Annual Sunflower (Helianthus annuus)

Sunflower (Helianthus annuus) is an annual plant in the Asteraceae (Sunflower) family that is native to the Americas and widespread in California. It possesses a large flower cluster (flowering head). In the Asteraceae family, what is usually called the flower is actually a head (formally composite flower) of numerous florets (small flowers) crowded together. The outer florets are the ray florets (often sterile). In Sunflower these can be yellow, maroon, orange, or other colors. The florets inside the circular head are called disc florets, which mature into seeds. In Sunflower the disc florets are brown. Horticultural varieties are available such as 'Autumn Beauty'. The overall plant can become quite large and the flower heads are large, up to 8 in. in diameter. This plant is most often seen in disturbed areas such as road shoulders, edges of farm fields, and vacant lots. However, it can also be a spectacular performer in the garden if given plenty of room, direct sun, and normal garden watering. Aside for watering, it requires little or no care.

Description from Calscape