36. Describe various stem modifications associated with food storage climbing and protection.


The various stem modifications are as follows


 Modification of Stem for Storage of Food


In this case the stem becomes underground and grows horizontally, stores food material. It bears nodes, internodes and buds which give rise to aerial shoots, e.g., ginger, banana, turmeric.


Stem is underground, grows vertically and bears nodes as well as internodes e.g. Colocasia.


In this case, the stem becomes underground,the internode is shortened in such a way that the leaves are condensed and these leaves become thick and fleshy and store food e.g.,onion.


This is also a special kind of stem modification, which arises at the tips of special narrow underground branches. They have nodes, internodes apical buds, scale leaf in the form of ridge. They gave no. of eyes which represent nodes. It is meant for storing food material, e.g., potato

Stem tendrils

Modification of Stems for Climbing These are found in cucurbits and grapevine. The axillary buds of the stem become elongated and spirally coiled and twine around a support for the plant to grow as the stem is weak and herbaceous.

Stem thorns

Modification of Stem for Protection These are present in the axil of leaf Or apex of stem performing the function of either climbing or defence, e.g., Duranta, Calamus and also reduce transpiration.