Cotton is produced by small trees and shrubs of the genus Gossypium, of the family Malvaceae, which also includes hibiscus, okra, and the swamp mallow. The plant grows upright and has branches spreading in all directions. It has broad leaves with three to five lobes, and a taproot that may grow as deep as 4 feet into the ground.

White flowers blossom from the squares (buds) approximately five to seven weeks after planting. The flowers open in midmorning and begin to wither the next day. They turn pink, blue, and finally purple as they dry and fall off the plant. The flowers must be pollinated during the few hours they remain open. Cotton flowers usually pollinate themselves.

At first, only one or two flowers open each day. The first flowers bloom low on the plant, near the main stem. As the plant become larger, several flowers open daily. These flowers open higher on the plant and farther out on the branches. Flowering starts in summer and may last until the autumn frosts.

The boll, which contains the cotton fibers, begins to form while the flower withers. A boll matures in 45 to 60 days, during which time it grows to about the size of a golf ball. At full size, it is green and almost round, with a pointed tip. At this stage, the boll cracks in four or five straight lines from the tip. Then it splits open, showing four or five locks (groups of 8 to 10 seeds with fibers attached). The open dried boll, which holds the fluffed-out cotton, is called the bur. An average boll will contain nearly 500,000 fibers of cotton and each plant may bear up to 100 bolls.