characters like leaf venation, vascular bundles, Bentham and Hooker, two British botanists, gave a system of classifying angiosperms which is published in ‘Genera Plantarum’. It was the first natural system of plants classification which gave detailed description of 97205 species of seed plants along with their geographical distribution. Therefore the system was immediately adopted after its publication. The system has been based on morphological characters of vascular strands, floral organs, number of cotyledons in seed and presence and absence of cover around seeds.