There may be more than 350,000 species of flowering plants in the world and 70,000 plants are listed by the RHS.
To stand any chance of being able to recognize individual species and hybrids we need some form of classification.
Flowers are the reproductive structures of flowering plants
Since plants cannot move they must rely on wind, water or animals to carry pollen from the male part of one flower to the female part of another flower in a process known as cross-pollination.
From the earliest times they have been classified into families and this is largely based on the shape and internal structure of their flowers.
So to identify a plant you must first determine which family it is in and in flowering plants that means taking a close look at the flower and its internals.