Stem :

It can be defined as the ascending part of shoot axis which is negative geotropic, positively phototropic and develops from plumule of embryo.

 

 

Shoot System :

1. It constitutes the aerial plant lying above the soil.
2. The main axis with its branches, leaves, flowers and fruits is collectively called shoot system. The axis of shoot is called as stem.
3. The branches bear flat, green, expanded lateral out-growths called as leaves.
4. They are borne on special points known as nodes. The distance between two adjacent nodes is known as internode.
5. The upper angle formed between the leaf and the stem is called axil. A lateral bub which develops in the axil of leaf is known as axillary bub.
6. At the tip stem branches lie the terminal or apical bub.
7. It is responsible for increasing the length of the stem.

Functions of stem

The chief function of stem are :

1. To hold the leaves, flowers and fruits.
2. To expose the leaves to sunlight.
3. To expose the fruits and seeds for proper dispersal.
4. To conduct the water and minerals from roots to leaves.
5. To transport the food from leaves to all parts of plant such as roots, flowers. fruits etc.

 

Stem usually grow above the soil and termed as aerial stem. Sometimes the stem may remain underground to be called as underground or subterranean stem.