EXPRESSING ACHENES

Sunflower (Helianthus annuus)

Safflower (Carthamus tinctorius)

ASTERACEAE, Sunflower Family

Most people do not appreciate that plants provide many important oils, i.e., triglycerides. In modern kitchens, corn oil (Zea mays) as a liquid or solid (margarine), is a ubiquitous vegetable oil, but also in the kitchen one can usually find oils from olive (Olea europaea), soybean (Glycine max), sunflower (Helianthus annuus), and safflower (Carthamus tinctorius). In bathrooms one can find shampoos, soaps, and creams containing vegetable oils and their derivatives, e.g., the coconut (Cocos nucifera) and other palm oils. Even medicines sometimes have oil-based components. In the garage one finds paints and special lubricants that have oils from cotton (Gossypium), soybean, castor bean (Ricinus communis), sunflower, safflower, and linseed (flax, Linum usitatissimum).

Estimated world production in 1980 of all commercial vegetable oils derived from seeds and fruits exceeded 65 million metric tons. Moreover, oilseed production has increased steadily in this century and has more than doubled in the last 15 years. Beginning in the 1960s, increases in the demand for vegetable oils were stimulated by shortages and high prices of petroleum (oilseeds are renewable natural resources) and by a strong selection by urbanized countries to use polyunsaturated vegetable oils in place of highly saturated animal fats and butter.

Sunflower oil production has been on a sharp rise since 1960, and is fast becoming a replacement for other oils in the United States. Among the polyunsaturated vegetable oils, sunflower oil and the related safflower oil are better for human consumption than either corn or soybean oil because there are more double bonds present in each triglyceride molecule. Sunflower oil is a semi-drying oil, and is better for paints because it is very low in linolenic acid, but, of course, that is becoming less important economically while the world produces instead mostly latex paints and other polymers. As a salad oil, it is tasteless and equal in quality to olive oil, which is mostly composed of saturated oils; however, researchers have discovered that olive oil has some healthful properties.

Oil is stored in the cotyledons of the sunflower embryo, found within a fruit called an achene. An achene is a one-seeded, dry indehiscent fruit in which the seed coat is not fused tightly to the fruit wall. Therefore, when you shake a sunflower "seed," you are actually shaking the lose seed inside of a fruit wall, the pericarp. The seed has up to 50% oil by weight, and, like soybean, the embryo is fairly nutritious for other dietary needs. Sunflower oil is expressed under pressure and with steam, and after oil is expressed from the embryo the remaining solids are formed into seedcake for livestock feed. This livestock feed is high in protein but good mostly for ruminants because it lacks sufficient quantities of the amino acid lysine. Embryos can be ground into an oily flour, which is tasty when mixed with wheat flour. Experiments have shown that the hulls (pericarps) of sunflower can be pressed into logs for the fireplace and cooking stoves. Whole achenes are important ingredients of bird and rodent feeds, and shelled and unshelled sunflower achenes, salted or unsalted, are a healthy and popular snack.

As its latinized name implies, Helianthus annuus is the "annual sun flower." This species is the only major food crop that originated in the United States. The natives of pre-Columbian U.S. collected sunflower seeds in the wild, and some tribes also cultivated them. Evidence for Salts Cave (1500 B.C.) in Kentucky showed that sunflower was cultivated in the United States before cultivated maize and corn arrived from Mexico. There are some archaeological records of sunflower usage in southernmost Canada and northernmost Mexico. In certain locations, such as in Ohio and North Dakota, there are archaeological remains of sunflower heads as large as those grown today for show. Native Americans ate the oil-rich seeds, discovered medicinal oils for seeds, and paid homage to the plant in religious ceremonies. Oil was obtained by bruising the achenes with a mortar, and heating the pounded mass in boiling water until oil separated and could be skimmed off the water surface. This oil was also used to anoint hair and as a base for body paints. These imaginative Americans also obtained a purple dye from developing achenes.

The sunflower is not actually a flower, but is a large cluster of flowers, a structure called a head or capitulum (an inflorescence). Each head of species in this family (example 1; example 2; example 3; example 4) has hundreds of small, radially symmetrical flowers (disk florets) that are encircled by a ring of showy flowers, which have a broad, yellow corolla (ray florets). The fruits develop from the disk florets. Sunflowers have flowers with an inferior ovary and five stamens, which are fused by the anthers into a ring around the style.

Sunflower is widely recognized as the state flower (inflorescence) or Kansas. However, few people realize that the sunflower may also be the origin of the name of another state--Texas. When sunflower was introduced to Mexico, then including Texas, it was called maiztejas--Texas corn. The word teja means tile, and probably refers to the tile-like arrangement of the achenes on the sunflower head.

