Sunflower

Sunflowers are usually tall annual or perennial plants that in some species can grow to a height of 300 cm (120 in) or more. They bear one or more wide, terminal capitula (flower heads), with bright yellow ray florets at the outside and yellow or maroon (also known as a brown-red) disc florets inside. Several ornamental cultivars of H. annuus have red-colored ray florets; all of them stem from a single original mutant. During growth, sunflowers tilt during the day to face the sun, but stop once they begin blooming. This tracking of the sun in young sunflower heads is called heliotropism. By the time they are mature, sunflowers generally face east. The rough and hairy stem is branched in the upper part in wild plants, but is usually unbranched in domesticated cultivars. The petiolate leaves are dentate and often sticky. The lower leaves are opposite, ovate, or often heart-shaped.
Read less