Charles Darwin was fascinated by plants that behaved in unexpectedly animal-like ways. In 1875, he proposed that some members of the Saxifraga genus might be carnivorous because their sticky hairs appeared capable of trapping insects.

His experiments, however, never produced enough evidence to prove the idea. Now, more than a century later, researchers have confirmed that at least one species really does capture, digest and absorb nutrients from insects.

A Mountain Plant With Sticky Traps

The species at the centre of the study is Saxifraga candelabrum, which grows at high elevations in China’s Hengduan Mountains. Mature plants were found with an average of 71 insects trapped on the sticky hairs covering their flowering branches. Younger plants, which had fewer branches, caught very few insects or none at all. This pattern suggested that the sticky glandular hairs were doing more than simply protecting the plant. Researchers then tested whether the plant actively attracted insects. Some flowering plants were enclosed in glass, which blocked odours, while others were covered with mesh, limiting visual signals. The experiments indicated that smell played an important role in attracting prey.

It Does Not Trap Everything

One of the most interesting findings was that the plant appeared to avoid catching its most useful visitors. Large insects capable of pollinating the flowers were rarely trapped, while smaller insects were caught much more often. Study co-author Hang Sun explained indirectly that the plant seems to target small prey while largely sparing larger pollinators. That balance is important: a carnivorous plant still needs pollination, so trapping every insect would create an obvious biological disadvantage.

Scientists Tested the Digestion

Capturing an insect is not enough to classify a plant as carnivorous. A true carnivorous plant must also digest the animal and absorb nutrients from it. Chemical analysis found that S. candelabrum produces phosphatase, an enzyme also used by other carnivorous plants to break down prey. Researchers then fed fruit flies a special nitrogen isotope before allowing the plants to trap them. Afterward, nitrogen levels increased inside S. candelabrum. The same increase did not occur in a control plant.

Genetics Added Another Clue

The team also examined the plant’s genes. Their analysis showed similarities with genes found in other known carnivorous plants. Sun noted that this genomic evidence independently strengthened the case that S. candelabrum should be considered truly carnivorous.

Darwin’s Idea May Go Further

Botanist Doug Soltis, one of the study’s co-authors, described the confirmation of Darwin’s prediction as especially significant. He also suggested that other species within the same plant family may eventually turn out to be carnivorous because many possess similar sticky hairs.

That idea remains a hypothesis and will require further testing. Botanists outside the study have also emphasized that discoveries like this show how much remains unknown about apparently familiar plants.