Modification of stem

Modification of stem

Modification Of Roots -

1. Underground modification

2. Sub-aerial modification

3. Aerial Modification

1. Underground modification

1.Tuber -

It is branch of stem which stores food and swell up and forms tuber .

This tiber have always axillary buds (eyes) on the surface.

These buds are capable to grow into new plants under favorable conditions. eg , potato (solenum tuberosum).

2. Rhizome -

It is branched , horizontal growing stem having nodes and internodes on the ondes buds are formed and in lower portion of node give rise to adventitious root.

These buds remain dormant but on favourable condition , it give rise to aerial shoot. eg , ginger , turmeric.


3. Corm -  

 It is spherical , branched and vertically growing , thick stem with more diameter then length.\

It bears reduced internode having few axillary buds which grow into new corn. eg , Arbi (colocasia esculentia) , saffron ( corcus sativis )

4. Bulb - 

In it , the stem is highly reduced and seem as a disc - like structure.

many fleshy , sealy , leaves covers a central terminal bud. Both disc and scaly leaves are called bulb.

These scaly leaves are attached at node of stem

In some plants , outer leaves become dry and form a covering. eg , onion (aiilum cepa) , garlic (allium sativam)

2. Sub-aerial modification

1. Runner - 

It is weak stem which grows horizontally on the surface of soil. so , half stem is in the soil and half is out of the soil. Internodes are completely developed. eg , Grass (cynoden dactylon)

2. Sucker -

These are formed from the node of undergroumd stem.

Stem of sucker both grows horizontally under the soil but sucker comes up in the form of leafy shoot. eg , mint (mentha).


3. Stolon - 

In it , the nodes of underground growing stem give  rise to branches which comes out of the soiland lower part of this node give rise to root. eg , jasmine (jasminum)

4. Offset - 

Stem consist thick and short internodes.

Branches formed from main stem and upper portion of branch curved, which bears group of leaves while lower portion bears root.

Each branch able to grow into new plant after separatinf from parent plant. eg , water hyacynth (eichornia).

3. Aerial Modification

1. Tendrils - 

Stem of plsnt cannot keep upright itself. so , their axillary buds are modified into coiled , wiry , thin structure called tendrils. eg , graphes (vitis vinifera) , groundnut.