what kind of od modification desert plants use to stop willing
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Adaptations To Avoid Animals
Since desert plants are usually rare and have sparse populations, it is important for them to protect themselves against animals or other predators. As such, these plants have several adaptations that prevent animals from approaching them. Hunger and thirst draw animals to plants, but many desert plants have spines and thorns, such as the barrel cactus, that can harm an animal that attempts to eat it. Many of these plants are also toxic, such as the desert thorn-apple, and some are both spiny and toxic. Certain plants also use camouflage as a means to avoid being eaten by animals, such as the Arizona night-blooming cereus.
Drought Avoidance By CAM Photosynthesis
Plants usually absorb carbon dioxide during the day through stomata in their leaves to perform photosynthesis. However, openings of the stomata also lead to the loss of valuable water through evapotranspiration. Desert plants cannot afford to lose water, and therefore some plants perform Crassulacean acid metabolism (CAM) photosynthesis for carbon fixation. In CAM photosynthesis, stomata remain closed during the day but open at night to absorb carbon dioxide, which is then stored in the vacuoles as malate. During the day, malate is transported to chloroplasts, where its reconversion to carbon dioxide allows the remaining steps of photosynthesis to occur. Yuccas, xerophytic bromeliads, and epiphytic orchids are examples of plant species that perform CAM photosynthesis.
Leaf Adaptations In Desert Plants
Desert plants usually have leaves that are adapted to hot and arid conditions.
Size And Number Of Leaves
Desert plants have smaller leaves, seasonal leaves or no leaves at all. Species with small leaves, such as the little leaf palo verde tree or Parkinsonia microphylla, have less surface area on leaves and therefore lose less water through evapotranspiration. Plants like acacia and ocotillo, which are summer deciduous, drop their leaves during the hot season. As soon as weather conditions improve, these plants re-foliate. Additionally, plants such as cacti have spines or thorns instead of leaves, and photosynthesis occurs in stems or bark. Succulents like agave have fewer leaves that help them survive in dry environments.
Leaves With Specialized Stomata
Some plants have a limited number of stomata, while others have stomata that close during the day. Such adaptations allow plants to reduce water loss.
Leaves With Waxy Surfaces
Many desert plants have leaves covered in waxes or special oils that reduce transpiration. An example of such a plant is the creosote bush (Larrea tridentata).
Hairy Leaves
Some plants, such as the desert ironwood (Olneya tesota), have leaves with small hairs. These hairs reflect sunlight and block wind movement, both of which reduce evapotranspiration from the leaves.
Narrow And Pointed Leaves
Plants like the Joshua tree have narrow, pointed, and sharp leaves whose reduced surface area protects the plant against water loss.
Thick Leaves
Cacti and other succulents tend to have thick leaves with a large number of vacuoles that store wate. Such plants can survive for long periods of dry weather by using stored moisture content in their leaves.
Moving Leaves
The leaves of certain desert plants, like jojoba (Simmondsia chinensis), move throughout the day so that the Sun’s rays fall only on the edges of the leaves, reducing the heat transferred to the surface, which reduces evapotranspiration.
Stem Adaptations In Desert Plants
The stems of desert plants also exhibit various specializations that allow them to thrive in harsh desert climates.
Thick And Fleshy Stems
Stems of most cacti and other succulents are thick and fleshy. Such stems hold moisture that helps the plant survive drought.
Stems Have Waterproof Coatings Or Hairy Growths
Stems of desert plants also often have waxy coatings or hairy growths that help limit water loss and provide wind protection.
Root Adaptations In Desert Plants
Some Desert Plants Have Deep Roots
Desert plants like the mesquite have deep taproots that reach down to the water table to reach water. This root adaptation allows the plant to escape drought.
Fleshy Roots
The roots of plants that grow in arid conditions are often fleshy and thick, as the roots store moisture and nutrition, allowing the plant to survive dry conditions. These roots are called tubers.