$\rightarrow$ Stem performs some extra functions in addition to its normal functions. It gets modified for these functions.

$(A)$ Modification of stems for food Storage :

$(i)$ Rhizome : Ginger, Turmeric, Zaminkand, Colocasia are underground stems. They store food and become an irregularly shaped node. It possesses nodes, internodes, scaly leaves and adventitious roots.

$(ii)$ Tuber : In potato, scaly leaves located on underground stem, arise from axil of branches at top store food and forms round or oval structure. It is called tuber. There are craters on the surface, of potato, it is called eye. It has bud. That performs vegetative propagations.

(iii) Corm : Amorphophalus is a condensed form of Rhizome.

$(B)$ Modifications of Stem for Climbing :

$\rightarrow$ Stem tendrils : In Passion Flower, Cucurbit, Bitter Gourd, Gourd, Cucumber stem tendrils develop as axillary buds are slender and spirally coiled and help plants to climb. Such plants are called tendullar plants.