Adaptation Of Plants

Definition

The term adaptation is derived from latin word ‘adaptare’ which means ‘to fit’.

Adaptation is the adjustment or changes in behavior, physiology and structure of an organism to become more suited to an environment. Plants have adaptations to help them live and grow in different areas. Adaptation explains why certain plants are found in one area but not in another.

For example, cactus are not found in Arctic and tall trees are not seen in grassland.

Types of Adaptation

There are 3 main types of adaptations found in organisms:

  1. Structural adaptation: When structures are built or made in organisms to adapt with their environment then it is called structural adaptation.
  2. Physiological adaptation: When physiological functions are developed or modified in organisms to adapt with environment then it is called physiological adaptation.
  3. Behavioral adaptation: The acts of organisms done naturally or by instinct are known as behavioral adaptation.

Structural Adaptation

  • Adaptation to get food

– Leaves and stems absorb energy from the Sun.

  • Adaptation to get water and nutrients

– Roots soak up water and nutrients from the soil

  • Adaptation for reproduction

– Sweet fruit attract animals that spread seeds far away.

– Some seeds are shaped to catch the wind.

– Brightly colored flower with nectar attracts pollinators such as birds, bees and insects.

  • Adaptation for defence

– Spines and thorns protect plants from predators.

– Poison lvy and Poison oak have toxins that give predators a painful itchy rash.

Physiological Adaptation

  • Photosynthesis in stems when no leaves in plants.
  • Flowers open at night when cooler.
  • Organisms gain resistance against antibiotic or pesticides.

Behavioural Adaptation

  •   Adaptation to get food

– Plants like the venus fly trap, trap insects for food.

– Plants lean or grow towards the Sun.

– Roots grow down into soil.

– Vines climb up trees to catch Sunlight.

  • Adaptations to get water and nutrients

– Desert flower can stay dormant for months, only coming to life when it rains.

  • Adaptation for reproduction

– Plant drop seeds for new offspring.


Classification on water availability

Plants can be classified into the following types based on their adaptation to availability of water:

  1. Hydrophytes
  2. Hygrophytes
  3. Mesophytes
  4. Xerophytes
  5. Halophytes

1. Hydrophytes

The plants which grow in water partially or completely are known as aquatic plants or hydrophytes. Water may be freshwater or saline water.

Example:

  • Hydrilla sp.
  • Eichhornia crassipes

Hydrophytic plant. More..

2. Hygrophytes

  • The plants of this group are invariably moisture and shade-loving.
  • Their root system and vascular tissue are poorly developed.
  • Their stem and roots are soft and spongy and show stunted growth.
  • The stem is mostly modified as underground rhizome which is also an organ for propagation.
  • The leaves are well developed and prominent, provided with stomata.
  • Since these plants grow in moist and shady habitats, their rate of transpiration is very low, and the excess of water is expelled through special openings called water stomata or hydathodes.

Common examples are ferns, begonias, aroids and certain grasses.

3. Mesophytes

Mesophytes are plants that are able to grow and thrive under typically average conditions. They require an average amount of water and a consistent average temperature in order to survive.

Most of the plants surrounding us are mesophytes.

4. Xerophytes

The plants which grow in xeric (dry) environment (habitat) are called xerophytes. Deserts are the best examples for xeric environment, where plant face inadequate water and high transpiration rate.

Xerophytes are classified into the following three categories-

  1. Ephemerals: These plants complete their life cycle within a short period. They are also called “drought escapers” or “drought evaders”.
  2. Succulents: These plants have succulent and fleshy organs to store high amount of water accumulated during rainy season.
  3. True xerophytes: Plants which are able to live under extreme dry conditions and high temperature.

Xerophytic plant. more..

5. Halophytes

Plants that survive in the saline condition are known as halophytes.

Since halophytes can not easily absorb water, they develop almost all important xerophytic devices for optimum use of water.

Halophytes. More..
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