CBSE Class 4 Science Habitat and Adaptation in Plants Notes Set 01

Habitat and adaptation

The place where a living thing naturally lives is called its habitat. A habitat gives the organism food, water, air and shelter. The special features that help an organism live well in its habitat are called adaptations.

Two groups of plants

According to where they grow, plants are put into two broad groups: aquatic plants, which grow in water, and terrestrial plants, which grow on land.

Aquatic plants

1. Emergent plants: their roots are fixed in the soil of shallow water, while the stems and leaves rise above the surface. Examples: bulrush and sedge.
2. Fixed plants: their roots are fixed in the bottom of the pond or lake and the leaves float on the surface. They have long, thin, hollow and light stalks, and the leaves have a waxy coating. Stomata are on the upper side of the leaves. Examples: lotus and water lily.
3. Underwater plants: they grow completely under the water. Their leaves are thin, narrow and ribbon-like, so water currents do not tear them. Examples: hydrilla and pondweed.
4. Floating plants: they float on the water. Their stems are light and spongy and they have no fixed roots. Examples: duckweed and water hyacinth.

Terrestrial plants

1. Desert plants (xerophytes): they live in hot, dry places. A cactus has a thick, fleshy, green stem that stores water and makes food. Its leaves are changed into spines, which protect the plant and reduce water loss.
2. Mountain plants: they live where it is very cold. Pine, cedar and spruce trees are tall, straight and cone-shaped, so snow slides off the branches. Their leaves are needle-shaped with a waxy coating.
3. Plains plants: they must survive both hot and cold weather. Examples are mango, banyan and teak. Deciduous trees shed their leaves in autumn and grow them again in spring, while evergreen trees keep dropping and growing leaves all through the year.
4. Marsh plants: mangroves grow in marshy areas. Their roots come out above the mud and are called breathing roots.
5. Forest plants: they grow tall and have broad leaves in large numbers to catch sunlight. Examples: mahogany and redwood.
6. Coastal plants: they can live in salty water and heavy rain. The coconut tree is an example.

Some special plants

Insectivorous plants trap insects to get the nutrients that poor soil cannot give them. The Venus flytrap has two lobes with hair-like spikes that snap shut on an insect. The pitcher plant has a pitcher-shaped leaf with slippery edges, so insects slip in and get trapped.

Non-green plants have no chlorophyll, so they cannot make food. They take food from dead plants and animals. Examples: coralroot and Indian pipe.

Parasitic plants grow on other plants and take food from them. Examples: cuscuta and mistletoe.

Key points

1. Habitat is the natural home of an organism.
2. Adaptations help organisms survive in their habitat.
3. A broad leaf would lose too much water in a desert, which is why desert plants have spines.
4. Plants that cannot make their own food depend on other living things.

Worked examples

Example 1. Why do desert plants have thick, fleshy and green stems? Answer: the thick stem stores water, and the green colour shows chlorophyll, which is needed to make food.

Example 2. Why are pine trees cone-shaped? Answer: in snowy places the snow slides down the sloping branches, so the branches do not break under its weight.

Example 3. Classify the following: duckweed, lotus, hydrilla, bulrush. Answer: duckweed is floating, lotus is fixed, hydrilla is underwater and bulrush is emergent.

Quick Check Questions