phototropism

American  

[foh-to-truh-piz-uhm, foh-toh-troh-piz-uhm] / foʊˈtɒ trəˌpɪz əm, ˌfoʊ toʊˈtroʊ pɪz əm /

noun

Botany.

1. phototropic tendency or growth.

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phototropism British  

/ ˌfəʊtəʊˈtrəʊpɪzəm /

noun

1. the growth response of plant parts to the stimulus of light, producing a bending towards the light source

2. the response of animals to light; phototaxis

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phototropism Scientific  

/ fō-tŏt′rə-pĭz′əm /

1. The growth or movement of a fixed organism toward or away from light. In plants, phototropism is a response to blue wavelengths of light and is caused by a redistribution of auxin from the illuminated side to the darker side of the shoot, resulting in quicker growth on the darker side and bending of the shoot toward the source of light. Certain sessile invertebrates also exhibit phototropism.

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Other Word Forms

• phototropic adjective

Etymology

Origin of phototropism

First recorded in 1895–1900; photo- + -tropism

Explanation

In biology, phototropism is the tendency of plants to move in response to a source of light. If you've ever planted a sunflower and watched it gradually turn to face the sun, you've seen phototropism in action! Phototropism describes any type of motion that organisms make in response to light, whether they seem to stretch and reach toward it, like sunflowers and other plants, or curl back away from it, like some vines tend to do. Phototropism combines the Greek photo, or "light," and tropism, "tendency of an animal or plant to move in response to a stimulus," from the Greek tropos, "a turning."

Example Sentences

Most plants show phototropism -- the ability to grow toward a light source.

From Science Daily • Oct. 31, 2023

The leaning effect could be a result of phototropism, where plants naturally position themselves toward sunlight.

From Washington Post • Aug. 2, 2022

If the tree has grown at a slant all its life, it’s probably because of phototropism, Brosius says.

From Washington Post • Aug. 2, 2022

However, of all responses controlled by phototropins, phototropism has been studied the longest and is the best understood.

From Textbooks • Jun. 9, 2022

Thus the term phototropism means a turning or orientation brought about by means of light.

From Being Well-Born An Introduction to Eugenics by Guyer, Michael F.