Sunflower was introduced to Europe from Mexico and probably also from Canada and the eastern United States. In Europe the showy and large inflorescences were treated as curiosities until the Russians adopted sunflower as a major oilseed crop. All the important early oilseed cultivars were developed in Russia, and much later distributed to other countries. Moreover, the gigantic forms, such as cv. Mammoth Russian, were also developed in the 1880s. About that time, Vincent Van Gogh was painting these beauties, one of which now fetches $30,000,000 in auction. Until recently, the USSR produced 90% of all sunflower oil, where up to 12 million acres of sunflowers were grown, particularly in and around the Ukraine. Plants were bred to have uniform characteristics, so that they could be harvested with common harvesting machinery. Sunflower plants that are cultivated for oil or edible seeds are typically less than 1.5 meters tall and have relatively small heads.

Stems of sunflowers were used by native Americans in construction of hoods over baking stoves and have been used as emergency fuel and for compost. There has been some interest in using stems for commercial fiber, e.g., paper production, and the Soviets made acoustical ceiling tile and life preserves from stem fibers, while the Chinese tested stems for making fabric.

Related to sunflower is the Jerusalem artichoke, Helianthus tuberosus, which is not, of course, native to Jerusalem and is not a true artichoke. This species is a perennial of the northeastern United States and apparently was not cultivated per se by native Americans, who instead dug up the below-ground tubers of wild plants. Under cultivation, this species has been selected for larger tubers. A major development occurred in the 1950s when a sterile hybrid was formed between the annual sunflower and H. tuberosus to form the 'Sunchoke'. There has been casual interest in Sunchoke as a perennial sugar crop.

Safflower

Many of the characteristics noted for sunflower also apply to safflower, which is another species of the Asteraceae (sunflower family). Like sunflower oil, safflower oil is polyunsaturated and therefore is useful in lessening the threat of human arteriosclerosis. It is also an annual crop, usually less than one meter tall, and it can be mechanically harvested. Forms up to two meters in height are common in the Turko-Afghanistan region.

Safflower is native to the Old World, and the genus occurs naturally in the Mediterranean region, northeastern Africa, and southwestern Asia to India. There are positively identified archaeological records of safflower from 4000-year-old Egyptian tombs, including a find of single safflower flowers wrapped in willow leaves that were placed with a mummy from the 18th Dynasty (ca. 1600 B.C.). The flowers of Carthamus are pale yellow to red-orange, tubular disk florets; there are no ray florets in this thistle-like head. Since ancient times, orange pigments have been obtained from safflower. In fact, the name safflower may be derived from another plant, saffron (Crocus sativus), which was a precious and very expensive yellowish dye obtained from the stigmas of freshly opened flowers. The name Carthamus is the latinized form of the Arabic word quartum or gurtum, which refers to the pigment color. The corolla as a water-soluble yellow dye (carthamidin, an anthocyanin) and a water-insoluble orange-red dye (carthamin), which is readily soluble in an alkaline solution. Dyes were produced from fresh flowers, which were collected during morning shade and dried on muslin trays before storing in tins. Other methods of producing safflower dyes included collecting the heads of flowers before they faded on the plant and removing the yellow corollas. The yellow dye could be extracted by washing the corollas for three to four days in acidified water, which made the pigment dissolve.

Safflower oil is a drying oil that is used in white and light-colored oil-based paints instead of linseed oil, because it does not yellow with age like similar oils rich in linoleic or oleic acid (depending on cultivar). Safflower was used as a substitute for more precious oils. Likewise, safflower pigment was used as a substitute for or an adulterant of saffron, e.g., as a coloring agent in cheeses. Safflower was particularly important as an oil and pigment in southern Asia (Iran, Afghanistan, and India), and early carpets from these regions used safflower dye. Safflower arrived in China relatively late (200-300 A.D. according to current records), and the dyes became important there. In China safflower oil was considered inferior to sesame oil but nonetheless is mixed with sesame and cottonseed oil in the preparation of Japanese tempura. The Japanese cosmetic beni is also made from safflower, and French chalk was mixed with safflower to make a cosmetic. In India and Afghanistan, saffron rice is made with safflower, which gives it an interesting orange color. Moreover, over the centuries safflower has been used commonly in potions and folk medicines throughout the Old World.

Safflower cultivation is now widespread, and one can see many fields of these plants in dry areas of the southwestern United States, such as in California and Arizona, because this species is fairly drought resistant and salt tolerant. Each plant forms one to two dozen heads of flowers, which are quickly converted into full heads of fruits (again, achenes), because the flowers are self-compatible and self-pollinated. Presence of honey bees can increase production. Oil content of the achenes is frequently 30-45%, and protein content can be as high as 24%. After the oil is expressed, safflower seedcake can often be used for livestock feed, and the remaining plant, if not too spiny, can be used for green fodder or silage.

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