Attention, spectators, this kind of melon cannot be eaten!

Review expert: Hu Jiayu, Master of Botany, University of Chinese Academy of Sciences

When traveling in the desert, you will be scorched by the scorching sun while enjoying the beautiful scenery. The mineral water you carry with you will also become warm. At this time, it would be so refreshing to have a cold watermelon! At this time, you will be surprised to find that there are many "watermelons" with green skin growing in the desert!

However, just as you were about to enjoy a feast, you were stopped by the tour guide. Upon closer inspection, you will find that these "watermelons" are very different from the watermelons we usually see.

Watermelon in the desert

Source: Wikipedia/Ji-Elle

In fact, this kind of "watermelon" is not edible. It is not the sweet and juicy fruit we imagine. On the contrary, this species is extremely poisonous. So who are these watermelons? Why do they look like watermelons but are deadly poisons? How can we distinguish between the two? Let's learn the mystery behind it today.

Why can’t we eat watermelons in the desert?

These "watermelons" in the desert are actually called medicinal watermelons (Citrullus colocynthis). Like ordinary watermelons, they are all plants of the genus Citrullus in the Cucurbitaceae family. Medicinal watermelons are widely distributed, and their origin is tropical Asia and Africa. At present, their distribution range has expanded to Australia, West Asia, Spain and other regions.

Medicinal watermelon has certain medical value. It can clear away heat and reduce fire, strengthen the stomach and help digestion. In some areas, it is used to treat stomach problems such as indigestion and as a laxative, hence the name "medicinal watermelon".

Source of medicinal watermelon丨Wikipedia

After scientists extracted and separated the medicinal watermelon samples with ethanol, they identified that they contained triterpenoid saponins, triterpenoids and alkaloids. These compounds, when mixed together, would form a highly toxic substance, causing the entire body of the medicinal watermelon to be full of toxicity.

Medicinal watermelons grow in the desert and have less water inside, but their vines and rhizomes still have juice, which is highly corrosive and will cause a burning sensation if it comes into contact with the skin. If not treated in time, the skin will ulcerate. The flesh of medicinal watermelons is the most dangerous. Eating it can affect human body functions, causing headaches and diarrhea at the mildest, and organ failure and even life-threatening conditions at the worst.

The distribution source of medicinal watermelon丨https://gbif.org

All parts of the medicinal watermelon are poisonous and can even be used to make pesticides. If eaten by mistake, it can cause headaches, diarrhea and other symptoms. The reason why the medicinal watermelon is poisonous is to prevent it from being eaten by animals such as camels in the desert. It is the result of evolution after biological natural selection.

What is the difference between medicinal watermelon and ordinary watermelon?

Compared with ordinary watermelons, the living environment of medicinal watermelons is very different. It can grow in extreme conditions such as the desert, so it has some unique characteristics that can help it adapt to the desert environment.

Source of medicinal watermelon: Wikipedia/H. Zell

The first is the size of the two. The fruit of the medicinal watermelon is relatively small, with a diameter of 5 to 12 cm, usually only one-third the size of an ordinary watermelon, and about the size of a tennis ball. This is because the desert environment lacks water, and plants need a smaller body to grow easily. Therefore, the desert watermelon has evolved smaller fruits to reduce its own water demand.

Ripe and dried medicinal watermelon Source: Wikipedia/Jacopo188

Secondly, the flesh of medicinal watermelon is also quite different from that of watermelon. Generally speaking, the flesh of watermelon we are familiar with is usually red (this is the result of continuous agricultural breeding, and the flesh of wild watermelon is originally white), while the flesh of medicinal watermelon is white like sponge flocs, which is almost the same as gourd flesh.

A familiar face in the desert

Of course, in addition to medicinal watermelons, there are many plants in the desert that can survive the harsh conditions. For example, when people mention the desert, they will think of cacti . They have fleshy stems and thorns that can be used to store water to adapt to the extreme conditions of the desert. At the same time, they survive by photosynthesis, absorbing the harsh sunlight in the desert through chlorophyll and converting it into energy.

In addition, there are some plants that live in the desert like the medicinal watermelon, but have the same name as normal plants. Desert rose is one of them. It is a plant of the Apocynaceae family, native to Kenya and Tanzania in Africa. It is named "desert rose" because its origin is close to the desert and its flowers are as red as roses.

Traditional roses usually require more water and moderate temperatures to grow, while desert roses prefer warmth and dryness and avoid water and humidity, and are more adaptable to dry and high temperature environments.

Desert Rose Source: Wikipedia/Nevit Dilmen

There is also the Elaeagnus angustifolia , which is called "the date in the desert", but it actually belongs to the genus Elaeagnus in the family Elaeagnaceae. Elaeagnus angustifolia likes light, is cold-resistant, has strong drought tolerance, and has a well-developed root system, so it is very suitable for survival in desert areas. Many areas also plant Elaeagnus angustifolia to prevent wind and fix sand.

Elaeagnus angustifolia is closely related to traditional culture in Xinjiang, my country. There is a story about Elaeagnus angustifolia in the famous Afanti story. The story tells of a child who was too lazy to bend down to pick up a piece of waste horseshoe, which was then picked up by Afanti and sold for 50 Elaeagnus angustifolia. When the child was hungry and thirsty during the journey, Afanti would drop a Elaeagnus angustifolia for the child to pick up at intervals. In this way, the child bent down 50 times because of laziness.

Fruit of Elaeagnus angustifolia

Source: Wikipedia/Roger Culos

In addition to the sand date, there are some edible fruits in the desert, such as sea buckthorn fruit and cactus fruit , but it is still recommended that friends follow the principle of "don't eat unfamiliar plants" when traveling.

After all, there may be something like the medicinal watermelon, which may look familiar but is not a "tough guy", so it is better to be careful.