Why are there so many types of flowers?

to make the world a better place and full of color 

Hi Betty,
Just as we have so many different types of: animals, trees, stones, people, opinions, books, cars, dishes.......flowers.......  a veriaty that enables you to find / choose the one (or more) that you love / prefer. 
Best regards,

Apparently God likes variety. 

I agree that God likes variety but people do too. Flowers such as roses, day lilies, mums, prim roses are examples of flowers that people "play" with always creating new varieties.

There are so many types of flowers, because of evolution in both nature and science. For instance some flowers such as Red Roses have been around for thousands of years, but their bloom or color changes due to natural factors like wind and bees which carry pollen from one plant to another "creating" new species, it's just like with humans being so different due to different genes. On the other hand, scientists always want to attain the impossible. For instance, Blue Tulips or Blue Carnations do not grow naturally, so by hybridization, botanists have taken blue pigment and altered their DNA to obtain these blue flowers .

For more details on flower species go to Online Flowers Guide.