Cotton Plants and Types of Cotton Species

Cotton is produced by small trees and shrubs belonging to the mallow family, which also includes hibiscus, okra, and the swamp mallow. The immature flower bud, called a square, blossoms and develops into an oval boll that splits open at maturity, revealing a mass of long white seed hairs, called lint, that cover a large number of brown or black seeds. When fully mature and dry, each of these hairs is a thin flattened tubular cell with a pronounced spiral twist and is attached to a seed. The length of the individual fibers ranges from 1.3 to 6 cm (0.5 to 2.5 in). Shorter fibers that grow from the seeds are called linters.

A few species are grown commercially; these range from a small tree of Asia, to the common American Upland cotton, a low, multibranched shrub that is grown as an annual.

Another species includes the long-fiber Egyptian and Sea Island cottons botanically derived from the Egyptian species brought to the United States about 1900.

Sea Island Cotton

Sea island Cotton thrives in the unique climate of the Sea Islands, located off the southeastern coast of the United States, and on the islands of the West Indies such as Barbados.

Egyptian Cotton

As with Egyptian cotton, the fiber is white and lustrous but its fiber length is longer than that of any other type of cotton, which permits the spinning of extremely fine yarns.

Pima or American-Egyptian Cotton

Pima, originally called American-Egyptian cotton, is a hybrid type. It is the only variety of long-fiber cotton now grown in commercially significant quantities in the United States, where it is cultivated under irrigation in the Southwest. Genetically modified cotton seeds have also been introduced, resulting in greater yields.

Upland Cotton

In the U.S. there are fourteen major cotton growing states that produce Upland cotton. They are Alabama, Arizona, Arkansas, California, Georgia, Louisiana, Mississippi, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee, Texas and Virginia. Some cotton is also grown in Florida, Kansas and New Mexico. American Pima cotton is grown in Arizona, California, New Mexico and Texas. All of these states form a region in the United States known as the Cotton Belt and have three things in common, lots of sunshine, water and fertile soil, very important to growing a good cotton crop.

Upland cotton being the most common type in the U.S. has a staple length (length of fiber) of 13/16 to 1 ¼ inches. The American Pima has a staple length of 1 5/16 to 1 ½ inches. These plant types grow and mature at different rates and lengths of time, but basically mature within a 30 day period of each other.

Cotton plants have a general time frame in which they grow and produce after planting (introducing the seed to moist soil). With ideal conditions, the planted cotton seed will germinate (to begin to grow) or sprout and emerge in about five to ten days. The first 2 leaves that are visible on the young cotton plant are seedling leaves called cotyledons (cot-a-lee-dons). They are useful for absorbing sunlight into the plant. The sunlight is then converted through a process known as photosynthesis, into nourishing carbohydrates that will help the plant grow.

In about two to four weeks they turn over the photosynthetic task to true leaves (leaves produced subsequent to the cotyledons) which continue the feeding process for the duration of the plants life. The plant continues to grow, adding leaves and height, and in approximately five to seven weeks, small flower buds called squares (a small flower bud covered with fringed leaf-like parts called bracts) will appear on the cotton plant. As this square develops, the bud swells and begins to push through the bracts until it opens into an attractive flower. Within three days, the flower will pollinate (the transfer of pollen from the anther to the stigma of the same or another flower) itself, change from a creamy white or yellow color to a pinkish red, and then wither and fall, exposing a small, green, immature cotton boll (a segmented pod containing 32 immature seeds from which the cotton fibers will grow). This boll is considered a fruit because it contains seeds. As the fibers continue to grow and thicken within the segmented boll, it enlarges until it becomes approximately the size of a small fig. Now, the cotton fibers have become mature and thickened with their primary growth substance, cellulose (a carbohydrate, the chief component of the cell wall in most plants). An average boll will contain nearly 500,000 fibers of cotton and each plant may bear up to 100 bolls.

In about 140 days after planting or 45 days after bolls appear, the cotton boll will begin to naturally split open along the bolls segments or carpels and dry out, exposing the underlying cotton segments called locks. These dried carpels are known as the bur, and it's the bur that will hold the locks of cotton in place when fully dried and fluffed, ready for picking.

The growth cycle of the various cotton species vary in length, but the sequence of fruit production remain the same. Weather, insects and moisture can adversely affect optimum conditions for plant growth and it is the farmer's responsibility to adjust to these conditions to optimize yield.