Helianthus anuus

Helianthus anuus

Plant | Helianthus anuus | Sunflower (Helianthus annuus) is an annual plant native to the Americas that possesses a large inflorescence (flowering head). The sunflower got its name from its huge, fiery blooms, whose shape and image is often used to depict the sun.

The sunflower has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads of flowers. The heads consist of 1,000-2,000 individual flowers joined together by a receptacle base. 

Helianthus anuus

Scientific classification
Kingdom      :     Plantae
(unranked)   :     Eudicots
(unranked)   :     Asterids
Order          :     Asterales
Family         :     Asteraceae
Subfamily    :     Helianthoideae
Tribe           :     Heliantheae
Genus         :     Helianthus
    Binomial name
Helianthus annuus

Helianthus anuus

The Annual Sunflower is thought to be adventive from western United States. However, it was cultivated as a source of food by native Americans, and was likely introduced to Illinois by them prior to European settlement. The cultivated sunflower of modern agriculture is a self-pollinating hybrid of this plant and another annual sunflower that occurs in the Great Plains. Because of its large heart-shaped leaves, it is easy to distinguish the Annual Sunflower from other Helianthus spp. that occur in the Midwest.

Helianthus anuus

History
The sunflower is native to Central America. The evidence thus far is that it was first domesticated in Mesoamerica, present day Mexico, by at least 2600 BC. It may have been domesticated a second time in the middle Mississippi Valley, or been introduced there from Mexico at an early date, as maize was. The earliest known examples of a fully domesticated sunflower north of Mexico have been found in Tennessee, and date to around 2300 BC.