I WONDER WHY?
Why does the sunflower always face the sun?
Sunflowers
seem to follow the Sun from morning to evening. All plants show a tendency to orient itself in
response to light, which is called phototropism. It is a growth hormone called
Auxin that helps the Sunflower to exhibit phototropism. Auxin is sensitive to
sunlight, and moves away from it. So Auxin often migrates to the shaded part of
the stem. One there, Auxin stimulates the growth of the cells. This cause the
stem to become bulkier, and lean in the opposite direction i.e. towards the
Sun. As the direction of the shade changes, Auxin also shifts their position in
the stem. This keeps the sunflower always facing the sun.
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