Adaptations of Desert Plants: Desert Survivors

Hot desert plant adaptations

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In hot, arid desert regions, one could be forgiven for thinking that not much vegetation would be able to thrive. However, with special adaptations, many plants are easily able to survive these extreme conditions.

What are Xerophytic Plants?

What are xerophytic plants?

Xerophytic plants are plants that have adapted to survive in drought conditions. These plants have mechanisms that prevent them from losing water and are found in places like deserts, salt marshes, and acid bogs.

Perhaps one of the most well-known types of xerophytic plants is the cactus, of which there are many species. But one thing they all have in common is a thick skin for storing water and the ability to drop leaves (some have none at all) during periods of drought.

Xerophytic plants are able to store water and plants with this ability are known as succulents. This, along with other adaptations that we will discuss at length in this article, allow them to thrive in conditions where other plants would quickly die.

Main Challenges for Plants in the Desert

Main challenges for plants in the desert

Desert plants really do have their work cut out for them just to survive. For example, they not only have to contend with super-hot temperatures and a lack of water during the day but in some deserts, night time temperatures can drop to freezing!

1. Lack of Rainfall

When most of us think of a hot desert, we imagine somewhere with very little water, and that’s a correct assumption. In some cases, deserts can go many years without any rainfall, and there’s one area in northern Chile where it never rains. Plants here can only collect moisture from the morning dew that settles on them.

While annual average rainfall statistics are given to deserts, these are pretty unreliable. For example, an area that has 5 inches (13 cm) of rainfall a year may not experience this consistently. Year one may see five inches, while year two may see none followed by a third year with fifteen inches. So, any plant life that lives in these regions must be able to cope with this inconsistent rainfall as well as coping without as much water as other parts of the world.

2. Nutrient Poor Soils

In a desert environment, there is not as much organic matter that decomposes into the soil and this means that there is a serious lack of nutrients like nitrogen, potassium, and phosphorus, which are all important to the growth and health of many plant species.

Instead, the soil in these regions tends to be much richer in minerals and is far less acidic. For example, in some deserts, there are calcium carbonate layers within the soil that are as deep as 165 feet (50 meters).

3. Extreme Temperature Variations

The temperature that most people think of when thinking about the desert is hot, hot, hot! This is very true because in some regions, the mercury can rise above 100ºF (37.8°C) during the peak of the day, and this happens for most of the year. The highest ever recorded temperature on earth occurred in the Sahara desert of North Africa and soared to more than 136ºF (57.8°C).

However, hot temperatures aren’t the only thing that these plants have to rise above because, in many hot deserts, things can drop to as cold as freezing once the sun goes down. This means that some deserts may experience a nighttime temperature drop of as much as 40 degrees!

4. High Evaporation Rates

As we have learned, there is not a lot of rainfall in the desert, but another issue here is that the rate of evaporation will often exceed the rate of rainfall, throwing everything out of balance. There are also regular instances of rain falling and being evaporated before it’s even had a chance to reach the ground.

It’s the high daytime temperatures that are largely to blame for this evaporation, but when the wind picks up, the warm, moving air can increase evaporation speeds even further. In American deserts, there could be as much as 160 inches (406 cm) of evaporation each year when the average desert may only receive 10 inches (25 cm) of rainfall.

5. Deep Groundwater

Everywhere in the world has a water table, but it’s just that, in the desert, it’s much further under the ground. It was once discovered that the water table under the Nevada desert was as deep as 1500 feet (457 meters), and in Africa, it’s thought that there is up to 100 times more water buried deep under the ground than there is on the surface.

These underwater reserves are known as aquifers, and it’s thought that they contain most of the world’s water. The problem is that even shallow aquifers could be up to 0.6 miles (1 km) below the surface.

Of course, the major problem with how deep groundwater is in the desert is that plants need very long roots to access it.

Common Characteristics of Hot Desert Plants

Common characteristics of hot desert plants

Regular plants just wouldn’t be able to cope with the challenges of the desert. So, plants that live here have special adaptations to help them make the most of what little water is available.

