In Greek "helios" means sun and "anthos" means flower, thus Sunflower. The name is just apt for a plant that turns its flower to face directly into the sun as it passes and also looks like the sun in its yellow rays. Helianthus annuus is a highly variable species that is indigenous to North America. There are so many different-looking cultivars of sunflower that it's hard to make generalizations about the whole species. Most sunflowers are tall 8-15 ft (2.4-4.6 m); most have rough-hairy oval to heart shaped leaves; most have large flowerheads 8-12 in (20-30.5 cm) across; and most have yellow ray florets and purplish brown disk florets. The ray florets of sunflowers are sterile, and only the disk florets produce seeds.