Tropic movements

Tropic movements

Plant movements that take place along a particular direction are called Tropic movements.

These movements can be towards the direction of the stimulus or away.

The stimulus can be gravity, light, chemicals etc. 

Consider this example again;

Here, the roots grow in the direction of gravity (downwards), this is Positive Geotropism

• Positive; since the movement is towards stimulus 
• Geotropism; movement due to gravity

On the other hand, shoot grows upwards opposite to the direction of gravity, this is Negative Geotropism

• Negative; since the movement is away from stimulus
• Geotropism; movement due to gravity

Example of Phototropism:

Sunflowers grow towards the sunlight

Example of Chemotropism:

Growth of pollen tubes towards ovules in the process of reproduction in plants

Example of Thigmotropism:

Plant tendrils clinging on to a support and growing

Example of Hydrotropism:

Plants grow towards regions of having water if there is a source of water nearby

Example of Thermotropism:

The plant responds to changing temperature and the growth is impacted.

The leaves of Rhododendron start folding in cold temperatures.