Narrow Leaves or Spines

Leaves are used to help plants release moisture but in the desert that’s the opposite of what they need. This process is called transpiration, and having a smaller surface area means that the plant does not lose as much water. This is why you often see succulents with spines as opposed to large leaves.

On top of this, having spines acts as a form of self-defense for the plant and stops animals from attacking it.

Where desert plants do have leaves, they may be covered in small hairs that act as a sunshade. The less sunlight on the leaves, the less chance there will be of moisture evaporating. A lot of leaves are also much lighter in color as a way of reflecting the sun back off them.

Most plants will photosynthesize, but this requires small holes called stomata, in the leaves to remain open. Having these open can increase how much water the plant loses, so in desert species, they will often stay closed until after sundown, when they’ll open up to absorb carbon dioxide without losing water.

Waxy Coating

Another way that desert plants reduce transpiration is by having a waxy coating that stops water from evaporating and seals it inside the plant. This isn’t a feature seen in all desert plants, but things like the creosote bush have a waxy surface.

Long Tap Roots

In order to reach the deep ground water under the surface of the desert, some plants have very long tap roots. These plants are known as phreatophytes, and their roots are easily long enough to reach the water table. Even in times of severe drought, the plant is able to obtain the water it needs.

The longest known tap roots belong to mesquites which can reach lengths of more than 80 feet (24 meters)!

Wide & Shallow Root Systems

Some plants do not have long roots but instead spread their roots much wider and a lot closer to the surface. The benefit of this is that they are able to take maximum advantage of any rainfall as soon as it happens to avoid evaporation, and are also able to cover a much wider area.

Because these species of plant need to have a wider spread for their roots, they don’t tend to grow in groups but much further apart.

Some Have Pleats or are Funnel Shaped

There are some desert plants that have pleats that are able to expand and contract with the rainfall. When it rains, the pleats will expand to let in water but will then close again when the rain stops to retain any water it has caught.

Other desert plants are funnel-shaped in order to send water directly to the center where it can be stored and absorbed by the roots as needed.

Die Back or are Dormant During Drought Conditions

When there is a serious lack of rainfall, some plants will enter a state of almost complete dormancy in order to survive. Interestingly, there are some species that will drop their leaves in order to lose less water in times of drought. These are known as drought deciduous species.

Dessert perennials will remain dormant for large parts of the year and will seemingly spring back to life when there is rainfall. During this time, new leaves will quickly grow, and the plant will flower and go to seed within a few short weeks.

Can Store Water

Plants that are able to store water are known as succulents and they have lots of places to keep this moisture including the stems, roots, and leaves. They will hold onto this moisture for as long as needed and will absorb it when rainfall is most scarce.

As I discussed earlier, some plants have pleats or folds that they use to store water, and these can expand so much that the plant becomes spherical, allowing it to store a lot more water.

Usually Grow Slowly

Owing to the fact that there is not a lot of water in the desert, it’ll come as no surprise that plants here do not grow as quickly. But when they do grow, they do not need as much energy to do this, which is good news considering the conditions.

Plants in the desert must balance out their need to store water with their need to absorb carbon dioxide and have adapted to do this. That said, there are some desert plants that have adapted ways of speeding up their growth.

Hot Dessert Plants with Remarkable Survival Strategies

Deserts are some of the harshest environments for plants to survive in. However, many plant species have evolved unique adaptions that allow them to thrive in these hot and arid environments. In this section, we’ll explore some desert plants that have developed remarkable survival strategies.

1. Resurrection Plant (Selaginella lepidophylla)

Spike moss, more commonly known as the resurrection plant, is actually a type of tumbleweed. It takes its name from the way that it appears to come back from the dead after losing up; to 95% of its moisture and going into a state of dormancy. During this phase, it shrivels up into a ball and to the untrained eye, looks all but dead.

These plants will then reactivate when rain falls and will turn into a lush green plant that resembles a fern. At this point, the plant is able to continue photosynthesizing and growing as if nothing had ever happened.

These plants grow natively in the Chihuahuan Desert of Mexico and the southwestern United States.

