In September the fields and roadsides of the Great Plains erupt in a blaze of yellow as the sunflowers and goldenrods (also members of the sunflower family) make their presence known to the local pollinating insects. While many sunflower species may begin blooming in July, they are not as noticeable then as later on when they have grown up and over the surrounding vegetation. There are eleven species of sunflower recorded from Kansas. Most of them are perennials. Only the common sunflower and H. petiolaris, the Prairie Sunflower, are annuals. Identification of sunflowers can be very complicated because they frequently hybridize and even within species there is a high degree of variability. With a little practice, however, the most common species can be readily recognized.
The Common Sunflower has a long history of association with people. Nearly 3,000 years ago it was domesticated for food production by the Native Americans. The seeds of the wild type of sunflower are only about 5 mm. long. It was only through careful selection for the largest size seeds over hundreds of years that the cultivated sunflower was produced. Lewis and Clark made mention in their journals of its usage by the plains Indians. It was brought back to the Old World by the early European explorers and widely cultivated there also. Today it is a common alternative crop in the Great Plains and elsewhere for food and oil production.
The wild cousins of those grown on the farm are still common, however, in fields, roadsides and disturbed ground throughout the Great Plains.
The Common Sunflower is a typical member of the Asteraceae, one of the largest and most successful families of plants. Within the structure we think of as the "flower", it actually has two different types of flowers - ray and disk flowers.
The ray flowers have the big, straplike structures that we see around the edge of the "flower" while the disk flowers occupy the middle of it. Within the Asteraceae, many confusing combinations of the two are possible along with the total absence of one or the other in some species! Individual ray or disk flowers may be male, female or both and either fertile or infertile (do or don't produce seeds). In sunflowers, the ray flowers are usually female and infertile. The disk flowers are both male and female and are fertile.