"In the vast expanse of yellow sand, only a few spherical cacti that can be called green plants stretch their thorns and enjoy the dazzling sunlight."
Such a long sentence to only describe a plant. "Hum, when can I write a composition like this, rather than racking my brain to hit the required word count," Mackle looked at the long sentence and thought just as other kids his age.
It's getting hot. Mackle stayed in his air conditioned room, imagining the desert life described in the book, which he actually cannot empathize with. Well, after all, he was enjoying the cool air and drinking beverages.
But this passage in the book had caught his interest. "Cacti are really tough plants. They can be found in dry deserts. They must be tougher than me. I can go days without beverages, but I can't live without water," Mackle observed.
What makes cacti tougher and drought tolerant than Mackle? The answer lies in their thick leaves and thorns.
Cacti are succulent plants. They have greater water storage capacity than other plants, and don't need to be watered every day. Cacti are drought tolerant due to some of its unique features.
First, they have thick leaves and stems that are made up of storage cells. These storage cells contain mucous materials that can prevent water loss. So their leaves and stems actually store a lot of water. This doesn't mean cacti themselves don't need water. Cacti surviving in the desert for a long time have adapted to the climate there. Their branches are empty and full of water. Second, unlike many plants with flat leaves which increase the area of water evaporation, Cacti have evolved with needle-like leaves having a waxy layer on the surface. This can reduce evaporation of water and in some way increases their water storage. Third, cacti in the desert have well-developed roots that can reach tens of meters underground. These roots are good at absorbing water and can store a lot of water. This is also an adaptation to the dry environment.
It is reasonable for cacti to be tough. They arm and enrich themselves first, then become confident in the fight against drought. I wonder whether Mackle has thought about it. Perhaps he has already known the reason why cacti are so tough.
Author: Zhu Yawen
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