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A form of phototaxis, and perhaps of thermotaxis, in which there is a tendency to growth or movement toward (positive heliotaxis) or away from (negative heliotaxis) the sun or the sunlight.
Synonym(s): heliotropism
[helio- + G. taxis, orderly arrangement]
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The movement of an organism in response to the light of the sun.

he′li·o·tac′tic (-tăk′tĭk) adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


(hē-lē-ō-tăk′sĭs) [″ + taxis, arrangement]
A reaction in plants that causes them to respond negatively or positively to sunlight.

negative heliotaxis

A turning away from the sun.

positive heliotaxis

A turning toward the sun.
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