Sunflower seeds are produced by the sunflower plant, an erect annual that can grow up to 10 feet high. The heads of the plant can become as large as 12cm in diameter. In the centre of each head are the sunflower seeds, which are actually achene, meaning they are the fruit of the plant. The seeds are located under a thin hull which must be removed before eating. Sunflower seeds are commonly grown all around the world for their numerous uses.
The sunflower was first domesticated for its seeds somewhere around 1000 B.C. in North America. The plant was then transported to Europe by 16th century Spanish explorers. However, sunflower seeds weren't considered a food crop until the 1860s, when Russia began to develop the proper technology to cultivate and harvest them. By the 1940s, Russian farmers had grown sunflower seeds that contained nearly 50 per cent oil content, while the American grown varieties yielded around 20 to 30 per cent. The sunflower seed has since been developed into a snack food, as well as a primary source of sunflower oil, which has many modern uses.
Sunflower seeds are formed in the head of the sunflower. Each head consists of between 1,000 and 2,000 individual flowers. Each of these flowers eventually produces a seed, which can be harvested about 30 days after pollination. The yellow petals that form around each of the sunflower heads are also individual flowers, called ray flowers. The seeds of the sunflower are about a half inch in length, and can be completely black or have thin white stripes.
Solid seeds are known as black oil sunflower seeds, and are primarily pressed into oil. Striped seeds, known as stripers, have a lower oil content, and are used for culinary purposes. An additional type of sunflower seed is completely white, and has no real commercial or economic use.
Sunflower plants are native to and were first domesticated in North America. However, they can grow in any temperate region in the world. Sunflower seed crops are grown in North and South America, Europe, Asia and Africa. Russia is the largest producer of sunflower seeds, as their crops take up 17,098,242 square kilometres.
The primary use of sunflower seeds is for the oil produced. It is considered to be a premium oil because of its light colour, low fat content and mild flavour. In most sunflower seed producing countries, it is the preferred cooking oil. However, it is almost never used in the United States, where sunflower seeds are more commonly eaten as a snack food. They are also mixed into birdseed and ground into meal to feed livestock.
Sunflower seed crops are best grown in temperatures between 17.8 and 32.8 degrees Celsius. Extremely hot temperatures can cause a decreased level of oil and seed production from the plants. Sunflowers require a large amount of sunlight, and the head of the plant will often follow the sun as it rises and sets. Sunflower seeds must be grown in soil that is low in salt content, as large quantities can reduce the oil production. Moderate soil drainage is required to prevent diseases, and sandy or clay soils are recommended.
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- University of Missouri Extension -- Department of Agriculture -- Sunflower: An American Native
- University of Purdue - Departments of Agronomy and Plant Genetics, Entomology and Plant Pathology -- Sunflower
- University of Minnesota Extension -- Department of Horticulture -- Yard and Garden Brief: Sunflowers