Q. Which of the following leaf modifications occur (s) in the desert areas to inhibit water loss?

  1. Hard and waxy leaves
  2. Tiny leaves
  3. Thorns instead of leaves

Select the correct answer using the code given below:

  • 2 and 3 only
  • 2 only
  • 3 only
  • 1, 2 and 3

Answer: (d) 1, 2 and 3

Notes:

  • There are some plants that grow in extremely dry conditions throughout the year.
  • Structural adaptations are important to plant survival in the desert.
  • For this purpose, they undergo some morphological adaptations in the xerophyte stem.
  • These are as follows:
    • The stems of woody xerophytes are comparatively stunted, hard, and rigid. They may be covered with thick bark. e.g. Acacia arabica.
    • Wax coatings on leaves prevent water loss through evaporation because the loss of water from both the surface and the inside of leaves occurs in the hot desert.
    • The stem is covered by hairs or waxy coating.
    • The main stem and branches may occur thick, fleshy, flattened, and have a green modified structure called phylloclade.
    • Leaves are also smaller on desert plants, further reducing the possibility of water loss.
    • Phylloclades are found in succulent xerophytes. They do photosynthesis. e.g. Opuntia, Cacti etc.
    • Usually, in phylloclade bearing xerophytes, leaves are modified into spines that are known to check the rate of transpiration.
    • They have hard, thick coatings and some are covered in prickly spines to prevent water loss.
    • It is to protect them from animals who might try to chew through them to get to their moisture.
    • The stem may occur as an underground modified structure to store food and takes part in reproduction. e.g. Saccharum.
xerophytes