In artificial system of classification, only a few characters of the plants are being considered, for example, the grouping of plants into shrubs and trees or the sexual system of Linnaeus based on number of stamens and styles. The best known artificial system is of Linnaeus published in 1735. In natural system of classification, all the important characters of the plant are being considered, and the plants are classified according to their related affinities. Bentham and Hooker gave the natural system of classification. Phylogeny system in phylogenetic system of classification the plants are classified according to their evolutionary and genetic affinities. This system of classification was proposed by Engler in $1886$, Hutchinson in $1926$.