The ‘flower’ of the sunflower, sometimes as large as 80 centimeters in diameter, is actually a flower head composed of i.a. numerous small flowers called ‘disk flowers’ or ‘florets’.
On the outside of the flower head is a series of greenish bracts [little leaves]. Next to the bracts are the ray flowers [they resemble petals], which are usually yellow. They are sterile; their function is to attract insects. The tubular disk flowers in the center of the head are smaller and quite different in shape and color.
The disk flowers are arranged spirally. Normally, they are cross-pollinated by bees. Commercial sunflowers [hybrids] have flowers that are self-compatible for pollination, meaning they do not require a pollinating insect.
A single flower head produces 350 to 2000 seeds. Seeds are generally less than 1.5 cm long, pointed at the base and round at end. The color of seeds may be white, black or black white with stripes.