Over 150 years since Charles Darwin postulated that certain sticky-leaved Saxifraga species might exhibit carnivorous behavior, researchers from the Kunming Institute of Botany, led by Tao Deng, have finally confirmed this phenomenon. However, their findings come from a close relative of the species that Darwin studied, located in the rocky crevices of southwestern China’s mountains.
Carnivorous plants are fascinating organisms that acquire nutrients, primarily nitrogen, through the attraction, capture, and digestion of small animals.
The independent evolution of carnivory under various physiological and ecological conditions has intrigued biologists for decades.
Carnivory has been documented in numerous flowering plants, spanning across 14 families.
These remarkable plants are classified into five major categories based on their trapping mechanisms, including pitfall traps in pitcher plants, snap traps in Venus flytraps, sticky traps in sundews, suction traps in bladderworts, and lobster-trap mechanisms in corkscrew plants.
In his 1875 publication Insectivorous Plants, Charles Darwin speculated that two European Saxifraga species could potentially trap and utilize insects due to their sticky, hair-laden leaves.
Unfortunately, Darwin’s feeding experiments were inconclusive, leading to the hypothesis being postponed for over a century.
“Inspired by his studies on carnivorous Drosera, Darwin suggested that two Saxifraga species — Saxifraga rotundifolia and Saxifraga umbrosa — might exhibit similar carnivorous traits,” explained Dr. Deng and his co-authors.
“Darwin considered these species among the most captivating cases of plants possessing glandular hairs.”
“Though Darwin attempted to validate his hypothesis through feeding trials, the initial tests lacked conclusive evidence.”
“This uncertainty hindered researchers from classifying these Saxifraga species as true carnivorous plants.”
Multiple lines of evidence for carnivory in Saxifraga candelabrum. Image credit: Zhang et al., doi: 10.1038/s41467-026-75288-y.
In their study, the researchers focused on another Saxifraga species — Saxifraga candelabrum, a small perennial herb thriving on nutrient-deficient cliffs of the Qinghai-Tibet Plateau and Hengduan Mountains.
Field surveys and analysis of 45 herbarium specimens collected between 1888 and 2016 revealed a significant number of trapped insects — primarily non-biting midges — present on the plant’s glandular hairs, suggesting that this behavior is widespread rather than incidental.
Experiments covering the plants with odor-blocking glass enclosures or sight-blocking mesh indicated that the plant attracts insects partly through scent. Chemical analyses of its floral volatiles unveiled compounds known to attract insects in various plants.
Chemical tests employing a fluorescent marker demonstrated that Saxifraga candelabrum produces phosphatase, a digestive enzyme also found in other carnivorous species, while a related non-carnivorous Saxifraga species showed none of this activity.
Most notably, researchers enriched fruit flies with a heavy nitrogen isotope, nitrogen-15 (15N), and placed them on the plants. Nitrogen from these insects was later found in the tissues of Saxifraga candelabrum — particularly its flowers — while two non-carnivorous control plants exhibited no such uptake.
This finding confirms that nitrogen is directly absorbed from prey, rather than incidentally collected from decaying insects in the soil.
Interestingly, the plant seems to favor trapping smaller, non-pollinating insects over the larger flies that serve as its pollinators.
The scientists also sequenced Saxifraga candelabrum’s genome, comparing it to other carnivorous species that evolved trapping mechanisms independently, such as sundews and the South African shrub Roridula.
They identified shared patterns of gene expansion and accelerated evolution in genes related to prey attraction, digestion, and nutrient absorption.
“Our results offer conclusive evidence of carnivory in Saxifraga, confirming Darwin’s long-held hypothesis that some Saxifraga species possess carnivorous capabilities and indicating that carnivory could be more prevalent among angiosperms than previously thought,” the authors concluded.
The full research paper was published this week in the journal Nature Communications.
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XJ. Zhang et al., 2026. Identification of carnivory in the flowering plant Saxifraga via multidisciplinary evidence. Nat Commun 17, 7557; doi: 10.1038/s41467-026-75288-y
Source: www.sci.news
