Three seeds are used in fiber production:
Of these three, cotton has been and continues to be a very important seed fiber used by humans. Cotton is a soft, fluffy seed fiber that comes from the boll (a seed pod). Each boll has about 7-8 seeds in which the fibers grow. When the boll is ready, it opens and the fibers spread out. Cotton bushes are 3-6 feet/1-2 meters high.
Cotton has been grown for thousands of year; it was used by people in Mexico, Peru, India, Egypt and China long before it ever hit the shores of the New World. The European colonists planted cotton soon after their arrival – at least the colonists in the southern part of what is now the U.S.
Cotton requires a long growing season and temperate climate with good rainfall or irrigation. Why? Because cellulose won’t form in temperatures below 70F/21C, and cotton is almost pure cellulose! Not surprisingly, cotton grew well in the rolling lands of the southern colonies, later states. (The wealth of the antebellum South, in fact, rested on three labor intensive crops: cotton, rice and indigo.)
In the U.S., cotton production was spurred on by Eli Whitney’s invention (patented in 1794) of the cotton gin, a mechanized process separating the cotton fiber from the boll. The cotton gin also cemented slavery in the southern U.S., long after it ended in the northern U.S.
For a long time, cotton could only be picked (painfully and laboriously) by hand; John Rust’s mechanized cotton picker wouldn’t be patented until 1933. In the southern U.S. that back-breaking work was done, for the most part, by African-American slaves. Yet the Civil War didn’t stop abusive labor practices; poor African Americans and white Americans continued to pick cotton – to the modern day, in fact. (I remember in the mid-1990s, an African-American student explained to me that his football scholarship was only a means to an end; he was determined to do well academically so he could succeed in business and take care of his mother. His mother was a single woman who picked cotton in order to put food on the table.)
Okay, I’ve drifted off topic a bit.
Whether picked by hand or machine, the cotton goes to a cotton gin where the seeds are separated from the fibers.
- The fibers – lint – are pressed into bales and ready to be sold to a spinning mill.
- The seeds will be covered with very short fibers called linters. These are then removed and can be used in producing rayon and acetate.
- The seeds are crushed to obtain cottonseed oil.
Cotton fibers range from 1 to 2 micrometers (one thousandth of a millimeter or one 25-thousandth of an inch) in diameter. Natural cotton is a creamy white though dulls with age and can be grey-ish if rained on right before it is harvest. If you have cotton fiber with brown flecks, that cotton has been poorly ginned. Those brown flecks are bits of organic matter (e.g., plant parts or even dirt) and, of course, decrease the quality (and thus price) of the cotton.
There are some natural-colored cotton. According to Wikipedia,
Naturally pigmented green cotton derives its color from caffeic acid, a derivative of innamic acid, found in the suberin (wax) layer which is deposited in alternating layers with cellulose around the outside of the cotton fiber. While green colored cotton comes from wax layers, brown and tan cottons derive their color from tannin vacuoles in the lumen of the fiber cells.
Long staple cotton fibers, sometimes identified as Pima, Superpima, long-staple or extra-long-staple, can be made into smoother and stronger fabric and are generally costlier than regular, ol’ cotton fiber.
Estimates for world production are about 25 million tonnes or 110 million bales annually. While the U.S. is still the largest exporter of cotton, China is now the major producer (though most of it is used domestically). The top 10 producers of cotton (in order from largest to smallest) are: China, India, the U.S., Pakistan, Brazil, Uzbekistan, Australia, Turkey, Turkmenistan and Greece. According to Wikipedia, 2.5% of the earth’s arable land is used for cotton production.
Interesting side note (from Wikipedia): Cotton has been genetically modified for resistance to glyphosate a broad-spectrum herbicide discovered by Monsanto which also sells some of the Bt cotton seeds to farmers. There are also a number of other cotton seed companies selling GM cotton around the world. … Cotton has gossypol, a toxin that makes it inedible. However, scientists have silenced the gene that produces the toxin, making it a potential food crop.