Tropic Movements in Plants: Meaning of Tropic Movements, Types of Movements

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Meaning of Tropic Movements

  • The directional movement of parts of plants in response to environmental stimuli.

  • Plants react to environmental stimuli such as touch, light, water, gravity, etc.

  • The movements are slow.

    • Either towards the stimulus.

    • Away from it.

  • If a plant moves towards the stimulus, a stimulus would be positive.

  • If a plant moves away from the stimulus, the stimulus will negative.

Movements in Plant

Movements in Plant

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Types of Movements

Types of Movements

Types of Movements

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Phototropism

  • This movement occurs in response to light.

  • Plants grow either towards or away from the light.

  • The stems show positive phototropism.

  • The roots show negative phototropism.

Gravitropism/ Geotropism

  • Plants show some plants show some growth in response to gravity.

  • The stem grows along the upward direction showing a negative geotropism.

  • The roots grow in the downward direction indicating a positive geotropism.

  • In case of prostrate plants:

    • Stems lose their negative geotropism.

    • Develops into tubers or rootstock.

Chemotropism

  • This tropism takes place in reaction to chemical stimuli.

  • It is very common in case of flowering plants.

  • Some of the examples are:

    • Tentacles movement in Drosera.

    • The movement of pollen tube towards the ovary.

    • Conversion of a flower into fruit.

Thigmotropism/Haptotropism

  • It is the growing or the developing movements made through plants in response to contact with a solid object.

  • The tendrils and twiners usually show these movements.

  • This movement is also common in money plants, green peas, etc.

Hydrotropism

  • This movement is in relation to the stimulus of water.

  • The equivalent response to the stimulus of water is known as hydrotropism.

  • The roots show the positive hydrotropic response.

    • Moving and growing towards the water.

Thermotropism

  • This is the response towards a change in atmospheric temperature.

  • Some of the examples:

    • The curling of leaves in Rhododendron.

    • The curling of leaves in Mimosa pudica leaves.

FAQs

Q 1. List some the external factors supporting Tropic movements.

Answer: Some of the external factors supporting tropic movements are light, gravity, temperature, water, etc.

Q 2. What are the six types of movements in Plants?

Answer: The six types of movements in Plants are namely Phototropism, Gravitropism, Chemotropism, Thigmotropism, Hydrotropism, Thermotropism.

Q 3. Explain any three directional movements in Plants.

Answer:

i) Phototropism-a reaction to light.

ii) Geotropism- a reaction to gravity.

iii) Thermotropism-a reaction to the change in temperature.