Why are Cactuses Round, or A Lesson in Geometry from Nature

In the year before last, for the sake of the experiment, I decided to capture the changes that occur to mammary after the first spring irrigation. Since November, it stood on a cool window sill and did not see water until March. It is not me who lives, it is a normal practice in growing cacti – called dry overwintering.

Slow metabolism of these plants is known to almost everyone, but if it was not for him, spring metamorphosis and would not be so valuable and attractive to the nerdy collector! And the fact is that without water, like any other plant, the cactus shrinks, but as soon as you water it, it immediately spreads its shoulders. Here, take a look.

The difference between photos is only two days. Other plants will not show you such a miracle (and in a few months without watering they will just move horses). But for cactuses and many other succulents, this mechanism is more than usual, because life in extreme conditions rarely turns to these ascetics face. You have to endure a drought while waiting, and quickly stock up on water when it rains rarely.

Why do cactuses need a strange stem shape?

It’s all about volume. The larger it is, the more moisture the plant can hold. As the cactus runs out of water from its tissues, it shrinks and thus shifts to more and more economical use of resources by reducing its evaporation area. When the reserve is replenished again, the wastefulness in evaporation of moisture will not only be not dangerous, but also justified: after all, a cactus is not a watermelon, if by some strange coincidence the rain will last for a week, it is better to evaporate excess moisture with less risk of bursting and rotting from it.

Well, fans of geometry know that it is the ball has the largest ratio of surface area to volume figure. But round cactuses with ribs and hillocks have gone further: in the “improved” nature form of water will fit even more. By the way, the relief surface of cactuses has another important function: ribs and bumps with thorns cast a shadow on the stem, significantly reducing the risk of burns.

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