If you climb in the Hengduan Mountains near Yulong, China long enough, you will likely spot Fritillaria delavayi. The small, charming plants have elegant green leaves and bell-shaped yellow flowers. Everyone hits the gray rubble like a statement brooch.
Hike the same mountain range just 65 miles away and you’ll have to work a lot harder to see plants of the same species. There, F. delavayi plants, like the rocks on which they live, are dull brown. Instead, they are dark gray near Muli and reddish brown in Pujin.
Why does this one species come in so many different colors? It could hide from you.
According to an article published in Current Biology last month, F. delavayi developed different color types because humans harvest its onions. The results suggest that the plant is the latest example in a growing list of species that humans seem to have accidentally manipulated to develop new traits.
The impressive tricks that animals use to dress up are familiar to most people, but less attention is paid to camouflaging plants. Yang Niu, researcher at the Kunming Institute of Botany of the Chinese Academy of Sciences and lead author of the new paper, has documented possible examples of how plants hide for years. The mottled leaves of some forest plants can make it difficult for herbivores to see them. Lithops, also known as “living stone plants,” appear to disguise themselves as pebbles.
These plants are generally trying to fool something special. Corydalis benecincta, another alpine plant that Dr. Niu investigated “has a special enemy,” he said – a butterfly whose caterpillars nibble on the plant’s leaves. Perhaps the normally green plant has developed a more subtle gray morph in response.
“Other types of camouflaged plants that have been reported in other places around the world – they have enemies too,” he said. The different coloration of F. delavayi was initially puzzling as no animals appeared to be eating it.
But the bulbs of this and other fritillaria plants are common medicinal ingredients used to treat coughs. People have been harvesting them for over 2,000 years. What if this plant’s enemy is us? If so, F. delavayi plants should be better camouflaged in areas where there is more intensive collection than in places where people pick them less.
To test this, the researchers focused on eight plant populations. To assess crop pressures at each location, they requested records from herb dealers and used them to figure out what proportion of each F. delavayi population had been picked annually for the past six years. They also appreciated how difficult it was to collect the plants from different locations.
To determine how exactly the plants matched their background, they took rock and leaf samples from each location and compared the color and intensity of the light they reflected.
And to see if a closer match actually makes the plants harder to see, they created an online game called Spot the Plant that shows players photos of F. delavayi plants in different locations and includes quick click instructions You can. Local collectors also told the researchers that they noticed that plants were better camouflaged in certain locations, said Dr. Niu.
When they put these metrics together, they match as expected. Greening is easy enough for populations of F. delavayi that are largely left alone. But those who are under high harvest pressure are now taking a back seat, regardless of whether they are brown, red-brown or gray.
The study makes “a pretty compelling case” of humans promoting the camouflage of this plant, said Ilik Saccheri, professor of ecological genetics at the University of Liverpool who studied color changes in moths and butterflies and was not involved in the work. However, further experimentation would support the evidence.
As people continue to manipulate other species, it is good to remember that other species must take steps in response.
“Humans have been artificially selecting all kinds of plants, animals and yeasts for thousands of years,” said Dr. Saccheri. “This is a fine example of inadvertent selection.”