Rain forests and even Canada’s far north are home to cacti. However, their most amazing characteristic is their capacity to flourish in the desert, where rain occurs sporadically and erratically.
By working evenings, finding alternate ways to get energy, and maintaining a bag of sour tricks.
The cactus have developed a wide range of adaptations to live in the desert, according to Erika Edwards, a plant evolutionary researcher.
The saguaro, or Carnegiea gigantea, is one of the most recognisable cacti. However, they only flourish in the Sonoran Desert, where they can be seen growing tall in a small area of southern Arizona, northern Mexico, and southeastern California.
According to research by Edwards and Michael Donoghue of Yale University, leafy shrubs and trees of the Pereskia genus originally exhibited some of these water-saving characteristics over 20 million years ago.
The journal American Naturalist reported the findings in its June issue.
Stomata are tiny skin pores that open and close on all plants to capture carbon dioxide. Plants convert the carbon dioxide they have gathered into nourishment in the form of carbohydrates during photosynthesis. Water escapes from the pores every time they open, making the process challenging in the desert.
It’s hazardous business to open the pores and lose water if you’re attempting to conserve water, Edwards told LiveScience.
Cacti and other nocturnal plants, including agaves and aloes, open their pores at night while most plants open their stomata during the day.
Cacti are able to hold onto water because of the cooler temperatures, lack of sunlight, and quieter breezes.
In order to thrive in their harsh environments, cacti have also evolved succulent tissue, waxy skin, prickly spines, and a unique root system.
- The stem serves as a reservoir, and depending on how much water it contains, the plant will grow and shrink.
- The waxy layer of the skin keeps moisture in.
- The sharp spines defend against animals asking for a free sip out of thirst.
Some cacti have spines that also catch raindrops and deliver the valuable liquid to the plant’s roots.
You might imagine that cactus would develop extensive root systems to look for a steady source of groundwater. Instead, they frequently form large, shallow root systems that reach several feet away from the plant, sit just below the Earth’s surface, and are ready to collect as much water as possible.
Cacti grow additional roots when it rains. To conserve the plant’s water supply during dry times, roots will shrink and split off.
According to Edwards, “the cactus becomes more hydrated than the soil it is growing in.” It must cut its connection to the soil since it faces the risk of losing water to the soil.
Even lacking the morphological peculiarities of the typical leafless cacti, leafy cacti like the Pereskia and other plants have evolved comparable water-saving features and reside in the desert.
It’s solid proof that the tactic is effective, according to Edwards. “The plants thrive very well in these conditions.”
How does a desert cactus plant survive without water?
It does not, however, totally survive without water. Every living thing needs water, yet cacti are specifically built to thrive in dry environments and make better use of the water they do receive than other plants. It doesn’t lose its water through evaporation as quickly as other plants do since it lacks leaves. Its stems are robust, offering plenty of space for storing water and a lid that keeps the water within. Some cactus species may survive without water for two years. Depending on the species, the indoor types do need to be watered more frequently.
A cactus plant’s survival strategy
A cactus may endure in the desert because it has the following characteristics: I It has lengthy roots that bury themselves deeply in the ground to capture water. (ii) In order to reduce water loss through transpiration, the leaves have spines. (iii) To hold onto water, the stem of the plant is wrapped in a thick waxy covering.
How does cactus withstand intense heat?
Climate change is nothing new. The species on earth have experienced the “Climate change since the beginning of life on Earth more than 3 billion years ago has posed the “cope, adapt, or die” dilemma.
Some species already survive in harsh environments (a subject I covered in my previous blog post) at the earth’s freezing poles during the winter, at the summit of tropical mountain peaks that receive tens of metres of rainfall annually, and deep within the dry deserts that make up a third of the planet’s land area.
In particular, when the creatures are unable to climb to a cooler elevation or slither into a deeper riverine pool to avoid a heat wave, the plants and animals that can survive these harsh conditions may be able to tell us something about adapting to climate change.
Plants typically live their entire lives anchored to one location on the soil. They must therefore be capable of withstanding whatever the weather may be like 365 days out of the year.
