Taxonomy is the branch of biological science which includes nomenclature and classification of the organisms into groups based on their shared features and characteristics. Classification is the process of grouping organisms based on observable features into categories called 'taxa'. The ranks/taxa have the following sequence from largest to the smallest with similarities in organisms increasing at each step. Kingdom, phylum/division, class, order, family, genus and species form the hierarchy in classification where kingdom is the largest rank and species is the lowest with maximum similarities.
All the plant type names given belong to same group at 6th position which is division Angiospermae.
Of the four plants, wheat is a monocot and rest are dicot. Position 5 is class Monocotyledonae and position 4 is class Dicotyledonae. After class is the order rank and wheat comes in the order Poales.
Mango (Mangifera indica) belongs to the order Sapindales and the genus Datura and Petunia come under the order Polymoniales.
