Organography means the description of various organs of plants and animals. The external features of plant organs like stem, root, leaf, fruits, etc. Stem and root form two re­gions of the plant axis whereas leaf is a lateral continuation of stem and has a limited growth.

Func­tionally these parts are quite different. While roots help in anchorage, absorption of water and miner­als and storage, stems help in conduction of food materials and water besides providing mechanical strength to the plant. Leaves help in photosynthe­sis, exchange of gases and transpiration.

The func­tional differences are mainly due to differences in their internal organization. The internal structures of these parts exhibit variations in cell structure and tissue arrangements. The tissues are arranged in these organs to provide maximum functional ef­ficiency and mechanical strength.