Question

Which of the following is not a character of xerophytes?
A. Thick cuticle
B. Well-developed mechanical tissue
C. Well-developed conducting tissue
D. Spongy parenchyma

Answer 1

Hint: Plants which can survive in regions with very less water and moisture are known as xerophytes. These plants are generally found in desert, semi desert regions and even in arctic regions. These plants exhibit certain adaptations like reduced permeability in the epidermal layer, cuticle and stomata to retain water in their tissues.

Complete answer:
Xerophytes are plants found in regions that have very less water and moisture. Generally, they are found in desert and semi desert areas. These plants have adapted to their environment by certain changes in their physical structures like thickened cuticles, sunken stomata, long roots that go deep into the soil.

Xerophytes are known to secrete certain waxes and resins and develop thick cuticles that check evaporation of water. Shiny cuticles often reflect the rays of the sun and do not allow it to penetrate deep into the plant tissues thereby preventing excessive loss of water.

Xerophytes are exposed to winds, thus, the mechanical tissue in these plants are abundant and well developed. These tissues are composed of sclerenchyma or other lignified tissues in the stems. However, in roots large air cavities are present.

Xerophytes’ conducting tissues comprises the xylem and phloem. Xylem aids in transpiration. Xerophytes have woody xylem that help to maintain the water temperature in the plants. Otherwise the enzymes necessary for life processes will disintegrate resulting in the death of the plant. Phloem tissues help to transport water and minerals to different parts of the plant body that help the plant to survive.

Xerophytes are known to have palisade parenchyma at both surfaces of the leaves. The cells are thin walled with small intercellular spaces and are continuous with the stomata. This adaptation helps in the process of transpiration. Spongy parenchyma is absent or greatly reduced.

Therefore, option (D) is the correct option.

Note:
Xerophytes are plants found in the desert or dry regions. They are capable of withstanding dry weather conditions. They have developed certain physiological and structural enhancements to help them survive the extreme conditions. Xerophytes are of three types – Succulent perennials, non-succulent perennials and ephemerals.