Characteristic features and Functions of the stem

Shoot System

The plumule of the embryo grows into the stem which forms the main axis of the plant. The stem along with the leafy branches constitutes the shoot system of the plant.

Characteristic features of the stem

   The stem is the ascending portion of the main axis of the plant.

   It is positively phototropic and negatively geotropic.

   It has well developed nodes and internodes.

   It has a terminal bud at the apex.

The stem bears flowers and fruits.

   Lateral branches of the stem are exogenous in origin i.e they arise from the tissues which are in the periphery of the main axis (cortex)

Buds: Buds are the young shoot, yet to develop. They have compressed axis in which the internodes are not elongated and the young leaves are closed and crowded. When these buds develop the internodes elongate and the leaves spread out.

When a bud is found at the apex of the main stem or branch it is called terminal bud or apical bud. When a bud arises in the axil of a leaf, it is known as axillary bud. Certain buds develop in positions other than the normal. Such buds are known as adventitious buds. e.g. Bryophyllum. In this buds arise on the leaves. These are called epiphyllous buds.

Functions of Stem: The primary functions of stem is 1. to support the branches and leaves. 2. It conducts water and minerals from the roots to the leaves and the food materials from the leaves to the roots. The secondary functions of the stem are 

1. Storage eg.Potato 

2. Perennation e.g. Ginger 

3. Vegetative Propagation e.g Potato

 4. Photosynthesis e.g Opuntia