Cotton has an indeterminate growth habit and can grow very tall under conditions of unrestrained growth. Growth regulators, such as Mepiquat chloride, are generally applied to cotton to slow internode elongation, especially for well-fertilized irrigated cotton. Otherwise, vigorous cotton varieties with plenty of water and nutrients can develop very tall, heavy vegetative growth. This type of rank growth promotes boll rot and fruit abscission, and makes a cotton crop difficult to harvest.

Figure 1. Cotton can grow very tall if its growth is not held in check by environmental factors or management practices.

The first vegetative structures that appear on the main stem are main stem leaves. Main stem leaves and branches form at points of attachment on the main stem called nodes. As a general rule, a new node is produced from the apical meristem an average of every 3 days, although nodes develop more quickly early in the growing season than later in the season.

Figure 2. Growth of a fruiting branch from the main stem. The branch forms in the axil above a main stem leaf. The leaves and stems on nodes above and below the one illustrated have been removed.

The stem-like structure that connects the leaf with the stem is called a petiole. Leaves that arise directly from the main stem are referred to as main stem leaves, while leaves that arise from the fruiting branch are referred to as subtending leaves. The fruit produced by a branch will primarily receive carbohydrates produced by the leaf subtending that fruit. However, the main stem leaf also supplies carbohydrates for fruit development. Fruit produced closer to the main stem will receive more carbohydrates from the main stem leaf than fruit produced at more distal positions.

A fruiting bud, called a square, begins to form at the initiation of the fruiting branch. The first square produced on a fruiting branch is referred to as a first-position square. As this square develops, the portion of the fruiting branch between the main stem and the square also elongates. This portion of the fruiting branch is also called the internode, similar to the portion of the main stem between main-stem nodes. An axillary meristem also develops adjacent to this square. The axillary meristem produces a second position square and subtending leaf. As many as four squares may be produced in this fashion on a fruiting branch.

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