How is cactus adapted to its habitat

In times of drought the body sinks in, or contracts. The most distinct part of a cactus is its spines. Because regular leaves don't conserve water well, the cactus developed these modified leaves to adapt to its extremely dry environment. The spines are better at conserving water and surviving in hot temperatures. Regular leaves provide a large surface area for evaporation of water to occur, the tiny spines do not.

The spines actually collect moisture from the air and let it drip down to the roots of the cactus. The prominence of ribs and flutes usually depends on how much water the stem is storing. When full, the ribs are almost invisible, but when the cactus is in a short supply of water, the stem shrinks and the ribs become quite visible. During the prolonged periods of a dry spell, other desert plants tend to drop their leaves and become dormant.

However, the cactus plant remains stable and unaffected since it has fixed spines instead of leaves. The green stem continues to photosynthesize while the waxy coating on the surface of the stem ensures that there is minimal water loss.

The dense network of spines provides shed to the stem of the plant, keeping it cooler than the surrounding air. Water is a basic need for any living organism. Without water, no plant or animal can survive on earth. But, where does the cactus plant find water to help it survive in the desert? Unlike the popular notion that deserts are dry throughout the year, the truth is that these places do experience sporadic rains. When the little rain falls, the cactus ensures that it absorbs as much water as possible.

The plant has adapted in a wide range of ways that help it to accumulate water. Another essential feature of cacti and other desert plants is that they tend to grow near riverbeds. Whether dry or wet, these areas tend to contain a significant amount of underground water that can help plants with deep roots survive the heat.

The primary function of the taproot is to allow the cactus to penetrate deeper into the subsurface soils that contain moisture. The taproot can extend up to five feet into the soil. This is the primary reason why some types of cacti, such as the Saguaro and the giant Mexican Cereus develop a long and strong taproot soon after germinating. Fog is another reliable source of water in deserts whenever the conditions are right for it. Air condenses to form dew that is captured by the cactus spines and hairs and directed to the ground where it is quickly absorbed by the roots.

The roots of the cactus plant are usually found near the surface and rarely go deep. A cactus plant can have a dense network of fibrous roots that spread out several meters away from the plant. Whenever it rains, the roots absorb as much water as possible and direct it to the stem region for storage.

The quantity of water stored will vary depending on the size and type of the cactus plant. In the famous Saguaro cactus, approximately to liters of water can be stored during a good rainfall season. When it rains, the cactus plant can easily shoot out more roots to ensure that there is maximum water absorption. However, during the drought season, the excess roots dry up and break off from the main plant to prevent water loss. Some types of cacti also have a modified root system that can store water and food.

This means that once the stem is full and there is still more water to be absorbed, the roots take up the water storage function. The other essential feature of the cactus that helps it to survive in deserts is the thick cuticle. Just like other succulent plants, cacti have a thick, waxy outer covering that is often referred to as cuticle.

In fact, on some cactus species, the cuticle can be thick enough such that you can easily scratch wax off the plant surface with your fingernail. The thick cuticle prevents water stored in the plant from evaporation into the atmosphere. It also protects the plant from germs and other microorganisms that may try to attack it from the surface. The primary purpose of stomata is to let in carbon dioxide that helps the plant to manufacture food.

When the stomata open, water vapor escapes from the plant into the atmosphere. Typically, the stomata open during the day and close at night. To minimize water loss through the opening of stomata, cacti experience reversed opening and closing of the stomata. This means that the stomata close during the day and open at night. Areoles are plant structures unique to cacti. They usually appear as woolly or hairy areas on the stem from which spines emerge.

Separation of Substances. Changes Around Us. Getting to Know Plants. Body Movements. The Living Organisms — Characteristics and Habitats. Motion and Measurement of Distances. Light, Shadows and Reflections. Electricity and Circuits.

Fun with Magnets. Air Around Us. Garbage In, Garbage Out. A shallow root system allows cacti to absorb as much water as possible when it rains, as well as providing access to small amounts of moisture that may occur at the surface due to fog, mist, or morning dew. Another interesting way cactus roots harness precious water and prevent water loss is by sprouting temporary root hairs when it rains.

Then, after the soil dries out and they are no longer needed, the root hairs die away. This prevents water loss back into the soil and saves the plant from having to use its energy to maintain them. One of the most striking cactus adaptations is their lack of leaves. Although not all cacti are leafless, the species with leaves are limited to a small number of cacti belonging to three groups of quite unusual cacti: the genera Pereskia and Maihuenia and the subfamily Opuntioideae.

A plant pore is called a stoma, and multiple pores are called stomata. The flat shape of common, non-succulent leaves maximizes their exposure to sunlight by providing a large amount of surface area compared to how much internal tissue they have.

This large surface area also means that leaves have a lot of stomata. The problem for plants trying to survive in hot, arid climates, where water evaporates quickly, is that when their stomata open to facilitate photosynthesis, water vapor escapes.

So desert cacti have addressed this water loss by eliminating leaves altogether and moving the job of conducting photosynthesis to their thick stems, where the exposure to the atmosphere of tissues holding the water needed for photosynthesis is minimized.

And the reason for this change is, once again, to minimize the loss of moisture through stomata. CAM photosynthesis allows the plant to open its stomata at night, when temperatures are cooler and the evaporation rate of water is lower. The plant stores the carbon dioxide it takes up in the form of malic acid, so that during daylight hours, it can carry out photosynthesis with the stored carbon dioxide and the stomata can remain closed. When it comes to cactus adaptations, the stems have developed a number rather ingenious ways to adapt to harsh arid climates.

They use their unique inner cell structures and features on their outer surfaces to store and preserve water.

The cortical layer, or cortex, of a plant stem is the area just inside the outer layer of cells known as the epidermis, and the cortical layer of cacti is unique among plants in having an inner region that serves as a water reservoir, where walls of the water-holding cells are thin and flexible.

These large cells fill up with water for storage and then release it to the cells that need it in times of drought. Additionally, in many types of cacti, these special cortical cell walls are undulating rather than smooth, so the cells can collapse in on themselves and release the water more efficiently. These water-storage cells in the stems of cacti are filled with mucilage, the gooey substance found in many succulent plants that is very good at binding water and preventing it from evaporating.

In cacti, these mucilage cells are often aligned into canals. Cacti also have thicker cortical layers than any other plants. And this cortical layer further differs from the cortex of other types of succulents in its ability to transfer water and plant sugars produced by photosynthesis due to vascular tissue that is distributed throughout it.

This efficiency in transference is what allows cactus stems to become so large in diameter and thus store larger volumes of water. Then, when the air cools down at night, the internal heat slowly radiates back out but keeps the tissue from freezing on cold winter nights.