Sunflower is the common name of one of the plants in the Helianthus genus in the flowering Asteraceae family (known as the asters, daisies, or sunflower family).
It is also often used explicitly about the annual Helianthus annuus, the common sunflower characterized by large flower heads (inflorescences) and a long stem. The Helianthus genus comprises more than 50 sunflower species, all native to North America.
Helianthus annuus has an erect, thick, and hairy stem that forms a large inflorescence. The plant has large, broad lower leaves that are oval and alternately arranged on the stem, and narrower, smaller upper leaves that are individually attached to the stem.
The inflorescence is a large disc with a 10 to 30 cm diameter and consists of 16 to 30 golden yellow florets. Sunflowers are annual plants harvested after a growing season and can reach heights of 1 to 3.5 m (3.3 to 11.5 ft).