Question

Why does a cactus plant have fleshy leaves like photosynthetic stem?

Answer 1

• Cactus is a plant belonging to succulent xerophytic family. The plants belonging to this family follow a CAM pathway(Crassulacean Acid Metabolism) for transpiration . This means the transpiration doesn't occur during the day but at night.
• Like other plant, photosynthesis in cacti takes place in chloroplasts. Chloroplasts are the green pigments present in plastid of plants. Thus photosynthesis can be performed anywhere and everywhere the chloroplasts are present.
• But biology is all about the net /the bulk. Since the largest amount of chloroplasts are present in the leaves , they are the site of mainstream photosynthesis.
• But Cactus has no leaves . Its leaves are modified into spines, an adaptation to reduce transpiration.
• Thus the mainstream photosynthetic activity takes place in the stem of the cacti where relatively more amount of chloroplasts are present than the rest parts.