Which of the following represents petiole?
A. 1
B. 2
C. 3
D. 4

Hint: Leaves belong to the shoot system in plants and are part of vegetative reproduction. The petiole is a small part of the leaf that connects the leaf base to the leaf lamina. The petiole is of different shapes and sizes and can show some modifications if required.

Complete answer: Morphology of a plant contains the root system, i.e. underground part of the plant and shoot system, i.e. part of a plant that is above the axis (above the ground). The root system comprises primary roots and secondary roots, while the shoot system in plants comprises flowers, fruits, stems, leaves, nodes (part from which leaves arises), and internodes (the part between the nodes). The root, stem, and leaves constitute the vegetative parts of the body, whereas fruits, flowers, and seeds constitute the reproductive system of the body. These plants undergo few modifications so that the plant can survive in adverse conditions like floods, drought, etc.

Leaves are an important part of the plant that perform photosynthesis and produce food for the plant. Leaves have three parts that are leaf base, petiole, and lamina. The leaf base is the part that attaches the leaf to the stem. Leaf lamina is a green-coloured expanded portion of the leaf. The petiole is a portion connecting the leaf lamina to the leaf base.
Hence, the correct answer is option D.

Note: Petiole can be modified into phyllodes. Phyllodes have axillary buds and do not have flowers. It plays an important role in respiration in plants. Some modified petioles can be edible, for E.g. Rhubarb, artichoke, and celery.