Root modification

Introduction

Root modification refers to the changes in the structure of roots of plants to perform functions other than absorption and conduction of water and minerals. These modifications are generally in response to the plant's environment or specific needs. They are classified into two main types: modifications for food storage and modifications for special functions.

Modifications for Food Storage

Plants often modify their roots for the purpose of storing food. This food is typically in the form of starch, but can also include other nutrients. These modifications can be seen in a variety of plants, including both dicots and monocots.

Photograph of a taproot system in a dicot plant

Taproot Modifications

In dicots, the primary root or taproot and its branches can be modified for food storage. Examples of such modifications include:

Fusiform roots: These roots are swollen in the middle and tapering at both ends, resembling a spindle. An example of a plant with fusiform roots is the radish (Raphanus sativus).

Napiform roots: In these roots, the upper part is greatly swollen while the lower part is tapering. The beetroot (Beta vulgaris) is an example of a plant with napiform roots.

Conical roots: These roots are broad at the base and gradually taper towards the apex. The carrot (Daucus carota) is a plant with conical roots.

Adventitious Root Modifications

In monocots, the adventitious roots can be modified for food storage. Some examples include:

Tuberous roots: These roots are swollen and do not have a definite shape. Sweet potato (Ipomoea batatas) has tuberous roots.

Fasciculated roots: In these roots, a group of adventitious roots become swollen and form a fascicle or bundle. Dahlia is an example of a plant with fasciculated roots.

Modifications for Special Functions

In addition to food storage, roots can also be modified to perform special functions. These include:

Prop Roots

Prop roots provide additional support to the plant. They grow from the stem and penetrate the soil, providing stability. The banyan tree (Ficus bengalensis) is an example of a plant with prop roots.

Climbing Roots

Climbing roots help the plant to climb up the support. These roots arise from the nodes of the stem and attach to the support. The betel plant (Piper betle) and ivy (Hedera helix) are examples of plants with climbing roots.

Parasitic Roots

Parasitic roots are found in parasitic plants that derive their nutrients from the host plant. These roots penetrate the host plant and absorb nutrients. The mistletoe (Viscum album) is an example of a plant with parasitic roots.

Pneumatophores

Pneumatophores, also known as breathing roots, are found in plants growing in marshy areas. These roots grow upwards and help in the exchange of gases. The mangrove (Rhizophora) is an example of a plant with pneumatophores.

Conclusion

Root modification is a fascinating aspect of plant biology, showcasing the adaptability of plants to their environment. Whether it's for food storage or special functions, these modifications play a crucial role in the survival and success of many plant species.