Question

Cladode is the modification of
A. Leaf
B. Root
C. Petiole
D. Stem

Answer 1

Hint: Modification refers to the change in the organs to perform special functions. The changed organs are known as modified organs. Moreover, all the parts of the plants like stems, leaves, flowers, etc. show various types of modifications according to the different needs.

Complete step-by-step answer:
The cladode is the aerial modification of the stem. Aerial modification means that it is formed from that part of the stem that always remains above the soil in the air. Cladodes are the short, fleshy, and green stems that have single internodes. Cladodes originate from the main stem as branches. Cladode looks like leaves but they are stems. They are used for the storage of food.
A very common example of aerial stem modified to form the cladode in Asparagus. Asparagus has very reduced leaves that are modified into thorns.
Thus, based on the above information we can conclude that the cladode is the modification of the stem.

Hence, the correct answer is an option (D).

Additional Information:
Some aerial modifications of the stem are as follows –
Stem tendrils – In some plants, the axillary bud is modified into thread-like sensitive structures that are known as the stem tendrils. The tendrils help in the climbing of the plant. They are commonly found in cucurbits and grapes.
Thorn – In some plants, the axillary bud restricts the growth and they are modified into the hard pointed structures known as the thorn. They are commonly found in citrus, carissa, and Duranta.
Phylloclade – When the stem becomes flat, fleshy, and green then it is known as the phylloclade. The functions of the leaves are performed by the stem in the phylloclade. The stem has water and food stored in it. The leaves are modified into the spine to prevent the loss of the water and to protect them from the prey. A very common example is the Opuntia.

Note : Apart from aerial modifications, the stem also shows underground modifications and sub-aerial modifications. In an underground modification, the underground parts of the stem are modified to perform special functions of food storage and multiplication. In a sub-aerial modification, some part of the stem is outside the soil in the air and some part is inside the soil. It is mainly a modification for the purpose of vegetative propagation.