goods. Cotton grows on shrublike
plants. Cotton plants belong to the mallow
family, which also includes hollyhock
and okra.
Where Cotton Grows
Cotton plants grow in warm areas in
many parts of the world. Some of the
top cotton-growing countries are China,
the United States, Pakistan, India, and
Uzbekistan.
Physical Features
In the wild, cotton plants may reach a
height of 20 feet (6 meters). As a crop,
cotton plants grow only 3 to 6 feet (1 to
2 meters) high.
Cotton plants produce white flowers
that turn red and then fall away. The
Women and children carrying goods on
their heads show a traditional side of life in
Cotonou, Benin.
The boll weevil
is the most
troublesome
pest that
attacks cotton.
Boll weevils
destroy cotton
bolls.
BRITANNICA STUDENT ENCYCLOPEDIA Cotton 205
flowers leave behind a green pod, or
fruit, called a boll. Inside each boll are
20 to 40 seeds. White fibers, which grow
from the seeds’ skins, surround the
seeds. Eventually, the bolls burst open to
reveal the fibers inside.
Different kinds of cotton plant produce
fibers of different lengths. The longest
fibers may be 2.5 inches (6.5 centimeters)
long. These fibers go into the finest
cotton cloth. Most cotton fibers are
closer to 1 inch (2.5 centimeters) long.
Processing
Before cotton fibers may be made into
cloth, they need to be cleaned and
ginned. In ginning, a machine separates
the fibers from the seeds. Next, a
machine cards the fibers, or combs
them into the same direction. Machines
then pull and twist the fibers into long
strands, called yarn. The yarn may be
treated with chemicals, dyed, or
combined with other types of fiber.
Finally, a machine weaves the yarn into
cloth.
Uses
Cotton is one of the most popular fibers
worldwide. People use it to make clothing,
sheets, towels, carpets, sails, and
many other textiles, or cloth goods. Cotton
cloth may be light or heavy. It is
easily washable and comfortable to wear.
People use cottonseeds to make oil for
cooking, cosmetics, and soap. Livestock
eat cottonseeds and the leftover parts of
cotton plants.
History
People in ancient India, China, and
Egypt grew and used cotton. Early
peoples in the Americas also grew cotton.
Arab traders brought cotton to
Europe by about AD 1000.
Cotton was difficult to process until
1793, when U.S. inventor Eli Whitney
created the cotton gin. This machine
separated cotton fibers from the seeds.
Farmers in the U.S. South soon produced
more cotton than ever before.
#More to explore
Fibers • Plant • Textile • Whitney, Eli
Cough
A cough is a sudden burst of air out of a
person’s lungs. Coughs happen when
something irritates, or bothers, the respiratory
system. The respiratory system is
the group of organs that allows people to
breathe.
Materials that cause a cough come from
various places. Smoke, dust, chemicals,
A harvesting machine gathers the puffy
buds of the cotton plant.
206 Cough BRITANNICA STUDENT ENCYCLOPEDIA
and pollution in the air all can trigger a
cough. Illnesses such as colds, influenza,
and pneumonia also can cause a cough.
These illnesses cause parts of the respiratory
system to make more of a thick,
sticky fluid called mucus. The mucus
builds up and makes it harder to
breathe. Coughing brings the mucus up
and out of the mouth. Mucus may also
drip down the back of the throat from
the nose. Coughing helps to clear this
mucus from air passages.
Coughing is good for the body. It is the
body’s way to get rid of anything in the
respiratory system that does not belong
there. However, a cough that does not
go away may be a sign that the person
has a serious disease.
#More to explore
Cold, Common • Respiratory System
Country
A country is land that is controlled by a
single government. Countries are also
called nations. Countries can be large or
small. Australia, Brazil, Canada, China,
Russia, and the United States are large
countries spread over millions of square
miles. The world’s smallest country,
Vatican City, covers less than 1 square
mile (2.6 square kilometers).
A country’s land does not have to be
connected. For example, the U.S. states
of Alaska and Hawaii are separated from
the other 48 states but are still part of
the country. Some countries are made
up of groups of islands. Indonesia and
the Philippines are examples of island
countries.
In some countries nearly all the people
belong to a single ethnic group. These
people are united by a shared history
and culture. Denmark, Norway, and
Sweden are examples. But other countries
are made up of many different ethnic
groups. Except for the Native
Americans, the United States is made up
of immigrants, or people who came
from other countries. China and India,
each with more than a billion people,
have many different ethnic groups.
A cough may be a sign of a cold or other
illness.
The flags of many countries fly outside the
United Nations building in New York City.
BRITANNICA STUDENT ENCYCLOPEDIA Country 207
Most countries are divided into smaller
parts called states or provinces. A state
has its own government. The country’s
government shares power with the state
governments. The laws made by the
country’s government affect all the