2. Saguaro Cactus (Carnegiea gigantea)

The Saguaro cactus is a succulent that’s native to parts of North America including California, Arizona, and Mexico. These giant cacti can grow up to 50 feet (15 meters), although they do so very slowly, owing to the poor growing conditions. However, some can live up to 200 years.

The Saguaro is a type of pleated cactus, so when it rains, these pleats will expand, allowing it to collect water. They will then contract again in dry periods to conserve moisture. The waxy skin helps to reduce transpiration meaning the cactus is more easily able to retain water.

In addition to this, the Saguaro cactus performs CAM photosynthesis, meaning it only exchanges gasses at night to prevent moisture loss. The spines which are in place of regular leaves prevent it from being able to photosynthesize as normal.

3. Creosote Bush (Larrea tridentata)

Creosote bushes are mainly found in the deserts of North America and are shrubs that can get as large as 10 feet (3 meters). Unlike a lot of desert plants, these bushes are able to photosynthesize. However, it will only open its stomata in the mornings when the temperature isn’t too hot. Moreover, these plants always face in the same direction to absorb as much morning sun as possible.

Their leaves are covered in a wax-like coating to reflect heat and stop transpiration. The plant has a cone shape, allowing water to flow down inside it.

The creosote bush, sometimes called the desert greasewood, gives off a distinct odor that is similar to the wood treatment of the same name and has a bitter taste that repels predators.

4. Brittlebush (Encelia farinosa)

The brittlebush can be found in the Sonoran desert as well as some of the hotter parts of the Mojave Desert and prefers rocky areas. These small plants are members of the sunflower family and cannot tolerate cold conditions.

However, they’re perfectly formed for the desert, with small white hairs covering their leaves to protect them from the sun. On top of this, as the weather gets hotter, the plant’s leaves get smaller to reduce water loss. When there is little rainfall, the plant will not flower to further conserve its resources.

For anyone living in an arid region and attempting to grow brittlebush, it’s essential to remember not to water it too frequently, as this can do more harm than good.

5. Teddy Bear Cholla (Cylindropuntia bigelovii)

The teddy bear cholla has a pretty misleading name since it’s anything but cuddly, despite appearing that way from a distance. These desert plants have 2.5-inch (6 cm) spikes and are found in parts of North America, including California, Colorado, and Mexico. The spines are designed to cast a shadow over the plant, protecting it from the heat of the sun.

One of the ways that these plants survive is by relying on animals to help them reproduce. The teddy bear cholla can break into pieces, and these pieces get stuck to passing creatures who will transport them. Once the pieces fall off, they’re able to root into the ground, and a new plant is formed.

6. Ocotillo (Fouquieria splendens)

Many believe the ocotillo to be a type of cacti, but it isn’t. This plant is tall with spiny branches that have been used for centuries by Native Americans as fencing. They’re also used by humans in alternative medicine.

This abundant plant is a prime food source for hummingbirds and grows throughout the Sonoran desert.

The ocotillo is a drought-deciduous plant, shedding its leaves when there isn’t a lot of rainfall as a way of preventing transpiration. However, when rain falls, the leaves can grow back in as little as five days. The roots are widely spread and very shallow, allowing the plant to collect water quickly before it evaporates.

7. Prickly Pear Cactus (Opuntia spp.)

The prickly pear cactus is a spiny succulent that is common throughout the arid regions of the western United States. However, unlike a lot of cacti species, the prickly pear is more tolerant of cold conditions, so may be found further north.

These cacti have thick pads which hold water during periods of drought. The root systems are also very close to the surface, so the plant can collect water quickly when it rains.

The varied spikes that cover the plant not only serve as a form of defense but also cast a shadow over the cactus to protect it from the sun. Moreover, these plants only gather carbon at night.

8. Joshua Tree (Yucca brevifolia)

The Joshua tree is native to the southwestern parts of the USA in arid regions of Utah, Nevada, and Arizona. It’s also found in some northern parts of Mexico and has long been used by humans. The seeds are used for food, while the leaves are used for weaving in Native American culture.

These trees rely on the yucca moth for pollination since the flowers contain no nectar for other pollinators but these moths are able to extract pollen with their unique mouthparts.

