Plant life
There are 400,000 identified species of
plant in the world. From the tallest
redwood tree to the smallest duckweed,
and the plainest moss to the most exotic
orchid, plants all play a vital role in
sustaining life on Earth.
The stem provides support
for the leaves and flower
head and carries water,
minerals, and food to
all parts of the plant.The main root, or taproot, anchors
the plant in the ground. Together
with the side roots, it absorbs water
and minerals from the soil.Leaves collect sunlight
and contain the tiny
structures that make
food for the plant.WHAT IS A PLANT?
A plant is an organism made up
of many cells that is able to
manufacture its own food. Most
plants do this using sunlight,
carbon dioxide, and water to make
carbohydrates.The flower contains
the reproductive parts
of flowering plants.LARGEST AND SMALLESTOThe world’s largest plant is
the giant redwood tree, at
up to 275 ft (84 m) tall with a
trunk 36 ft (11 m) in diameter.
The largest flower head is
that of the titan arum from
Sumatra, which grows to
about 10 ft (3 m) tall.PLANTS ARE ESSENTIAL FOR LIFE...O Without plants
there would be
very little oxygen
in the air for us to
breathe. Plants
help reduce the
Greenhouse Effect
( p. 78–79) by
using up some of the extra
carbon dioxide we produce.Some plants, such as daisies,
have simple leaves: a leaf
that has just one flat blade.Other plants have
compound leaves,
made up of smaller leaflets.LIVING WORLD
86O Plants and algae
form the base of most
food chains. Nearly
everything we eat
comes from plants, or
from animals that eat
plants. Animals that
eat only plants are
called herbivores.O Plants have
many other uses.
Without them
there would be no
lumber for building
or burning, and no
cotton, coal, paper,
or rubber. Many
medicines, toiletries, and
dyes also come from plants.OSome plants are too small
to see clearly without a
magnifying lens. The tiniest
flowering plant is a duckweed
known as watermeal.
A whole plant is about^1 / 32 in
(1 mm) long.