sunflower, any plant of the genus Helianthus of the family Asteraceae (aster family), annual or perennial herbs native to the New World and common throughout the United States. In cultivation, the flower heads, commonly having yellow rays, sometimes reach 1 ft (30 cm) in diameter. The common sunflower (H. annuus) is an annual, native from Minnesota to Texas and California and perhaps also in Central and South America. Native Americans cultivated the plant and found many uses for it: the nutritious seeds were eaten raw, made into a meal, or used as a source of hair oil; a yellow dye was obtained from the flower heads, and a fiber from the stalks; the roots of certain other species were eaten. Today the common sunflower is widely cultivated; it is particularly valued in the countries of the former Soviet Union, where the seeds are made into bread. The seeds are almost universally used as a poultry food and principally as the source of an oil utilized for such purposes as cooking and soapmaking; the oil cake is fed to stock. The common sunflower is the state flower of Kansas, and a sunflower is regarded as the floral emblem of Peru, where it was revered by the ancient sun worshipers. Several other species are in cultivation—some are garden flowers; the Jerusalem artichoke is a food plant. Other plants are sometimes called sunflower. Sunflowers are classified in the division Magnoliophyta, class Magnoliopsida, order Asterales, family Asteraceae.

Any of 60 species of annual herbaceous plants in the genus Helianthus (composite family), native mostly to North and South America. The common sunflower (H. annuus) has a rough, hairy stem 3–15 ft (1–4.5 m) high; broad, coarsely toothed, rough leaves 3–12 in. (7.5–30 cm) long; and large (3–6 in., or 7.5–15 cm, in diameter), flat, platelike compound flowers. Disk flowers swirl in a tight brown, yellow, or purple spiral; ray flowers are yellow. The leaves are used as fodder, the flowers yield a yellow dye, and the seeds contain oil and are used for food. The oil is used for cooking, as an ingredient of soaps and paints, and as a lubricant. Only a few species are cultivated, some for their spectacular size.

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