Read this article to learn about the different types of modification of roots !
A. Modified Tap Roots
1. Fusiform Tap Root:
It is swollen in the middle but tapers gradually towards the two ends, e.g., radish.
2. Conical Tap Root:
It is swollen at the base but tapers gradually towards the apex, e.g., carrot.
3. Napiform Tap Root:
It is very thick and almost globular at the base and abruptly points towards the apex, e.g., turnip and beet.
B. Modified Adventitious Roots
1. Fibrous Roots:
They may be thin, slender or thread like, as in wheat and grass.
2. Prop Roots:
They arise from the underside of the branch and grow vertically to reach the soil they serve both for the absorption of water and for supporting the spreading branches of the stem, e.g., banyan.
3. Buttress Roots:
These roots grow partly above the ground and look like buttresses, e.g… Silk- cotton tree (symbol)
4. Stilt Roots: They arise from all sides of the stem at the nodes, a little above the ground. They fix the plant in the soil like the ropes of a tent. e.g… Sugarcane and maize
5. Tuberous Roots:
These roots become thick, and swollen due to the storage of food material, e.g., Asparagus, sweet potato. In some orchids and Dahalia, the tubers are branched and are called palmate.
6. Climbing Roots:
They develop from weak stems in climbing plants and arise from nodes, e.g., pathos and ivy.
7. Parasitic Roots (Haustoria):
They arise from stems and grow on other plants called the host- plant. These roots penetrate into the tissues of the host-plant and establish connection with phloem and thus absorb food and water from it, e.g., Cuscuta.
8. Epiphytic Roots:
They are the roots of epiphytic plants (plants which grow on other plants without deriving any benefit from them). These roots remain suspended in air and never touch the ground. They are hygroscopic in nature and absorb moisture from atmosphere through spongy tissues called velamen, e.g., orchids.
9. Aquatic Roots:
These roots are not fixed to the soil or substratum and remain floating in water. They are unbranched without root-hairs and root-cap, e.g., lotus and water-hyacinth.
They are breathing roots in plants which grow in marshy places and cannot obtain sufficient 02 for respiration. They grow erect vertically upwards in air from the underground part of the plant and collect air from the atmosphere through lenticels (pneumathodes), e.g., Rhizophora and Bengali Sundri (which has given the name of the Sunderbans).
(1) Rootless plants, e.g., Wolffia and Epipogium.
(2) Plants that are all roots, e.g., Podostemon plant is a thalloid assimilatory root and Monotropa which produces only a free- living root on germination.