question_answer 51)

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

Answer:

                  The various stem modifications are as follows    

Stem	Modification of Stem for Storage of Food
Rhizome	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		Modification of Stem for Storage of Food
Corm		Stem is underground, grows vertically and bears nodes as well as internodes e.g. Colocasia.
Bulb		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 material e.g.,-onion.
Tuber		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.
		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, .g., Duranta, Calamus and also reduce transpiration.