Why Do Cactus Have Thorns?

Thorns or spines help cacti to survive in deserts by dissuading herbivores (plant-eating animals) from eating the cactus. They give shade, help to control temperature, decrease water loss and even help the plant to reproduce. Over the years, the leaves transformed into the spines seen on cactuses these days because they help the plants to flourish in arid conditions.

About Cactus

 A cactus belongs to the Cactaceae family of plants, with 127 genera and 1750 species in the order Caryophyllales. The term “cactus” comes from the Ancient Greek o, Kaktus, a name given to a prickly plant by Theophrastus that is now unknown. 

Cacti exist in a wide range of sizes and shapes. The majority of cacti are found in areas where there is at least little drought. 

Cacti have a variety of water-saving adaptations. Succulents have enlarged, fleshy sections that have evolved to store water, and almost all cacti are succulents. The thorny spines are so common in cactus plants.

Why Do Cacti Have Spines?

Cactus spines have a crucial role in protecting cactus from predators such as animals and people. True leaves and branches are absent in the majority of cactus species. Instead, they have areoles — small bumps out of which spines grow – which have been substantially changed. 

Cactus spines are highly transformed leaves. Cactus leaves are not like those of a maple and oak tree. However, they may have had leaves that were at least somewhat similar to that in the past. Because they enable the plants to thrive in hot, dry areas, those leaves developed into the prickly spines you see on cactuses today.

Spine’s Functions

The spines on a cactus serve the following purposes. Because water is scarce in a desert, the spines prevent excessive evaporation. 

The spines also trap air, preventing evaporation and restricting ventilation. 

Early in the morning, fog collects as dew on the spines. 

The dew is gathered and liquified into the water before falling to the earth below. After that, the plant absorbs the water.

What Do Thorns And Spines Have In Common?

Many plants possess thorns, and only a few have spines, despite the fact that they sometimes appear to be the same. So, what’s the difference between the two? 

Thorns are modified stems that develop instead of buds in the axil of the leaves, whereas spines are the highly transformed leaves. All plants with thorns have leaves of some kind. 

Plants with spines don’t have leaves since the spines themselves are the leaves. 

Thorns are deeply embedded whereas spines are not.

Roses’ thorns are actually prickles. Prickles differ from spines and thorns in that they are sharp projections of the stem or leaf epidermis.

Are Cactus Spines Poisonous?

The spines of cactus are not toxic. They can, however, do a lot of harm to your skin, especially the ones with barbed spines. 

Barbed spines are meant to detach from the animal or human when they come into contact with and lodge in the skin. These spines are difficult to eliminate and, if left untreated, might cause regional dermatitis or a granulomatous reaction. 

Opuntia cactus contain short spines that can become stuck in your skin and be tough to remove. They may irritate the skin and cause a lot of discomforts. 

With a pair of tweezers, people have spent countless hours trying to remove prickly pear spines out of skin.

Do Cactus Spines Regenerate?

As the plant matures, spines develop from the areoles. Damaged or removed mature spines are inactive, and they will not regrow. As the cactus expands, new areoles will produce new spines. Handle cactus with care if you’re growing them as attractive plants, as the visual damage caused by hurting or shattering spines is permanent.

Do Cacti have leaves?

The majority of cacti species have lost their actual leaves, leaving just spines, which are highly transformed leaves, behind. Spines help reduce water loss by restricting air flow around the cactus and giving some shade, in addition to guarding against herbivores. 

In the absence of leaves, photosynthesis is carried out by larger stems. 

Leaf cactus (genus Epiphyllum), sometimes known as orchid cactus, is a genus of roughly 15 cacti (family Cactaceae) native to tropical and subtropical America, as well as the West Indies. The plants are primarily epiphytic (meaning they grow on other plants), but they do occasionally sprout from the ground.

Do cacti have roots?

Roots are found on all cacti and provide a variety of purposes for the plants. Cacti’s roots anchor them in the ground, absorb water and nutrients, and store food and water in addition to the water stored in the succulent stem tissues. 

Cactuses’ stems retain a lot of water and nutrients, and their growth is gradual to begin with. This indicates that many cacti have already stored more than they require for a long period. 

Some cactuses can also alter their stems to enable them to collect water and nutrients more slowly and inefficiently than roots.

Can a cactus grow without roots?

Stem cuttings can be used to grow a variety of cacti. Stem cuttings are taken from an established plant then dried and calloused before being used. 

The cuttings will develop roots and grow as a new plant from the cut end. A cactus’ root system is one of a kind. 

To allow the cactus to absorb as much water as possible, the plant must obtain water deep from the earth and disperse it as broadly as is possible. Cactus roots may grow three feet deep, three feet wide, and three feet long, as well as horizontally.

Do cacti have stems?

Cacti have plump, soft, green and photosynthetic stems storing water inside them and have a thick waxy coating all over the stem to prevent water from evaporating. Cactus pads are also cactus stems. 

Cactus stems have many cushion- and pit-like structures on their surface known as areoles, from which clusters of spines normally emerge.

Areoles are commonly viewed as incompletely formed axillary stem branches in developmental biology.

The Cacti are succulent plants with scales as well as spines instead of leaves on their stems, pads, or branches. 

The prickly spines are adapted leaves that help shade the stem by breaking up the evaporative winds flowing across the pad surfaces. Cacti are plants that live for a long time. 


Cacti have thorns or spines that help these plants to survive in arid conditions, protect them from predators, and provide shade. The prickly spines are adapted leaves that help shade the stem by breaking up the evaporative winds flowing across the pad surfaces. 


Nikita is a Succulent lover. She really enjoys planting and nourishing them. She loves to share information about various Succulents on this blog to aware people more about these awesome plants.

Recent Posts