Apart from the intense heat, there are several things that desert plants have to endure. Other harsh things include global warming, erosion, dust, high winds, and attack by animals and humans. Despite the harsh conditions, desert plants are still the most durable as they can leave more than 200 years. If they can survive the harsh conditions, then even disease attacks will not bring them down.
Desert plants have to adapt to all the harsh conditions to survive. The plants adjust their leaves, stems, and roots to either store water or reduce water loss. They grow strong anchorage roots that ensure storms or wind don’t pull them off the ground. The plants keep away humans and animals by their sharp spines. These are just a few of the characteristics that these plants have devised to survive and thrive in harsh environments.
There are many excellent and unique ways that desert plants such as cacti adapt to the desert. This article provides some of those ways.
How Plants Find Water in the Desert
They say water is life, and many living things, including humans, animals, and plants, depend on survival. But we’ll know that water finding water in the desert is not easy. So, how do desert plants like cactus survive the prolonged lack of water periods?
Even though desert areas are always dry for the better part of the year, they also experience sporadic rains. The desert plants absorb as much water as they can when it rains. They have different ways of accumulating and storing water for long-term use.
Some plants grow near river beds and extend their roots so deep to reach the water underground. These plants develop a kind of root called taproot that allows them to penetrate deep into the subsurface soil to find the needed moisture. These roots are capable of penetrating up to five feet into the ground.
Another way the desert plants get water to survive the extended dry seasons is through air condensation. When the air condenses, it forms dew which the cactus spines and hairs capture. They then direct the dew to the ground, where that moisture gets absorbed in the roots.
How Plants Limit Water Loss in the Desert
Because getting water in the desert is a big struggle for the plants, they don’t want to lose the little they get easily. Plants develop several adaptations to enable them to preserve water. One way these plants reduce water intake is through the reduced size of the leaves or completely no leaves.
Without the leaves, the plant won’t be losing water through transpiration. Transpiration involves the process in which plants circulate water through its body before it evaporates to the air. Plants find a way to reduce the transpiration process; hence, they don’t need to lose water or spend much energy.
Most desert plants get inactive during the dry seasons. They don’t perform many activities that consume water, such as photosynthesis. They do not grow much or reproduce. The dormancy periods enable them to survive the rough months. In case they manage to produce seeds in the dry months, the seeds remain protected in the coat. When it starts to rain, the water dissolves the coating enabling the seeds to grow rapidly.
Some plants produce a wax coating on their leaves which prevents evaporation. This protects the plants from losing water either from the inside or the surface.
Instead of developing leaves, some plants such as cacti grow spines. These spines work in many different ways to prevent water loss. These include protecting the plant against predators looking for the stored water. Other functions of the spine involve shading the plant from extreme sun and trapping moisture near the plant.
Another way desert plants survive water scarcity is by losing their leaves. When it gets too hot, the plants shed their leaves to limit water loss. One good example is the Ocotillo plant that sheds off its leaves to preserve water. They regrow these leaves when the temperatures get more favorable.
Plants like the aloe have greying color that deflects heat to prevent water loss. The aloe plant also has types of leaves that store enough water for their survival.
Some cacti and succulent plants have thick and waxy outer skin, which protects them from water loss by sealing moisture.
Root System Modifications for Survival
Some desert plants like cactus adapt to the harsh climate through various root system modifications. Most cactus plants have their roots on the surface of the soil, meaning they don’t go too deep. The plants develop fibrous roots that spread meters away from the plant.
When it rains, the roots can gather enough water from different directions. They then store this water in the stem region. The amount of stored water depends on the size of the plant. For instance, the mature saguaro is capable of storing up to 1000 liters of water.
During the rainy seasons, plants with fibrous roots shoot out more roots to absorb and store as much water as possible. When drought season comes, the extra roots dry up and break from the plant to minimize water loss. Other plants have modified root systems meant for water and food storage. They store excess water when the stem is full.
Drought Avoidance Mechanism
Some plants will not develop mechanisms to survive the harsh desert conditions but will simply avoid it altogether. Such plants die during the dry periods and come up again when it begins to rain. These plants grow and mature in a single season. They focus on germinating and producing more seeds instead of preserving energy for drought survival. These plants are called the annuals.
Most plants found in deserts such as the Sonoran desert germinate in the fall or after the summer heat and cold winter months. They rely on the small rains during fall to wet the soil, which will be enough for the germinating seeds to produce their own seeds even with no more rain.
The drought-evasive plants are known to be the most successful desert survivors. Their seeds have no metabolism and are resistant to extreme temperatures. Such seeds only sprout in particular temperatures, rain, or seasons. Even when the conditions are favorable enough, not all the seeds of such plants germinate. Some remain dormant until they reach a certain age. For instance, bluebonnet seeds will not germinate until after ten years.
The Stomata Adaptation
Another common adaptation method of desert plants is stomata. These are small pores on the leaves and stem that help in regulating the exchange of gas. The stomata of desert plants are different from those of other plants. Many desert plants lack stomata or have very small ones. They’re also far apart and few.
The reason for the limited stomata in desert plants is to limit water loss. Others practice what is known as CAM photosynthesis, whereby the plant closes the stomata during the day to limit water loss. It only opens at night when it’s cooler, and no evaporation is taking place.
The Areoles in Cacti
Plants such as cacti survive in the desert through their unique structures called the areoles. You will notice these structures in hairy parts of the cacti where spines emerge. The areoles also produce flowers in some cacti. Some leafless cacti plants have their areoles on the raised areas of the stem. You’ll notice them in oval or circular shapes separated into two parts.
The areoles give rise to spines and glochids, which act as their self-defense. They provide a protecting function that shields the plant from attack by desert animals or even humans. The spines also provide protection from sun rays and other types of conditions that can cause injuries.
Growing Thick Cuticle
Other plants manage to survive through the seasons of harsh climates by developing thick cuticles. A cuticle is a thick and waxy out layer found in most succulent plants such as cacti. In some plants, the cuticles are so thick that you can easily scratch off the wax from the plant with your fingernails.
But how does the thick cuticle help such plants survive the harsh climates? The cuticle prevents the water stored in the plant from evaporating in the air. The cuticle also acts as a shield that protects the plant from attack by germs and microorganisms.
There are endless strategies that plants adapt to survive in the desert. While most of these plants are generally small, they have the capability of surviving where even the largest plants on earth won’t survive. They have different ways of getting water and protecting themselves from the harsh environment.
While the desert environment may seem hostile and incapable of sustaining life, these plants have proven that they can survive and thrive in such climates. Some plants even survive by reducing competition around them. Such plants produce some chemicals that deter other plants from growing near them and competing for scarce water and nutrients.