Theory:

The plant part which is seen above the ground is the shoot system.
 
The shoot system has the following major parts:
1. stem
2. leaves
3. flower
4. fruits
 
Let us see stem and leaf in detail.
 
Stem:
Stem is the strongest part of the plant, grows negatively to geotropic, means grows upward against gravitational pull.
Stem grow towards light. Wherever it finds light it grows towards it either vertically or by curving its branches.
Plant_nodes_c.jpg
  • Stem has nodes from which leaf grows.
  • Internodes are nothing but the stem that is between two nodes.
  • There will be a bud at the tip of the stem called as terminalbud. Buds found at the base of the leaves or at the axils of the leaves are termed as auxiliary buds.
The following are the major functions of the stem:
  • Stem supports all the other parts found in the plant like branches, leaves, flowers and fruits.
  • It through the stem the nutrients and water are distributed to other parts of the plants.
  • In some plants (like sugarcane) stem is used to store the excess food of the plants.
Leaf
The leaf is the most important part that not only make the plants beautiful but also enable the plant to make its own food.
The leaf out grow from a stalk called petiole attached to the stem. Some leaves are broad some are narrow. The flat surface of the leaf is called lamina or leaf blade. The petiole extend as midrib in the leaf with veins branching out from them. Some leaves have a small outgrowth called stipules on either side of the auxillary bud.
 
Leaf_1_web.jpg
 
Most of the leaves are green in colour because of the pigment called chlorophyll. In the lower side of the lamina are stomata or small pores through which gaseous exchange and transpiration happens.
 
The major functions of the leaves include:
  • Respiration (breathing)
  • Photosynthesis (making its own food)
  • Transpiration (movement of water vapour through stomata)