How Do Plants Survive in the Desert?

Take a moment and imagine that you live in the Sahara desert. Not in a house, or a tent, but outside, with the sun, sand and vultures. Now imagine that the only water you have access to in your desert oasis is rainwater.

Most areas of the Sahara desert receive less than 2 cm of rain a year. Would you be worried about not getting enough water? You should be! What would you do to make sure that you didn’t end up dehydrated? 

Let’s see if the way plants survive in this environment gives us some ideas.

What is the epidermis, and what does it do?

Both plants and animals have bodies made up of many layers of cells. The outermost layer is the epidermis. In humans and animals, the epidermis is our skin. A plant’s epidermis is very important for protection.

It protects the plant from many things:

• desiccation (drying out)
• ultraviolet (UV) radiation 
• foreign particles such as viruses
• insects
• many other things that may harm the plant. 

What is a plant cuticle?

Most of the protection you just read about comes from the cuticle, a waxy layer over the epidermis. It covers the parts of a plant that are exposed to air.

The cuticle contains polymers called cutin and cutan. It also covers several types of wax. These materials are hydrophobic, which literally means “water fearing.” The hydrophobic materials make the cuticle waterproof. This is useful, because it keeps water from evaporating out of the plant. 

What is the stomata, and what does it do?

Like all living things, plants need cells that allow them to exchange gases with their surroundings. Humans breathe in oxygen and exhale carbon dioxide through a process called respiration. Plants do the opposite: they release oxygen and take in carbon dioxide through a process called photosynthesis. Unlike animals, plants do not have mouths to breathe through. The epidermis of a plant contains small openings called stomata (singular: stoma). Each stoma is surrounded by guard cells which can open and close the stoma. Guard cells let gases and water travel in and out of the plant as it needs.  

Stomata are found in different locations on different plant species. This means the epidermis of each species has a unique pattern! When plants die in an area with lots of rocks, this pattern can become fossilized on nearby rocks. This pattern is useful for palaeobotanists, scientists who study fossilized plant remains. They can use these patterns to identify and classify the types of plants that were in an area long after the plants have died.  

Did you know?

Human fingerprints are completely unique. Though plant fingerprints are sometimes unique to the individual, most often they are unique to a particular plant taxon or group.

Summing up

The evolution of the plant cuticle is one of the most important adaptations in plants. The features you have read about are common to all land plants, not just desert plants. But you can probably see how they are especially useful for plants in the desert!

So let’s get back to you. If you lived in the desert, what would you do to stay hydrated? Wouldn’t it be funny if you could slather yourself in earwax to stay hydrated?

Lucky for us, we can think and move around. This makes it a lot easier to locate water when we need it!