The wild zinnia, a nondescript small flower, was first found growing in Mexico in 1519 and introduced to European and American gardens. Originally known in Europe as the "Poorhouse Flower" a later common name was the "Cinderella Flower" because of the transformation of the original flower into the varied colors and forms that later evolved. It was named after Dr. Zinn, an 18th century German whose hobby was hybridizing wild flowers.
In 1886 a French botanist produced the first double, and in 1920 Luther Burbank, an American, produced the first dahlia type zinnia. Today, the diversity of colors and flower forms is a living testimony to the science and art of the plant hybridists.
A member of the compositae or sunflower family, to which most daisy-like flowers belong, it blooms now in every color except blue. The plants thrive in heat, and should have good air circulation. Confine your watering to the roots only, so that the leaves don't get wet, because zinnia plants are susceptible to mildew.
If you examine the flowers carefully you may see that there are two types of flowers: the inner or "disc" flowers and the outer petal-like "ray" flowers. In the double forms, the "disc" flowers have taken on the characteristics of the ray flowers. The zinnia is an annual, but it has come a long way to spend each summer in our gardens.