work to be in charge of a government.
The main way in which a political party
gains power is through the election of its
members to office. “Office” is a word for
a government position—for example,
the presidency or a seat in a legislature
(lawmaking body). In many countries
the party with the most members in the
legislature has great control over the government.
Government leaders are the most powerful
members of political parties. But
ordinary voters may belong to political
parties, too. Party members usually have
similar beliefs about the role of government
and how it should be run.
The number of political parties differs
from country to country. Some countries
have several parties, and all of them
may be represented in the government.
Many European countries have three or
more major political parties.
Other countries function with only two
major parties. In the United States the
two main political parties are the Democratic
Party and the Republican Party.
Other parties, called third parties, may
exist in such a system. However, most
people support either of the two main
parties. It is almost impossible for third
parties to gain power.
Still other countries have one-party systems.
China, Cuba, and several African
countries have such systems. There all
members of the government must
belong to the same party. People might
form opposing parties, but their candidates
may not run for office. Opposing
parties may even be illegal. Such groups
are sometimes called underground
political parties.
#More to explore
Government • Legislature • Voting
Polk, James K.
James K. Polk was the 11th U.S. president.
During his term the United States
won a war with Mexico and gained
much land along the Pacific coast and in
the Southwest.
Early Life
James Knox Polk was born on
November 2, 1795, in Mecklenburg
County, North Carolina. He was the
eldest child of Samuel and Jane Knox
Polk. At age 11 he moved with his
In the United
States, the
Republican
Party’s symbol
is an elephant.
The Democratic
Party’s
symbol is a
donkey.
A portion of a ballot from a U.S.
presidential election shows candidates
from large and small
political parties.
114 Political Party BRITANNICA STUDENT ENCYCLOPEDIA
family to Tennessee. He graduated in
1818 from the University of North
Carolina.
Polk then returned to Tennessee and
studied law. In 1820 he started a law
practice in Columbia, Tennessee. Four
years later he married Sarah Childress.
They had no children.
Political Career
A Democrat, Polk was elected to the
Tennessee legislature in 1823. A year
later he was elected to the U.S. House of
Representatives. He served there for 14
years, including four years as speaker
(leader) of the House. In 1839 Polk was
elected governor of Tennessee. He failed
to win reelection in 1841 and again in
1843.
Presidency
The Democrats planned to choose Polk
to run for vice president in 1844. A dispute
over the presidential candidate,
however, led the Democrats to ask Polk
to run for president instead. In the election
Polk defeated Henry Clay of the
Whig Party.
As president, Polk settled a fight over the
Oregon Territory. The United States and
Great Britain both claimed the land.
November 2, June 15,
1795 1824 1839 1844 1846 1848 1849
Polk is born in
Mecklenburg
County, North
Carolina.
Polk is elected
to the U.S.
House of
Representatives.
Polk becomes
governor of
Tennessee.
Polk is elected
president.
Polk settles the
Oregon
dispute.
The Mexican
War ends;
the United
States gains
land.
Polk dies in
Nashville,
Tennessee.
T I M E L I N E
James K. Polk was the 11th president of the
United States.
BRITANNICA STUDENT ENCYCLOPEDIA Polk, James K. 115
Polk proposed dividing the territory at
the line of 49° north latitude (the 49th
parallel). After refusing, Britain finally
accepted Polk’s offer. In 1846 the
United States received the part of
Oregon south of the 49th parallel.
Polk also gained Texas and much of the
Southwest for the United States. In
1845 the United States admitted Texas,
formerly part of Mexico, as a state. That
action caused the MexicanWar of
1846–48. After the United States
defeated Mexico, it bought more Mexican
land. That territory included parts
of what are now Arizona, California,
Colorado, Nevada, New Mexico, and
Utah.
Retirement
At the end of his term in 1849, Polk
retired to his home in Nashville, Tennessee.
He died soon afterward, on June 15,
1849.
#More to explore
MexicanWar • Oregon • United States
Pollen
Pollen is the substance that causes plants
to form seeds. New plants then can grow
from the seeds. Both flowering plants
and conifers (plants that grow seeds
inside cones) make pollen. A grain of
pollen is so tiny that it is best viewed
through a microscope.
Pollination
The male parts of a plant, called stamens,
make pollen grains. These grains
contain sperm cells. The female parts of
a plant, called pistils, contain egg cells.
During pollination, pollen grains travel
from the male parts to the female parts.
There, a sperm cell from the pollen joins
with an egg cell. The fertilized cell then
develops into a seed.
Some plants have only male or only
female parts. They need help transporting