It’s hard to determine the age of any individual Joshua tree (aptly named after the biblical leader of the same name for its outstretched branches that look like arms lifted in prayer), because of the lack of internal rings. However, it’s believed that there are some that are around 1000 years old.

9. Mesquite Tree (Prosopis spp.)

The mesquite tree is a rather unique species in that it has the longest tap roots of any known species, which can grow up to 200 feet (60 meters). This is one of the plant’s adaptations and allows it to absorb groundwater far below the surface.

These trees are also very patient in their reproduction and have seeds that can lay dormant for as long as 40 years until the rain comes and the conditions are right for germination.

Found growing in the southwestern parts of the United States, these are very common trees. They have small leaves so as to reduce moisture loss and these are covered in a waxy substance.

10. Baobab Tree (Adansonia spp.)

The baobab tree is perhaps one of the most distinct looking trees in the desert as it looks as though it is upside down. These are also some of the toughest trees being able to survive fire, drought, and a ton of other harsh conditions.

And this doesn’t dull their lifespan since they can live for 3000 years!  There was a suggestion that they could live as long as 5000 years, but carbon dating has disproved this.

Known as the tree of life because of its ability to store water in its spongy wood, the tree is also used by humans in times of drought. In its native continent of Africa, the tree also has uses in medicine, folklore, and rituals, with more than 300 known uses. However, the trees are now considered vulnerable due to climate change.

11. Nightblooming Cereus (Peniocereus greggii)

The night-blooming cereus is a type of cactus that is found growing in the Sonoran desert as well as the Chihuahuan desert in Mexico. This is a pretty distinct-looking cactus with long twisting stems and fragrant trumpet-shaped flowers which only bloom once every year.

The thick, heavy tubers store water and nutrients in periods of drought, but since these are edible, the plants are pretty sparse owing to human harvesting and animals. However, the night-blooming cereus is protected in some desert areas.

12. Date Palm (Phoenix dactylifera)

The date palm produces delicious fruits that are often eaten or used in teas and other drinks. On top of this, humans have long used the leaves in cooking.

One of the ways that these robust trees are able to survive in the desert is through their ability to store water within the trunk. They’re found in the Sahara desert where rainfall is minimal and drought is common so it’s good that the tree is able to adapt to these conditions. However, research has shown that the date palm struggles to bear fruit where the soil is too salty. Further research is going into this since the date palm is an important crop in arid countries like Oman.

13. Acacia Trees (Acacia spp.)

The acacia tree is a common sight in arid regions of Africa, particularly the savannah and has incredibly long tap roots that allow it to easily access groundwater far below the surface.

These trees are masters of self-defense with long spines. They’ve also got a symbiotic relationship with ants that live inside the tree and surprise predators should they brave the spines and take a bite.

The acacia will drop its leaves during periods of severe drought, and like some other desert plants, the seeds will only germinate when conditions are favorable, even if that means waiting.

14. Pebble Plants (Lithops spp.)

One of the most amazing adaptations of the pebble plant, also known as the living stone, is how it has developed ways of photosynthesizing despite living underground. The plant creates small windows to let in light and these also filter out UV rays which could be harmful to the plant’s survival. 

The reason that most of the plant remains underground is to protect it from the heat and sun. Only two small leaves can be seen above the surface.

To the untrained eye, pebble plants might be confused with stones but these are actually succulents that are perfectly adapted to desert conditions. The fleshy leaves are able to store water in times of drought.

15. Aloe Vera (Aloe barbadensis miller)

Aloe vera is a well-known plant hailed for its skincare and health benefits. But it’s also one of the toughest plants in the world and is easily able to survive life in the hot desert. It is native to the southeast Arabian Peninsula and Oman but is also found in Africa and the Indian Ocean islands. It is largely considered invasive.

These plants have very thick leaves and are therefore able to store copious amounts of water during a period of drought. Moreover, the skin of the leaves is very thick, preventing water loss. Furthermore, these plants perform CAM photosynthesis which is common among flora in desert environments.

While aloe vera plants can grow in the desert, they have also adapted to life in other regions and can be found growing along the coast and in grasslands.

