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The Stages That Desert Plants Go Through in Photosynthesis

Standard photosynthesis involves the transferring of sunlight and water into glucose sugars through the chloroplasts and chlorophyll in the plants cells. This food is then broken down and transported to the different parts of the plant allowing it to grow. Due to a lack of water and the naturally harsh conditions in desert regions plants, such as cacti, have altered how they photosynthesize, although the basic process is identical.

Leaves
- Plants that live in temperate or tropical conditions tend to have large leaves situated toward the top of the plant. This is because this is the best way for the leaves to absorb the maximum amount of sunlight. In the desert there is too much sunlight for plants to grow so the plants growing there have smaller leaves and grow closer to the ground as there is no risk of a lack of sunshine.
Roots
- In areas where there is a steady supply of rainfall the water table under the soil is higher than in the desert where there is little or no rainfall. Plants where there is a constant supply of water have shallower roots as there is no need to search for water. In the desert plants have very deep roots so they have access to hydration even if the water table is 10 or 20 meters below the surface.
Stems
- Plants in the desert, like cacti, are famous for storing water in its trunk so it can be used later. Temperate and tropical plants do not have this problem and have developed thinner stems compared to those plants living in arid conditions.
C4 Photosynthesis
- Standard photosynthesis is called C3 as the absorbed carbon dioxide is incorporated into a 3-carbon compound. Plants like salt bushes and summer blooming varieties use C4 photosynthesis which turns the carbon dioxide in a 4-carbon compound. The plants use the same enzyme for photosynthesis as other plants, rubisco, but the photosynthesis takes place deep within the plant rather than in the leaves. This is because if the process took place in desert plant leaves the limited water available would evaporate too quickly. The high light-intensity and temperature allows photosynthesis to happen quicker so less oxygen is collected. This means there is less waste and so the plant perspires less allowing it to use less water.
CAM Photosynthesis
- CAM, or Crassulacean Acid Metabolism, is a process used by cacti. Carbon dioxide is collected through the cacti's pores during the night so there is less evaporation. During the day the carbon dioxide is converted into an acid, broken down with the sunlight to create the rubisco enzyme. CAM plants are also able to stop photosynthesis during particularly arid times. When there is a lack of sunlight or water moist plants loose leaves and twigs. Cacti turn the photosynthesis process off, absorbing no carbon dioxide. The cacti's cells then work like perpetual motion with the oxygen waste from photosynthesis being used for respiration and the carbon dioxide given off in reparation reabsorbed for photosynthesis.

Nature