Helianthus annuus, commonly known as the sunflower, is a tall, bright yellow flowering plant native to the Americas. It belongs to the Asteraceae family and is known for its large, round flower heads that can reach up to 12 inches in diameter. The plant typically grows between 3 to 10 feet tall and has broad, rough leaves. Sunflowers are known for their unique ability to turn their flower heads to follow the sun, a behavior called heliotropism. They are cultivated for their seeds, which are rich in oil and nutrients, and are also used for ornamental purposes in gardens.