Question

In which plants stem are modified to store food and also act as an organ of perennation to tide over conditions unfavourable for growth?
A. Turmeric and Cucumber
B. Chrysanthemum and Ginger
C. Turmeric and Potato
D. Euphorbia and Sweet Potato

Answer 1

Hint: Modified stems are of various types such as- rhizomes, corm, tubers, bulb, etc. These stems are helpful in the storage of food for the plant when adverse conditions are faced by it. The plant uses stored nutrients to survive those conditions and later germinates after favourable conditions are met. Swollen tubers and rhizomes are the main storage organs that are used by the plants to perennate and store food.

Complete answer:
-Turmeric’s stem is known as “Rhizome”. They are modified stems that grow parallel to the ground and shoots and roots grow out with the help of nodes perpendicularly.
-“Creeping Rootstalks” is also a name given to rhizomes.
-Perennation is a term used for plants that can store food and nutrients to survive the unfavourable conditions and skip the germination process during those unfavourable conditions. Although when favourable conditions are met by the plant, the organism germinates by the help of a perennating organ. Hence perennation is a type of vegetative reproduction because the new plant grows from a part of the parent plant.
-Potatoes, on the other hand, are underground stems, known as “Tubers”. Tubers also function as the storage room for potatoes. They store food for the subsequent growth of the plant. The tuber is a modified stem because it contains nodes (called eyes) and internodes (the space between the eyes). Tubers in potatoes develop at the end of the rhizome, the modified stem in potatoes just like Turmeric. The eyes of tubers contain axillary buds which can expand to grow into a whole new plant.
-A potato plant, mostly during the winter season, does not germinate and drops off the green parts, to survive the cold climate. When spring arrives, the buds (eyes) expand and germinate, from which a whole new potato plant may arise and flower.
-Cucumber on the other hand has modified leaves known as “Tendrils” which help them to climb over the ground vertically.
-Chrysanthemum mainly propagates through “suckers” which grow from the main stem of the plant and bury underground to some distance horizontally to the surface. From there, they grow shoots and roots perpendicular to the ground.
-Euphorbia has modified its stem as a fleshy cylindrical, flattened stem. They are green in colour as they contain chlorophyll and carry out the process of photosynthesis. These plants also propagate vegetatively by stems.
Sweet potato has modified its roots rather than shoots or stems. The tubers arise from the roots and hence are different from potato tubers.

Hence, the correct answer is option (C).

Note: As discussed before, the turmeric plant has modified the stems to store the food, known as “Rhizome”. A plant modifies its stems, roots or even leaves according to their needs. For example-
Modification of leaves are- tendrils (to climb and support the plant, example- grapevine), succulents (to store water inside the leaves, example- jade plant), Onion has modified the leaves to store the nutrients. Petals of the flower are also a modification of the leaves to protect the flower.
-Modification of stem- Presence of thorns on stems serve for protection from grazing plants (rose plant), Formation of tendrils for the plants that have weak stems to support the plant over support (cucumber), for storage purposes, plants can form structures like rhizomes, bulbs, tuber (potato), corn to help the plant survive the unfavourable conditions.
-Modification of roots- formation of taproot or adventitious roots for storage or propagation purposes (radish and carrot); adventitious roots can be found in Dahlia, Asparagus, etc. Furthermore, aerial roots can be found for better air exchange between the plant and the environment and to support the plant. The biggest example for the same is the Banyan Tree. Parasitic plants develop suckers to absorb nutrients from their host, example- Cuscuta.