Britannica Student Encyclopedia - 2010

aged and poor African Americans. Harriet

Tubman died in Auburn on March

10, 1913.

#More to explore

African Americans • American CivilWar

• Slavery • Underground Railroad

Tubman was

called “the

Moses of her

people”

because she

led black

people to

freedom.

(Moses led

the Jewish

people to

freedom in

ancient times.)

Harriet Tubman

BRITANNICA STUDENT ENCYCLOPEDIA Tubman, Harriet 105

 

Tulip

Tulips are plants that bloom in early

spring. The flowers are cup-shaped and

very colorful. They are among the most

popular garden flowers. There are about

4,000 varieties of tulip. They belong to

the lily family.

Tulips first grew in south-central Asia.

People brought the flowers to Europe in

the 1500s and later to many different

parts of the world. The Netherlands

became the center of tulip production in

the 1600s. It still is today.

Tulips normally grow from bulbs that

are planted in autumn. Each bulb produces

a plant each spring for a few years.

A tulip plant has two or three thick,

bluish green leaves. These are attached at

the bottom of the stem. In most types of

tulip each stem grows a single flower.

Tulip flowers occur in almost every

color—white, yellow, pink, red, orange,

purple, and even brown and black. The

color is either solid or streaked. Streaked

tulips get their streaks because of a

harmless virus. The virus makes the top

color disappear in some places. The

flower’s underlying white or yellow color

then shows through.

#More to explore

Flower • Lily • Netherlands, The

Tuna

Tuna are large fish that live in most parts

of the world’s oceans. They belong to

the same family of fish as mackerel.

Tuna is one of the most popular foods

that comes from the sea. Most of the

tuna that fishers catch is canned.

There are seven different species, or

types, of tuna: bluefin, albacore, yellowfin,

bigeye, blackfin, longtail, and southern

bluefin. The skipjack tuna is related

to these species, but it belongs to a separate

group of fish.

A tuna has a long, rounded body. It is

usually dark on top and silvery underneath.

Some species have spots or

stripes.

Many species of tuna are about 35 inches

(90 centimeters) long. The bluefin tuna

is the largest species. It can grow as long

as 14 feet (4 meters) and weigh up to

1,800 pounds (800 kilograms).

Tuna travel in large groups called

schools. Some species travel long distances.

Tuna feed on other fish, includ-

Tulips surround the trunks of birch trees. ing herring, menhaden, and mackerel.

106 Tulip BRITANNICA STUDENT ENCYCLOPEDIA

 

Some species also eat small, spineless

animals such as squid. Some types of

tuna return to the waters where they

hatched to spawn, or produce eggs.

#More to explore

Fish

Tundra

Tundras are large, barren regions with

no trees. In fact, the word tundra comes

from the Finnish word tunturia, which

means “treeless plain.” Tundras lie

between the permanent ice of the far

north and the northern forests of North

America, Europe, and Asia. They cover

about 20 percent of Earth’s surface.

Features

Tundras may be flat, hilly, or mountainous.

Little plant life grows on the bare or

rocky ground. Tundras in coastal areas

tend to be foggy. Snow covers the

world’s tundras for more than six

months of the year.

Types of Tundras

Arctic tundras lie in northern Europe,

Russia, Alaska, Canada, and Greenland.

In these tundras the winter temperature

may be as low as .25° F (.32° C). The

summer temperature may rise only to

40° F (4° C). Because of these cold temperatures,

Arctic tundras have a permanent

layer of frozen soil, called

permafrost. Some permafrost reaches as

deep as 1,500 feet (456 meters).

Alpine tundras lie farther south than

Arctic tundras. Alpine tundras are found

in high mountains above the tree line.

(The tree line is the highest place where

trees can grow.) They have short, cool

summers and less extreme winters than

Arctic tundras. Alpine tundras do not

have a layer of permafrost.

Life in a Tundra

Only low-growing plants, such as

mosses and shrubs, can survive in tundras.

Plantlike living things called

lichens also grow there.

Tundra animals must be able to survive

long, cold winters. Many birds live there

in the summer, but few stay through the

winter. Some common tundra animals

The bluefin tuna is the largest type of tuna.

Reindeer graze on the Arctic tundra of

Canada’s Northwest Territories.

BRITANNICA STUDENT ENCYCLOPEDIA Tundra 107

 

are reindeer, Arctic foxes, snowy owls,

musk oxen, and polar bears.

Very few people live in tundras. Arctic

peoples, including the Eskimo (Inuit),

tend to live in places where hunting and

fishing can provide enough food yearround.

Resources

The ground of many tundras contains

coal, oil, iron ore, lead, or other

resources. Many companies have set up

mining operations in tundra regions.

However, some people worry that mining

and oil drilling endangers tundra

plants and animals.

..More to explore

Eskimo • Lichen • Mining

Tunis

Population

(2007 estimate)

745,000

Tunis is the capital of Tunisia, a country

in northern Africa. It is the largest city

in Tunisia by far. Tunis lies near the

coast of the Mediterranean Sea. A canal

links it to a port on the sea.

Tunis is Tunisia’s center of industry.