The prickly cholla cactus is one example of a plant from a scorching desert that has developed a wide variety of outstanding coping mechanisms to survive in North America’s hottest, driest climate, where an entire year’s worth of rainfall can fall in a single extreme event.
Our understanding of the biological and physical adaptations that allow for survival on a hotter, drier world that is prone to extreme events is greatly aided by these desert dwellers (as climate change experts are currently forecasting).
The world’s oldest tree, a Great Basin bristlecone pine (Pinus longaeva) that is between 5,062 and 5,063 years old, as well as fascinating secrets to longevity can be found in desert plants “Creosote bush (Larrea tridentata) King Clone is the oldest known clonal colony and is thought to be 11,700 years old.
The ancient creosote clone is particularly fascinating from the standpoint of climate change and adaptation because the environment in which it first emerged (at the end of the last ice age) was different from the one in which it now exists.
Well, plants defend themselves against extreme heat by developing smaller leaves (cactus spikes), using water-saving photosynthesis techniques (like Crassulacean acid metabolism), developing sun-blocking hairs, or developing thin leaves that can easily cool in a breeze or waxy leaves that stop water loss.
They can also do this by generating exceptionally long, quick-growing roots that can swiftly access groundwater or short roots that extend when it rains.
Cacti have flexible features that enable the expansion of their stems and the storage of additional water for usage when it is not raining. Last but not least, plants have developed the capacity to postpone germination and growth in order to coincide with periods of water availability and comfortable temperatures. This prevents the exposure of vulnerable young seedlings to the worst conditions.
These adaptations are excellent, but why should I care? you might be asking.
In addition to their natural beauty and sustenance of other desert species, plants bring practical advantages to mankind. In order to solve human issues, scientists and engineers have started to emulate the tactics used by animals and plants in nature.
As we work to adapt to a hotter, drier planet, desert plants may be especially useful resources. If we preserve their natural environments, we’ll have the best opportunity of understanding what they have to teach us.
Wikipedia: How does a cactus endure in the desert?
Because it grows in dry environments, cacti don’t have leaves. Water can be wasted when leaves transpire. By not having leaves, the cactus conserves water. The cactus’ stems are what are green on the plant.
What three adaptations do cacti have?
Sunlight is reflected by white, thick spines. Spines offer cover! The fleshy, thick stem of cacti may hold a lot of water. To assist the cacti retain water, the stem possesses a waxy waterproof coating.
How do desert cacti obtain water?
Despite being notorious for being dry and dusty, desert regions occasionally get rain. In order to assist them absorb as much water as possible, cactus plants grow roots that are a few inches below the surface of the soil. Their shallow and dispersed roots allow plants to absorb water from even light showers.
Additionally, these plants produce some auxiliary roots that take up extra water on days when it rains. When it rains, these roots can emerge from the cacti in just two hours. As soon as they sprout, they start to work. The temporary roots separate from the main roots when it stops raining in order to minimise water loss.
The main plant receives the water that can be absorbed by all of the roots and stores it there. During the wet seasons, some giant cacti plants, like the saguaro cactus, may store up to 4200 pounds of water. Until it rains again in a few seasons, they can get by on this water.
Other cacti species develop taproots, which are extremely lengthy roots. The plant can withstand the protracted drought by drawing moisture from the soil through its deep subterranean roots. Additionally, the taproot makes sure the plant has a solid foundation so it won’t be swept away by rainstorms or soil erosion. Saguaro and Mexican cereus are two cacti that can grow taproots.
Some cacti have succulent roots that store food and water in addition to the roots that aid the cactus in absorbing water. The Cereus greggii, often known as the Arizona queen of the night, is an illustration of one such cactus. To function as storage, these cacti plants have larger roots. These plants have roots that can extend up to 27 kilometres. The xylem tissue refers to the expanded areas of these roots.
Other cacti plants isolate themselves from the ground to reduce water loss. This is due to the fact that the plant may occasionally have more moisture than the soil, causing it to run the risk of losing water to the ground.
Cacti lack aerial or rambunctious roots because these root types frequently promote water loss.
Cacti and camels both live in the desert, but how?
