Describe modifications of the stem for specific functions.

(N/A) The stem performs several functions in addition to its primary roles of support and conduction. It undergoes modifications to adapt to these specific functions:
$(A)$ Modification of stems for food storage:
$(i)$ Rhizome: Plants like ginger,turmeric,and Canna have underground stems that grow horizontally. They store food,possess distinct nodes and internodes,and bear scaly leaves and adventitious roots.
$(ii)$ Tuber: In potato,the tips of underground branches swell due to the accumulation of food,forming a tuber. The surface of the tuber has depressions called 'eyes',which represent nodes and contain axillary buds that facilitate vegetative propagation.
$(iii)$ Corm: Amorphophallus (suran) and Colocasia have a condensed,vertically growing underground stem known as a corm,which stores food.
$(B)$ Modifications of stem for climbing:
Stem tendrils develop from axillary buds in plants like gourds (cucumber,pumpkins,watermelon) and grapevines. These are slender,spirally coiled structures that help plants climb.
$(C)$ Modifications of stem for protection:
Axillary buds of the stem may get modified into woody,straight,and pointed thorns in plants like Citrus and Bougainvillea,protecting them from browsing animals.