Annual Sunflower (Helianthus annuus)
Synonyms: Common Sunflower
A robust annual that produces cheery yellow flowers, 2-4 inches across with purplish-brown centers. Has allelopathic properties. Distributed throughout U.S., southern Canada and northern Mexico; abundant in roadsides, waste places and other open sites. Best in full sun, dry
soils; highly adaptable, produces seeds that attracts seed-eaters.