Camels are ideally suited for desert survival. Their modifications consist of:
- to spread their weight out on the sand, they have large, flat feet.
- Thin fur elsewhere to allow for rapid heat loss and dense fur on the top of the body for shading
- a high surface-to-volume ratio, which will increase heat loss
- the capacity to continue for a long time without water because they urinate and sweat very little.
- being able to withstand body temperatures of up to 42C
- two rows of eyelashes and slit-like nostrils to help keep sand out.
How does a cactus produce its food?
Like all plants, cacti prepare their food through the process of photosynthesis. Since the leaves of cacti are essentially reduced to spines, photosynthesis occurs through the stem. Chlorophyll makes the stems green so that the plant can produce food from them.
How do plants survive in the desert?
Desert plants may have a completely different appearance from regional native plants. They frequently have inflated, spiky, and small, rarely bright green, leaves. Their impressive adjustments to the difficulties of the desert climate are the cause of their peculiar look. The only characteristic that distinguishes a desert and the main constraint to which desert species must adapt is aridity.
This pink fairy duster’s tiny leaves are an example of a reduced leaf surface area, which increases the plant’s water efficiency.
Succulence, drought tolerance, and drought avoidance are the three main adaptive mechanisms that desert plants have developed. These are all distinct but useful sets of adaptations for thriving in environments where plants from other places would perish.
Succulence
In their soft leaves, stems, or roots, succulent plants store water. All cacti, as well as non-cactus desert residents including agave, aloe, elephant trees, and numerous euphorbias, are succulents. The water storing habit cannot function without a number of additional adjustments.
Agave victoriae-reginae is an example of a succulent plant that stores water in its leaf blades. They are CAM plants (see below), which means they use very little water, and they also have waxy cuticles.
A succulent needs to have the capacity to absorb a lot of water quickly. Desert rainfall are frequently modest and fleeting, and the hot sun causes the soil to dry out quickly. Nearly all succulents have vast, shallow root systems to adapt to these environments. Saguaro plants have roots that reach horizontally nearly as far as their height, but they are rarely deeper than four inches (10 cm). The majority of the water-absorbing roots are located in the top half-inch (1.3 cm).
Succulents need to be able to use their water reserves as well as possible in a drying climate. Most species’ stems and leaves have waxy cuticles that, when the stomates are closed, make them practically impermeable. Reduced surface areas further conserve water; most succulents have few leaves (agaves), none (most cacti), or deciduous leaves during dry seasons (elephant trees, ocotillos, boojums).
A water-efficient form of photosynthesis known as CAM, or Crassulacean Acid Metabolism, is found in many succulents as well as semi-succulent plants like most yuccas, epiphytic orchids, and xerophytic bromeliads. CAM plants store carbon dioxide and open their stomates for gas exchange at night. The stored carbon dioxide is used for photosynthesis during the day, when the stomates are closed. In comparison to conventional C3 plants, CAM plants lose one-tenth as much water per unit of carbohydrate produced at night because of the lower temperatures and higher humidity.
This prickly pear cactus uses its spines to defend itself from hungry predators in addition to storing water in its succulent pads (stems). Spines also aid in shading the plant and directing and capturing moisture.
The ability of CAM plants to maintain an idle metabolism during droughts is another advantageous quality. Stomates in CAM plants remain closed day and night when they are under water stress, which virtually stops gas exchange and water loss. However, the plant keeps its metabolism at a low level in the moist tissues. An idle CAM plant can restart full growth 24 to 48 hours after a rain, just like an engine can accelerate to full speed more quickly than one that is cold. Succulents can so quickly benefit from transient surface wetness.
In a dry area, stored water needs to be protected against creatures who are thirsty. Most succulent plants are poisonous or prickly, and frequently both. Some species defend themselves by only growing in remote areas. Others still use concealment. For instance, the dry stems of the plants it grows in closely resemble the Arizona night blooming cereus.
