Question

Select the correct statement:
I. From the region of elongation, some of the epidermal cells form root hairs
II. Pneumatophores are seen in Sonneratia
III. Adventitious roots are seen in banyan tree
IV. Maize and sugarcane have prop roots

• A. I and IV
• B. I, III and IV
• C. III and IV
• D. II and III

Answer 1

The correct option is D II and III

The roots in a plant arise from the radicle of the embryo and have four distinct regions - root cap, region of meristematic activity, region of elongation and region of maturation. Each part has its own characteristic feature. The region of elongation undergoes rapid elongation and enlargement and hence, is responsible for the growth of root in length. The region of maturation gives off some very fine, delicate, thread-like structures, called the root hairs, that are formed from some of the epidermal cells in the region of maturation. They help in absorption of water and minerals.

Pneumatophores or respiratory roots are seen in halophytes or plants that grow in areas having high salt content. Sonneratia, Heritiera are examples of halophytes that grow in swamps and salt lakes. As the soil is water-logged in swamps, the space between the sediment grains is filled with water instead of air. Hence, the oxygen levels are lower in the soil than the air. The respiratory roots rise vertically upwards to get oxygen for respiration.

Adventitious roots are the roots that arise from parts of the plant other than the radicle. There can be several modifications of the adventitious roots - storage roots (sweet potato), prop roots (banyan tree), stilt roots (sugarcane and maize). Prop roots arise from the branches and grow vertically downwards like pillars to support the plant. Stilt roots arise obliquely from lower nodes of the stem and support the plant like ropes of a tent.