Sunflower
Family Compositae (or Asteraceae)
Helianthus annuus, the sunflower (H. annuus 1), is a stout erect annual herb, up to 3 m tall, coarsely haired on its stem and leaves which are spirally arranged, simple, ovate, and with long petioles. The large terminal flower heads (H. annuus 2), up to 30-40 cm across, are composed of bright yellow asexual ray florets and brownish, tubular, bisexual disc florets. The ‘ seeds’ (H. annuus 3) are botanically achenes, up to 18 mm long and variable in colour: white, brown, black or dark with white stripes. They contain 25-30% oil.
Distribution
The cultivated sunflower is not known in a wild state, but probably derived from the branched form (H. annuus 4) which is a native of northern America. The plant was introduced into Europe in 1510 when seeds were planted in the botanical garden of Madrid. Peter the Great took it to Russia in the 18th century. Today sunflowers are distributed worldwide in many varieties, including giant types, semi-dwarf types and dwarf types. Sunflower seeds were an important source of food for the North American Indians.
Use
Today sunflowers are mainly grown as an oil crop. The oil content is increased to 50% by cultivation, and consist for 90% in oleic acid and linoleic acid. The edible oil is extracted from the seed kernels and is used in cooking and the manufacture of margarine and compound cooking fats. Mixed with other oils it is used in paints and varnishes, and as a lubricant. The press cake, which is rich in proteins, is used as food for livestock.