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.
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)
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.
1. Storage eg.Potato
2. Perennation e.g. Ginger
3. Vegetative Propagation e.g Potato
4. Photosynthesis e.g Opuntia