Clark's Oregon Wildflower Blog: Sunflowers!

Almost everyone knows something about sunflowers; or sunflower seeds, oil, bird feed, and even famous paintings! Wild common sunflowers (Helianthus annuus) grew naturally in our own Southwest more than 5000 years ago and our native residents were quick to cultivate them for food and other non-food uses. Sunflower seeds were brought back to Europe in the 16th century, where they were also cultivated extensively. The Incas and the Aztecs thought of the sunflower as a symbol of the solar deity in their culture.

In the mid 1700's Russians began to cultivate sunflowers for oil production. This was largely due to the prohibition of using other oils during Lent. Using sunflower oil was apparently OK. By the early 1800's, large scale production had started in Russia. Then, in the late 1800's those Russian seeds made their way back to North America, where immigrants likely planted their hybridized sunflowers.

It seems like when I was in grade school, we all grew sunflowers in class as a science project. They are easy to grow and hard to kill, so that makes for a good kid's project! And they do grow quickly. No doubt this is one reason the natives took a liking to them. Some writings say sunflowers were cultivated before corn.

There is a common myth that sunflower heads track the movement of the sun during the day. In fact, most sunflowers face east throughout the day. Another interesting sunflower fact is the giant flower head on some varieties is not a single flower, but a composite of many smaller ones. This allows the plant to produce hundreds of seeds on each composite.

And here's some content for all you math fans out there, courtesy of Wikipedia. The flower petals within the sunflower's cluster are always in a spiral pattern. Generally, each floret is oriented toward the next by approximately the golden angle, 137.5°, producing a pattern of interconnecting spirals, where the number of left spirals and the number of right spirals are successive Fibonacci numbers. Typically, there are 34 spirals in one direction and 55 in the other; on a very large sunflower there could be 89 in one direction and 144 in the other. This pattern produces the most efficient packing of seeds within the flower head.

Sunflowers commonly grow to heights between 1.5 and 3.5 m (5–12 ft.). The tallest sunflower confirmed by Guinness World Records is 8.0 m (2009, Germany). In 16th-century Europe the record was already 7.3 m (24 ft., Spain).

Sunflowers have been highly hybridized, so it is rare to find truly wild plants growing naturally. We did see some on our recent trip to Colorado, but in reality it is hard to tell if they are wild or hybrids.