Carnivorous plant confirms Darwin's theory

A small alpine plant with delicate white and yellow flowers, the Saxifraga candelabrum, has been confirmed as carnivorous, validating a hypothesis put forth by Charles Darwin over 150 years ago. A new study published in Nature Communications reveals that this plant belongs to a previously unrecognized carnivorous lineage, capable of luring, capturing, and digesting insects to absorb vital nitrogen.

While many plants exhibit traits for capturing prey, formal classification as carnivorous requires adaptations for attraction, trapping, digestion, and nutrient absorption. Darwin speculated in 1875 that some Saxifraga species might be carnivorous due to sticky glandular hairs on their stems that trap insects, but conclusive evidence was lacking until now.

A research team, led by the Chinese Academy of Sciences, investigated S. candelabrum specimens from the Qinghai-Tibet Plateau and Hengduan Mountains. Field observations and sample analyses showed insects trapped on the glandular hairs of most studied plants, with mature specimens averaging 71 trapped insects. The presence of phosphatase, a digestive enzyme common in carnivorous plants, suggests S. candelabrum can digest its prey.

Further experiments involved feeding the plants marked Drosophila flies to test nutrient absorption. The study observed a significant increase in marked nitrogen levels in S. candelabrum and a control carnivorous species, unlike non-carnivorous controls. Genetic analysis also revealed similarities with other independently evolved carnivorous plants, including genes related to prey attraction, digestion, and nutrient uptake. The findings provide definitive proof of carnivory in Saxifraga, answering Darwin's long-standing hypothesis and indicating that this trait may be more prevalent among angiosperms than previously thought.