Adaptations in Plants Chapter Notes | Science Class 4 ICSE PDF Download

Introduction

Plants grow in different places on Earth, like land and water, and each place has unique conditions. To survive and grow well, plants develop special features called adaptations. These adaptations help them live in their specific habitats, such as plains, deserts, hills, marshy areas, coastal regions, or water bodies. This chapter explains how plants adapt to various climates, water availability, soil types, and other factors to thrive in their environments.

Adaptations to Different Habitats

Plants change their features based on the climate of their habitat.

Factors affecting plant adaptations include:

• Temperature of the area.
• Amount of rainfall and sunlight.
• Availability of water.
• Type of soil.

Plants are grouped into two types based on their habitats:

• Terrestrial plants (grow on land).
• Aquatic plants (grow in water).

Adaptations in Terrestrial Plants

Terrestrial plants grow on land and are found in places like plains, deserts, hills, marshy areas, and coastal regions.

Plants Growing in Plains

• Plains are flat, large areas with warm or hot summers and cold winters.
• Rainfall varies; some plains get heavy rain, others get less.
• Types of trees in plains:
  • Deciduous trees: Shed leaves in autumn and grow new ones in spring (e.g., sheesham, teak).
  • Evergreen trees: Do not shed leaves, stay green all year, and replace old leaves with new ones (e.g., mango, bamboo, ashoka).
• Plants in plains have many branches and leaves.

Plants Growing in Deserts

Deserts have very little rainfall and sandy soil.

Adaptations of desert plants:

• Leaves are changed into spines or thorns to reduce water loss.
• Green stems perform photosynthesis and store food and water.
  Examples: Cactus, date palm, aloe vera.

Plants Growing on Hills

Hills or mountains are cold, high areas with snowfall in winters.
Adaptations of hill plants:

• Trees have thick bark to stay warm.
• Trees are tall, straight, and cone-shaped, so snow slides off easily.
• Leaves are waxy and needle-like to prevent water loss.
• Trees are flowerless and have cones with seeds (called conifers).
  Examples: Pine, fir, deodar, spruce, cedar.

Plants Growing in Marshy Areas

• Marshy areas or swamps are wet lowlands with clayey, sticky soil.
• Plants in these areas are called mangroves.
• Adaptations of mangroves:
  • Have aerial or breathing roots that Idiomatic expression "breathing roots" is not a standard botanical term, but it likely refers to aerial roots used for gas exchange in plants. that grow above the soil to breathe air.
• Example: Grey mangroves.

Plants Growing in Coastal Areas

Coastal areas have hot, wet climates, sandy and salty soil, and strong winds.

Adaptations of coastal plants:

• Can tolerate salty soil and strong winds.
• Have many leaves and do not shed them all year.
• Fruits and seeds are spread by the sea.
  Examples: Coconut, teak, rubber.

Adaptations in Aquatic Plants

Aquatic plants grow in water and are divided into three types: floating, fixed, and underwater plants.

Floating Plants

Float freely on water surface with no fixed roots.

Adaptations:

• Light, spongy stems with air to help float.
• Waxy coating on leaves to prevent decay.
  Examples: Water lettuce, duckweed, water hyacinth.

Fixed Plants

Roots are fixed in the mud at the bottom of water bodies.

Adaptations:

• Flat, broad leaves to float on water.
• Waxy coating on leaves to prevent rotting.
• Long, hollow, light, and flexible stems to bend with water flow.
• Large leaves absorb more sunlight for photosynthesis.
  Examples: Lotus, water lily.

Underwater Plants

Grow completely under the water surface (submerged plants).

Adaptations:

• Thin, ribbon-like leaves with no stomata.
• Flexible, air-filled stems to move with water flow.
• Roots fix plants in muddy soil.
• Breathe through their body surface.
  Examples: Hydrilla, pondweed, tape grass.

Some Interesting Adaptations in Plants

Insectivorous Plants

Plants like Venus flytrap and pitcher plant trap and eat insects.

Venus flytrap:

• Small plant with leaves that attract insects.
• Leaves have stiff hairs that close when touched by an insect, trapping it.
• Plant absorbs nutrients from the trapped insect.
• Leaves close only if a different hair is touched within 20 seconds.

Pitcher plant:

• Leaves form a pitcher-like structure with a lid and fluid inside.
• Insects enter for fluid, get trapped, and are digested by plant juices.

Non-green Plants

• Plants like mushrooms, moulds, and Indian pipe lack chlorophyll.
• Cannot make food through photosynthesis.
• Absorb nutrients from other sources.

Terms to Know

• Terrestrial plants: Plants that grow on land.
• Deciduous trees: Trees that shed leaves once a year.
• Evergreen trees: Trees that stay green all year.
• Desert: Dry, sandy area with little rainfall and few plants.
• Marshy area/Swamp: Wet or flooded land with clayey, sticky soil.
• Coastal area: Land near the sea.
• Aquatic plants: Plants that grow in water.