays an important role in drawing insects to its \u200bflowers, while tests detected digestive enzyme activity in the glandular hairs, providing further evidence that the plant can \u200bbreak down captured insects.<\/p>\n
Catching insects comes with a potential drawback. Many carnivorous plants \u200bdepend on insects for pollination and risk trapping the very visitors needed for reproduction.<\/p>\n