Fritillaria belongs to the genus of flowering spring bulbous perennial plants of the Liliaceae (lily) family. This genus has 130-140 species and 8 divisions of subgenera. Fritillaria delavayi, a small herb has a bulb of 2cm in diameter and often elongated. Its stem is 7cm tall or less with alternating leaves of greyish green. Its mainly found in Western China, Tibet, and Bhutan and grows on rocky alpine slopes. Its a commercially valuable plant in horticulture and the dried bulbs have been used in traditional Chinese medicine for over 2000 years in treating heart and lung illnesses.
The research was done by scientists from the Kunming Institute of Botany (Chinese Academy of Sciences) and the University of Exeter. F.delavayi of the Hengduan Mountains in Southwest China grows a short stem with three to five bright green leaves and a yellow-hued tulip-shaped flower. It is the only known Fritillaria species that grow at higher altitudes. This bright coloured flower and green leaves which are easy to spot have now started to grow grey and brown similar to the rocks they live on. Scientists believe the plant is evolving genetically for hiding from it’s predators – humans.
The researchers found the herb was expected to camouflage in the heavily harvested area . We are aware of animals camouflaging but not much of the plants. The study’s lead author, Dr Yang Niu has spent years recording cases of plants disguising themselves. For example, the mottling leaves of some plants in a forest which makes it harder for herbivores to spot them and Lithops (living stone plants) impersonating as pebbles. Another study done by Dr Niu on an alpine plant (Corydalis benecincta) is preyed on by caterpillars who nibble on the plant’s leaves. Plants that engage in camouflaging has been reported worldwide and they have enemies too. The discolouration of the F.delavayi has been baffling as no animals seemed to feed on it. This is because the herb produces chemicals which repel rodents which is ironic as this chemical compound found in the medicinal herb is what attracts humans.
F.delavayi‘s demand has been increasing steadily and the scarce supply has sparked a treasure hunt for these herbs. The value of one kilogram of plant’s bulb is estimated at around $480. The bulb is the size of a thumbnail and requires more than 3,500 individual plants for producing one kilogram of medicine.
To confirm the theory of camouflaging enacted by F.delavayi, the researchers checked with local herbalists who had six years of records that demonstrate where the plants were cultivated and how many were selected. They established the heavily harvested areas and ease of access to those hidden away in rocky, mountain terrains. The plant colour at different locations was measured using a spectrophotometer and correlated with the population of plants that have been dug up in a particular spot along with flower colour.
The plants were still bright yellow and green in hard to access regions, meanwhile the heavily harvested locations had a duller appearance. Researchers even built a game called “Spot the Plant” which shows photographs of F.delavayi at different locations to players. The concept is to click on the plant as fast as they can. When they checked the results, it was as expected. The volunteers took a long time to identify the dabber colours. This correlated to the theory that the populations which were left undisturbed, it was brightly coloured. But the heavily harvested populations had duller appearances. This might be the first example of a plant being threatened to change according to its environment.
Left- Camouflaged individuals in populations with high harvest pressure | Credits: Current Biology (2020)
The biologist Jill Anderson from the University of Georgia commented- “ Humans go into a population and harvest the most visible plants they can find and [Harvested plants] no longer have the capacity to contribute to the next generation, whereas the camouflaging plants can live out their life cycles. It’s a process of natural selection in these populations.”
F.delavayi takes five years to reproduce and these vibrant bulbs could have been harvested before it could transfer the colour genes. In a generation or two, the heavily harvested plants could have a gene pool with grey and brown DNA (the genetic analysis hasn’t been completed yet). So in a short period, its quite possible for F.delavayi to have evolved.
These defensive mechanisms adopted by F.delavayi might pave the way to some challenges such as pollination and photosynthetic activity. Pollination might be difficult as pollen vectors would find it trickier to spot the herb. The activity of photosynthesis could also be impaired by the discolouration to match the environment.
In the end, we humans have been manipulating species for ages to artificially select based on our needs. This is, however an example of unintended selection as a defence mechanism. Along with the increasing demand for this small herb the Chinese government is currently updating Fritillaria delavayi’s conservation status to represent stronger defences against the growing threat.
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