Drought Tolerance
A plant’s capacity to survive desiccation without perishing is referred to as drought tolerance (or drought dormancy). During dry spells, plants in this group frequently lose their leaves and go into a profound slumber. Dropping leaves conserves water in the stems since transpiration through leaf surfaces accounts for the majority of water loss. Some plants with resinous coatings that prevent water loss do not typically lose their leaves (e.g., creosote bush).
The resinous layer on creosote leaves prevents water loss. To conserve water and withstand extreme temperatures, these leaves have made adaptations.
Compared to plants in wetter areas, drought-tolerant shrubs and trees have broad roots that can extend up to twice as wide as the canopy. They penetrate the soil more deeply than the roots of succulents, and occasionally they reach very deep levels (e.g., mesquite). However, the majority of a mesquite’s roots are found three feet (0.9 m) or less below the ground.
Growth cycle opportunities are controlled by rooting depth. Contrary to succulents’ shallow-rooted technique, shrubs and trees need a significant amount of rain to saturate their deeper root zones. It takes a few weeks for plants like brittlebush and creosote to emerge from deep slumber after a heavy rain. The disadvantage of this method compared to that of succulents is that, after receiving multiple showers, the deeper soil retains moisture for a considerably longer period of time than the upper layer, allowing for several weeks of growth.
Only when the earth is almost completely saturated can succulents absorb water. Conversely, drought-tolerant plants may take up water from considerably drier soil. The same low leaf moisture contents that would be lethal to most plants allow these plants to photosynthesize.
Grey leaves of brittlebush deflect sunlight and help the plant to stay a little cooler. Additionally, they shed leaves easily during dry spells and soon begin to leaf out following rain.
Drought Avoidance
By not existing, annual plants avoid harsh circumstances. They grow to maturity in a single season and then perish after using all of their life force to produce seeds rather than saving any for future survival.
The majority of Sonoran Desert annuals only have a brief window in the fall, after summer heat has subsided and before the onset of winter cold. For the majority of species, there must be a drenching rain of at least one inch during this window of opportunity. An inch of rain in the mild fall weather will give enough soil moisture to ensure that seeds will likely grow and produce seeds even if nearly no further rain falls during that season. This combination of conditions is survival insurance. There is still further protection because not all seeds will germinate, even in ideal circumstances; some will remain dormant. A portion of the desert lupine seeds produced each year do not germinate until they are 10 years old, yet the mechanisms underlying this phenomenon are unknown.
These Arizona poppy and lupine wildflowers are waiting for the ideal conditions. Autumn and winter rains are when spring bloomers germinate. Before the summer heat and dry weather arrive, they will bloom in the spring, then go to seed and eventually die.
During the pleasant fall season, seedlings quickly create rosettes of leaves, rest flat against the ground over the winter as they grow more slowly, then bloom in the spring. Many people believe that spring rains are the cause of our wildflower displays because plants are barely noticeable until they start the spring bolt.
Only in communities with dry seasons are annuals prevalent because perennial plants need a certain amount of root space to acquire enough moisture to survive the driest years. A population of quickly developing annuals can take advantage of both open space and moisture in the rarer rainy years. The fraction of annual species increases with habitat aridity. The Sonoran Desert’s vegetation is made up of annual species to a certain extent. Up to 90% of the plants in the driest ecosystems are annuals.
Although the desert may appear hostile, this is only the perspective of an outsider. Native plants and animals are able to thrive here most of the time thanks to adaptations.
Did you realise that up to 70% of water use takes place outside? Because of this, we adore desert flora and regularly highlight them. For advice on selecting plants and planting them correctly, visit our page on Choosing and Planting Low Water-Use Plants. Please read all of our featured Plant of the Month blogs as well!
With permission, this piece is being reproduced. The original article can be read here. WaterUse It Wisely occasionally hosts guest bloggers who discuss issues relating to water and water conservation. Mark A. Dimmitt, the writer of this blog entry, formerly served as the Arizona-Sonoran Desert Museum’s curator of natural history. The Arizona-Sonoran Desert Museum was established in 1952 with the goal of encouraging people to love, appreciate, and comprehend the Sonoran Desert in order to live in harmony with the natural world. Zoo, botanical garden, art gallery, natural history museum, and aquarium are all included in the museum’s fusion experience.