Did you know that sunflowers are the only major global crop that is native to the United States? And, that this native plant has about 64 species and subspecies that grow wild here? Wild sunflowers often grow in extreme environments with hot summers, cold winters, and not much water. Plant breeders can use these tough plants to improve and protect commercial sunflowers as new challenges arise.
Those wild sunflower species have been essential to the success of cultivated sunflower. Cultivated sunflowers have been bred for various attributes – more seed oil, more seed, perhaps even prettier colors. But, those cultivars all originated with the wild species.
Wild sunflowers grow in a wide range of habitats. They can be found from central Mexico north across the United States and into southern Canada. Generally each species inhabits a limited geographic range. Wild sunflowers similar to plants the Native Americans first used still grow in many places in North America, especially in the Midwest. These wild plants look very different from cultivated sunflowers, although both are the species Helianthus annuus (see the picture above). Today, farmers plant more than 1.5 million acres of cultivated sunflowers in America each year, and there are 60 million more acres worldwide.
Native North Americans first used sunflower seeds from these wild relatives for food and oil more than 4,000 years ago. They started to select plants with larger seeds in larger flowering heads – for better yields. They also selected plants without branches – making it easier to plant in garden plots.
Despite these initial improvements to domesticate the wild plants, sunflower did not become a primary food crop for the Native Americans. However, the plants clearly made an impression – explorers took seeds back to Europe. When Europeans first brought sunflowers home with them in the mid-1500s the plants were grown mostly as ornamentals. Even though oil could be harvested from sunflower seeds, not many people cooked with it. However, sunflower oil was not an oily food forbidden for consumption by the Russian Orthodox Church during Lent, and the use of sunflower oil increased and became very popular. Russian farmers developed new varieties and the crop spread across Europe.
By the early 1900s, formal breeding was underway. Plant breeders in Ukraine and Russia1 selected for plants that matured earlier, had seeds with increased concentration of better quality oil, and were resistant to diseases and pests that were reducing yield. Sunflower oil remains the primary cooking oil used in many parts of Europe especially in Turkey, Ukraine and Russia.
The Ukrainian and Russian breeders were pioneers in capturing disease resistance and additional useful traits from other wild sunflower species – the sunflower crop wild relatives – to improve the cultivated crop. For example,
- Helianthus tuberosus provided resistance to the diseases downy mildew and rust.
- argophyllus and wild H. annuus both provided resistance to rust.
- tuberosus provided resistance to a parasitic plant, Orobanche cumana, which was destroying sunflower production fields in Europe.
Disease resistance from wild sunflower species has been critical to the continued success of sunflower as a crop. Yet, the most valuable trait for the crop sourced from wild species has allowed breeders to develop sunflower into a hybrid crop. Hybrid crops grow more vigorously and make more seeds than traditional sunflower. This results in greater production from the same number of acres of cultivated land. The plants you see in fields today are almost certainly hybrid sunflowers.
Collecting and preserving the germplasm from wild sunflowers is important. (To read more about seed banks, visit here.) The National Plant Germplasm System is part of the USDA. It retains and distributes the most comprehensive collection of wild sunflowers in the world. Plant breeders use wild sunflower seeds to make cultivated sunflowers more resilient to stress. In the past five years alone, the National Plant Germplasm System sent 30,735 samples to more than four hundred breeders at universities and seed companies around the world who work continuously to improve the sunflower crop.
In today’s world with the loss of arable land, increased production is key to feeding all people. For sunflower, much of the improvement to the cultivated crop has come from the crop’s wild relatives. Breeding programs around the world using the crop wild relatives of sunflowers have allowed this beautiful flower to produce the fifth most important oilseed crop in the world!
Provided by Laura Marek, Iowa State University
Read about more crop wild relatives in these blogs!
And, be sure to visit our main Crop Wild Relative Week page for more information!
- Historical boundaries of these countries have changed throughout time.
About us: This blog is sponsored and written by members of the American Society of Agronomy and Crop Science Society of America. Our members are researchers and trained, certified, professionals in the areas of growing our world’s food supply while protecting our environment. We work at universities, government research facilities, and private businesses across the United States and the world.