A collaborative research team led by Tao Deng of the Chinese Academy of Sciences has provided definitive evidence that Saxifraga candelabrum, a delicate alpine plant native to high elevations in the Qinghai-Tibetan and Hengduan Mountains of China, is carnivorous. This discovery confirms a hypothesis first proposed by Charles Darwin in 1875, nearly 150 years ago, regarding the carnivorous nature of some species within the Saxifraga genus.

Carnivorous plants are distinguished by their ability to supplement nutrient intake by capturing and digesting small animals, primarily insects, an adaptation often seen in nutrient-poor environments. While the Venus flytrap is a well-known example, the full extent of carnivory across plant species remains a subject of scientific inquiry. Darwin had speculated that the sticky glandular hairs found on Saxifraga leaves served to trap insects, but until now, no conclusive evidence confirmed that the plant digestes its prey and derives nutrients from them.

The study, published recently in Nature Communications, involved detailed field observations and laboratory analyses. Researchers surveyed the plants growing in their natural alpine habitat and found insects stuck to the glandular hairs on 43 out of 45 specimens, with mature plants averaging 17 trapped insects each. To ascertain whether the plant digests these trapped insects, the team tested for the presence of phosphatase enzymes—common digestive enzymes in known carnivorous plants—and confirmed their activity in Saxifraga candelabrum.

Further evidence was obtained through feeding experiments using fruit flies (Drosophila) labeled with a stable nitrogen isotope. The researchers observed a significant increase in nitrogen levels within the plant following insect ingestion, indicating active digestion and nutrient absorption. Genomic analysis also revealed similarities between S. candelabrum and other carnivorous plants, suggesting evolutionary convergence or shared ancestry in carnivorous traits.

The findings extend the known diversity of carnivorous plants, which currently includes about 14 families employing five primary trapping mechanisms: snap traps (Venus flytraps), pitcher traps, adhesive traps (such as sundews and now Saxifraga), suction traps (bladderworts), and lobster-pot traps (corkscrew plants). The identification of Saxifraga candelabrum as carnivorous suggests that this adaptation may be more widespread in the plant kingdom than previously recognized.

The study also highlights the specialized ecological niches these plants occupy, often in nutrient-deficient alpine or bog environments where insect-derived nutrients provide a critical supplement to their diet. This work not only confirms a longstanding theoretical prediction by Darwin but also opens new avenues for research into plant evolution and adaptation to extreme habitats.