How Do Cactus Store Water?

How Do Cactus Store Water?

Succulents and cacti are survivors because they can withstand arid deserts. They are equipped with sap-filled plant parts that sustain them when there is no moisture or water to nourish the roots. Cactus is a member of the family Cactaceae with at least 1,750 known species. The plant comes in a vast range of shapes and sizes, and almost all are succulents although a few are not.

How do cactus store water?

Cactus store water in their stems through water storage cells. The cells improve the water storage space within the stems by increasing the surface area. This leads to a more enhanced ability to store water. Other types of cacti store water in their root system. These plants can absorb and retain water for a long period. 

Cacti have succulent stems that are thick and hard-walled where the water is stored after rain. The stems are green, fleshy, and photosynthetic. The outer part allows the cacti to absorb carbon dioxide utilized in photosynthesis. 

The inner part of the plant is spongy or hollow depending on the variety of cactus. This innermost layer is succulent and has numerous collapsible water storage cells that keep the cacti hydrated and healthy despite prolonged dry spells. The cells have an elastic and lignified wall along with fewer chloroplasts. It allows the shape and volume to change once water is absorbed or released.

The water does not evaporate inside the stems because of the thick and waxy coating. Cacti also have long and fibrous roots that absorb moisture from the soil although some species such as the ball cacti have compact roots that absorb dew water. 

Cacti plants do not have leaves but instead, have spines or scales. These plant parts do not lose water through evaporation. They protect the plants from predators or animals that consume the cactus for food and water. The circular clusters of spines are called areoles.

What are the basic adaptations that help cacti to survive better and to prevent water loss?  

These are the basic adaptations:

  • Cacti modified leaves to spines to retain water better by minimizing transpiration. 
  • An intense system of underground water collection and the atmosphere through spines and a vast root system. 
  • Spines as a form of defense.
  • Spines obtain water from a deep fog and the collected water is stored in the mucilage cells of the stem. The mucilage cells make the plants slimy when cut and form a predominantly carbohydrate tissue that can bind and hold water. 

Do cacti have roots that help in collecting water?

Affirmative. These roots are deep and branched and able to sense underground water reservoirs.

These are the types of cacti roots:

1. Aerial roots 

This root is uncommon. It tends to rise to the surface when the soil does not have enough water. Aerial roots collect vapors of water from the environment. 

2. Lateral roots 

These roots are common. They are hairy and grow in clusters. They cover a lot of subterranean areas to absorb as much moisture as possible. The roots are essential to exploit every last bit of water available.

3. Tap roots 

These roots are the anchors of cacti plants. . The roots go deep in search of water from underground reserves.  These roots are the first to develop and last throughout the plants’ lifetime. 

How long can a cactus store water?

That will depend on the type of cactus, its size, and the environment. There is no need to water the cacti during the winter season. Barrel cacti can survive for months without water while other species can retain water for up to two years.


Cacti, just like most succulents, are hardy. These plants store water in their stems with the help of storage cells and water is collected through the spines and roots. This amazing flora can store water for up to two years depending on the type, size, and environment. 

Image: / IKvyatkovskaya