We are increasingly becoming aware of the importance of camouflage in the plant kingdom. By blending in with their surroundings, some plants are able to avoid attention from hungry herbivores. Amazingly, a recent investigation in Hengduan Mountains of southwest China has revealed that it can also help plants avoid being harvested for the herbal trade.

Fritillaria delavayi is a tiny, alpine plant that grows among the rocky scree at high elevations in the Hengduan Mountains. It is a slow growing plant that can take upwards of 5 years to produce its first flower. It is also variable in its overall coloration. Some populations consist of plants with green leaves and bright yellow flowers, whereas other populations consist of plants with leaves and flowers in various shades of brown that cause them to blend in with the surrounding rock.

Variation in plant coloration is not terribly novel. Many plant populations can differ from one another in their overall appearance, however, there seems to be a pattern among F. delavayi. It would seem that plants growing in more accessible places tend to be brown whereas plants growing in less accessible places tend to be green and yellow. Interestingly, herbivores don’t seem to explain these differences. Indeed, F. delavayi is chock full of toxic alkaloids that deter what few herbivores exist at such high elevations. Nonetheless, it is the presence of those alkaloids that explain why populations differ so much from one area to the next.

(A and B) Normal green individuals in populations with low harvest pressure. (C and D) Camouflaged individuals in populations with high harvest pressure [SOURCE]

Because of their purported medicinal value, the demand for F. delavayi bulbs has greatly increased over time. Each year more and more people are heading to these mountains to harvest the plants to sell them in herbal markets. This led a team of researchers to investigate if harvesting by humans could explain color variations among populations.

Amazingly, it did! By looking at ease of access and harvesting, researchers found that plants that were in hard to reach areas or places where harvesting is difficult were more likely to have bright green leaves and yellow flowers. By contrast, plants in easy to reach locations that were not difficult to harvest were more likely to be brown. The researchers even went the extra mile and tested how easily plants of each coloration could be found by humans. Not surprisingly, it took humans much longer to find brown plants that it did for them to find green plants.

Based on their findings, researchers have concluded that harvesting pressures are changing F. delavayi populations in the Hengduan Mountains. Because they are harder to detect and therefore less likely to be harvested, plants sporting the brown coloration are far more likely to survive and reproduce in highly trafficked areas, resulting in an increase in camouflaged offspring. Alternatively, populations growing in hard to reach areas do not experience such heavy selection pressures and can continue to safely sport bright green leaves and yellow flowers. It just goes to show you that human activities can often have unintended consequences for other species. This research also raises the question of how humans have shaped the defensive strategies of other highly sought after plant species.

Photo Credits: [1] [2]

Further Reading: [1]

Look closely or you might miss it. The gravel ghost (Atrichoseris platyphylla) is a master of disguise. At home in a small pocket of southwestern North America, this wonderful member of the aster family only puts on a show when rains offer the parched landscape a momentary reprieve.

The gravel ghost is the only member of the genus Atrichoseris. It is different enough from the rest of the chicory tribe (Cichorieae) to warrant its monotypic status. The gravel ghost is a winter annual meaning its seeds germinate at some point in the fall and the plant spends most of the winter putting on growth. As you can probably imagine, life in this corner of the world is pretty tough. Rain is sparse to non-existent and many plants teeter on the edge of desiccation. The fleshy, semi-succulent leaves of the gravel ghost likely store just enough water to offer some insurance against prolonged drought.

As if drying up wasn’t enough for this plant, the desert’s compliment of hungry herbivores are constantly on the lookout for any plant remotely alive that can offer sustenance. All it takes is a few encounters with the gravel ghost to understand how this plant manages to avoid as much attention as possible. As its common name suggests, this species blends in with the surrounding soil to an extreme degree. From what I can gather, there appears to be a lot of variation in gravel ghost leaf color depending on where the population is growing.

Some are mostly green whereas others take on a mottled grey hue. Still others seem to have settled on a mixture of browns. It seems that no matter the substrate, the gravel ghost will do its best to blend in. Personally, I would love to see someone investigate what kind of genetic or environmental controls dictate leaf color in this species. It is fascinating to think about how plants can disguise themselves against herbivores.

Starting in late winter and early spring, the gravel ghost needs to complete its annual life cycle. When rains punctuate the drought, the gravel ghost sends up a spindly inflorescence tipped with a few flower heads. If they are lucky, some stalks will avoid being nipped off by sheep and rabbits. Those that do put on quite a floral display. Each head or ‘capitulum’ explodes with clusters of bright white ray flowers. Only at this point does its affinity with the chicory tribe become apparent.

The need for such a high impact floral display has everything to do with being an annual. There is only limited time for pollination and seed set. Each gravel ghost must produce enough seeds to enure that at least some survive. They simply don’t have multiple seasons to reproduction. Luckily its a member of the aster family and the opportunity for seed production is usually relatively high. With any luck, plenty of pollinators will find these plants tucked in among rocks and gravel and the process will begin again come that fall.

Photo Credit: Joey (www.instagram.com/crime_pays_but_botany_doesnt)

Further Reading: [1] [2] [3]