Cacti belong to the family of perennial succulent flowering plants. Evolutionarily, cacti appeared about 30-40 million years ago. The spines of a cactus are not a whim of nature, but an organ of survival that has appeared in the process of evolution.
What are thorns
Spines are a living part of the plant. The thorns consist of organic matter, similar in structure to chitin, of which the skeleton of insects consists. The thorns contain a large amount of mineral salts, in particular calcium carbonate. The soil must contain enough calcium for thorns to form. That is why a little marble chips or old plaster should be added to the substrate for growing prickly and pubescent cactus species.
What are thorns for?
In different types of cacti, the thorns differ in shape, color and purpose. Cactus spines are short and long, hard and soft, straight and curved, hair-like or down-like. The purpose of the thorns depends on the place where the plant grows.
The thorns of the cactus are used to save moisture. In the arid conditions of the desert, the evaporating surface of the leaves is an unaffordable luxury. In the course of evolution, the leaves have changed, become thinner and sharper. Over time, the leaves turned into thorns and completely lost the ability to photosynthesize. The photosynthetic function has been transferred to the plant stem.
The thorns protect the cactus from heat. Many light-colored needles reflect most of the sun's rays. White hair tufts have the same function. In some species, the cactus itself completely hides the fluff.
The thorns have the ability to deliver the necessary moisture to the cactus. In places where cacti grow, there is no rain for months. Daily temperature drops in such an area range from + 2 ° C at night to + 50 ° C during the day. Under such conditions, dew is formed, which serves as the main source of water for cacti. On an adult cactus, each thorn assimilates its portion of moisture for the plant. Some types of cacti have a poorly developed root system, so thorns are the main organ of water supply for them.
Long, hard and sharp thorns are inherent in cacti that grow in areas with a milder climate. These territories are inhabited by animals for which cacti serve as food. To protect against herbivores, cacti use their thorns.
Some cactus species have spines that secrete nectar to attract pollinating insects. These cacti include representatives of the genera Coryphanta and Ferocactus.
Interesting facts about thorns
Not all cacti have thorns. The stems of such plants are densely shrouded in long hairs that form a soft white coat. Such a coat reflects sunlight well and protects the cactus from the cold.
There are quite unusual spines - papery. Only 4 types of cacti have such soft and flexible thorns, as if cut out of thick paper.
The maximum length of spines in cacti is 25 cm.