16. Desert Indian Paintbrush (Castilleja angustifolia)

The desert Indian paintbrush is a parasitic plant meaning it attaches to other plants to take nutrients and water. This is helpful in a desert environment where water is scarce.

However, these plants are not 100% parasitic and are what are known as hemiparasitic plants. This means that, while they do better when attached to their hosts, they can survive without them.

There are more than 200 species of Indian paintbrush, and while some grow in deserts, others thrive in rainforests and temperate regions.

17. Tumbleweed (Salsola spp.)

You might be accustomed to seeing the tumbleweed in comedy sketches and cartoons, but these are real plants that use their rolling transportation to reproduce. This typically happens in the fall, and the tumbleweed detaches from the roots and blows around, dropping spores that are ‘activated’ when it rains.

One of the ways that these plants are so easily able to survive the harsh desert is that they can go without water almost completely. They’ll enter a state of dormancy and can lose up to 95% of their moisture but still come back to life when the heavens open.

Tumbleweeds are common in deserts of the USA and Mexico but they were actually brought here by Russians and are a relative of the Russian thistle.

18. Fish Hook Barrel Cactus (Ferocactus wislizeni)

It’s not difficult to spot a fish hook barrel cactus as these large, dome-shaped cacti have quite a unique appearance. Their bodies can have a diameter as big as 2 feet (0.6 meters), a height up to 10 feet (3 meters) and their colorful flowers grow directly out of the top.

These cacti are common in the Sonoran desert in Texas, Arizona, and as well as in Mexico.

The fish hook barrel cactus has plenty of space to hold water within its thick body, and the ridges help to channel water. It can live for up to 100 years. That said, these cacti don’t produce their first flowers until they’re at least 20 years old.

19. Quiver Tree (Aloidendron dichotomum)

The quiver tree, sometimes called the kokerboom is native to southern parts of Africa and is a type of succulent. They’re relatively small plants that don’t tend to get much bigger than 6.5 feet (2 meters), and they use CAM photosynthesis to conserve energy.

Since the quiver tree is exposed to a lot of sunlight, the branches have a white coating that acts as protection from this by reflecting light. The leaves grow higher up the tree and in small clusters, which helps to prevent moisture loss. Plus, the thick trunk of the tree can store water.

However, there is concern over the well-being and potential for survival of these trees due to climate change. They are very sensitive to change, although scientists hope that the potential for wider seed spread means that the trees will be able to survive.

20. Mojave Yucca (Yucca schidigera)

Found in the Mojave Desert, the yucca is a tough plant with a waxy coating that prevents it from losing moisture under the hot sun.

Amazingly, these plants can live for hundreds or even thousands of years since they are so slow growing. What’s more, they will sprout new trunks from the main trunk, and while these will drop off over time, new ones will always keep forming.

These plants are able to hold onto water and have roots that sit close to the surface, taking advantage of any rainfall as soon as it occurs. Because of this, the yucca is one of the most drought-resistant plants in the world.

21. Cardon Cactus (Pachycereus pringlei)

The cardon cactus, sometimes called the elephant cactus, is one of the most extraordinary plants in the desert. It doesn’t rely on much else than rock and has bacteria in its roots that break rock down, absorbing the nutrients to survive.

As you may be able to guess from its nickname, this is a massive cactus; the largest in the world, as it happens. It can grow up to 63 feet (19 meters) in height! Some of these plants live for hundreds of years and are found in the deserts of North America.

The cardon cactus may be one of the most well-known because of its size, but not much else is known about it since scientists find it hard to study given the harsh environment in which it lives.

22. Palo Verde Trees (Parkinsonia spp.)

The palo verde tree consists of around 12 species and can be found in North and South America as well as across Africa. While a lot of desert plants lack color, these trees are brilliantly green and covered in spines. It also drops its leaves in dry conditions.

But this lack of leaves is more than made up for by the green bark that the tree uses to photosynthesize.

Surviving the desert means being able to access water where other plants could not, so the long tap roots of the palo verde, which can grow up to 100 feet (30 meters), allow it to reach deep groundwater.

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