Main stemThe upright stalk of the plant. It is a series of nodes with a stretch of stem between each pair.
NodeA joint of the main stem. Each node gives rise to a leaf and can give rise to a branch.
LeafCotton leaves are broad and lobed, usually with three to five lobes.
Vegetative branchBuilt like the main stem. It grows upright from one bud at its tip and carries leaves, not fruit, directly. Growers call it a monopodial branch.
Fruiting branchIt grows in a zigzag. At each joint it makes one leaf and one square, which becomes a flower and then a boll. Growers call it a sympodial branch.
Flower (bloom)A square opens into a flower about three weeks after it forms. The boll starts to grow once the flower has bloomed.
TaprootThe seedling's first root becomes the taproot, which grows straight down. Thinner side roots branch from it.
Square, boll and seed 6
Square (flower bud)The flower bud, enclosed by its bracts. One forms at each joint of a fruiting branch.
BractOne of the leaf-like parts, usually three, that wrap the square. They stay on under the boll. Their top edge is cut into long teeth.
BollThe fruit of the cotton plant, grown from the flower. It is a capsule that holds the seeds and their lint.
LockOne division of the boll, a tuft of lint with seeds inside. A boll has three to five locks.
Lint (fiber)The long fibers that grow from the seed. A cotton gin pulls them off, and they are spun into thread.
SeedEach lock holds several seeds, and every seed is covered in lint.
How this list was compiled: Every name checked on 2026-09-30 against sources read that day; a name is kept only where two of them use it: (1) National Cotton Council of America, Growth and Development of a Cotton Plant, https://www.cotton.org/tech/ace/growth-and-development.cfm; (2) O. F. Cook, Dimorphic Branches in Tropical Crop Plants: Cotton, Coffee, Cacao (US Department of Agriculture, Bureau of Plant Industry Bulletin 198, 1911, public domain), https://archive.org/details/dimorphicbranche198cook; (3) The Cotton Plant: Its History, Botany, Chemistry, Culture, Enemies, and Uses (US Department of Agriculture, 1896, public domain), https://archive.org/details/cottonplantitshiunit; (4) Wikipedia, Cotton and Gossypium (text only). The two USDA bulletins are by different authors 15 years apart and are counted separately. Hints and detail lines are in our own words. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced or copied. Licence: own work
How it works
The first drawing shows the parts of a cotton plant, with its two kinds of branch. The second enlarges what a fruiting branch carries: a square, a closed boll, an open boll and one seed with its lint.
Read the full guide
The plant
Numbers 1 to 3 are the main stem, a node and a leaf. Number 4 is the vegetative branch, low on the plant, and number 5 a fruiting branch, which zigzags. Number 6 is a flower and number 7 the taproot.
From square to lint
Number 8 is a square, the bud that comes before the flower. Number 9 is a bract and number 10 the boll that grows after the flower. Number 11 is one lock of the open boll. Numbers 12 and 13 are the lint and the seed it grows on.
To tell the two branches apart, look for bolls. A fruiting branch has one at each bend; a vegetative branch carries leaves along its length.
Square, flower, boll, open boll: the same spot on a fruiting branch goes through all four.
Questions and answers
What are the parts of a cotton plant?
A taproot, a main stem with nodes, leaves, vegetative branches and fruiting branches. Each joint of a fruiting branch carries a square wrapped in bracts, which becomes a flower and then a boll. The open boll holds locks of lint and seed.
What is a cotton boll?
The fruit of the plant, a capsule that grows after the flower. Inside are three to five locks, each a tuft of lint with its seeds. When the boll is ripe it splits open.
What is a square on a cotton plant?
The flower bud, wrapped in its fringed bracts. It opens into a flower about three weeks after it forms.
Where does cotton fiber come from?
From the seeds. Each seed in a boll is covered in long fibers called lint, which a cotton gin pulls off so they can be spun.