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Common Sunflower

Helianthus annuus
Family: 
Asteraceae (daisies, sunflowers)
Description: 

An annual sunflower, extremely variable in height and appearance, with hairy stems. Flowerheads of wild form are many per plant, large, with brown disks, and frequently with a double set of yellow ray florets. Disk usually a couple inches in diameter, not including the rays. Blooms July–November. Cultivated forms often have only one, often huge, flowerhead per plant. Leaves are large, ovate to broad, with irregular, large teeth, mostly alternate except the uppermost ones. Lower leaves are usually heart-shaped. All leaves are rough and hairy.

Similar species: There are 16 species of Helianthus in Missouri. Common sunflower’s leaves have long petioles, lacking wings, and are rather broad, with the larger leaves ovate to heart-shaped with irregular, large teeth, and are mostly alternate except those at the very top. Also, its disks are reddish brown to dark purple, while several other sunflowers have yellow disks.

Size: 
Height: usually to 7 feet in wild forms; cultivated forms can be much larger..
Habitat and conservation: 
Grows scattered in wasteland along roadsides as well as in cultivation. No one knows for sure if this species is truly native to Missouri, since American Indians domesticated and distributed the plant early, and European settlers also spread the plant around. The species was brought to Europe as early as the 1500s. The most famous domesticated common sunflower, the unbranched, large-headed ‘Mammoth Russian’ type, was developed in Russia, then brought to America.
Distribution in Missouri: 
Statewide, scattered. Mostly absent from the Ozarks and Mississippi Lowlands.
Status: 
Scattered and common. The common sunflower is grown worldwide for its seeds and oil, and as an ornamental. It is a tremendously useful plant historically as well as today. It is also beloved by painters, photographers, poets, and novelists. To learn more, read the fascinating (and fun) book “The Sunflower,” by ethnobotanist and enthusiastic sunflower specialist Charles B. Heiser.
Human connections: 
This species is the most important crop plant that is native to the United States. It is cultivated worldwide for sunflower oil, made from the seeds. The plant is also an ornamental and provides food for livestock and wildlife. At one time Missouri was a leading producer of sunflowers.
Ecosystem connections: 
Birds and small mammals eat the seeds, which are rich in oil and proteins, as well as the foliage. Many kinds of insects visit the flowers for nectar and pollen, and other, predatory insects lie in wait for them. Because they grow readily on open or disturbed ground, sunflowers help bind the soil.
Shortened URL
http://mdc.mo.gov/node/3632