Dear student,
Artificial system of classification was given by Linnaeus which was based on vegetative structures, external and morphological characters. He gave equal weightage to vegetative and sexual characters. Vegetative characters are easily modified by the environmental factors. This was the reason for rejection of artificial system of classification.
Natural system of classification was given by Bentham and Hooker and was based on morphological and anatomical features. It does not take into account evolutionary history of the organism and considers species to be static and no role of f fossils was shown in this system of classification. Therefore this system of classification was rejected.
Regards