One of the most important of today’s oil crops, the sunflower is a unique contribution of temperate North America to the world’s major food plants. In addition to its superior oil, the seed of the sunflower is much appreciated as a food. Other parts of the plant were used for a variety of purposes by Native Americans. Today the species is also widely grown as an ornamental for its large showy heads.

Biology

Scientifically, the sunflower crop plant, known as Helianthus annuus var. macrocarpus, is a member of the family Asteraceae. It is an annual, is unbranched, grows from 1 to 3 meters tall, and bears a single large head up to 76 centimeters (cm) in diameter. Each head contains showy yellow sterile ray flowers and up to 8,000 smaller disk flowers. The latter produce the fruits, technically known as achenes, but commonly called seeds. The fruits, from 6 to 16 millimeters (mm) in length, contain a single seed.

In addition to the cultivated variety, the sunflower also includes branched, smaller-headed varieties (Helianthus annuus var. annuus and Helianthus annuus var. lenticularis) that are common as weeds or wild plants in North America from southern Canada to northern Mexico. Forms of the sunflower, particularly those with double flowers or red ray flowers, are cultivated as ornamentals, but more so in Europe than in North America (Heiser 1976).