Sunflower (Helianthus annuus)

Picture Notes: These sunflower pictures (Fig. 01 & 03) were taken on 08/07/2012 while riding through a farming valley near Yerington, NV on a return trip from Lake Tahoe.

Description: Sunflower (Helianthus annuus) is an annual plant native to the Americas. It possesses a large inflorescence (flowering head), and its name is derived from the flower's shape and image, which is often used to depict the sun. The plant has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads of flowers. The heads consist of many individual flowers which mature into seeds, often in the hundreds, on a receptacle base. From the Americas, sunflower seeds were brought to Europe in the 16th century, where, along with sunflower oil, they became a widespread cooking ingredient. Leaves of the sunflower can be used as cattle feed, while the stems contain a fiber which may be used in paper production. What is usually called the "flower" on a mature sunflower is actually a "flower head" with many florets, smaller flowers, crowded together. These flower heads can be up to 5 inches across. The outer petal-bearing florets (ray florets) are sterile and can be yellow, red, orange, or other colors. The maroon or brown florets inside the circular head are called disc florets, which eventually mature into seeds. The flower petals within the sunflower's cluster are always in a spiral pattern. Generally, each floret is oriented toward the next producing a pattern of interconnecting spirals (Fig. 02), where the number of left spirals and the number of right spirals are successive. 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. The heads follow the sun each day, facing eastward in the morning, westward at sunset; the name in Spanish means turns toward the sun. Sunflowers commonly grow to heights between 5–12 feet. The tallest sunflower confirmed by Guinness World Records, 26 feet, 3 inches, was in Germany in 2009. The plant has been cultivated in Central North America since pre-Columbian times; yellow dye obtained from the flowers, and a black or dull blue dye from the seeds, were once important in Native American basketry and weaving. Native Americans also ground the seeds for flour and used its oil for cooking and dressing hair. In the 19th century it was believed that plants growing near a home would protect from malaria.