<h3>
Heliotropism</h3>
This property of facing the sun is mostly observed in young flowerheads and generally stops once the flower starts to mature. The phenomenon of flowers following the sun across the sky is called heliotropism.
<h3>Why do sunflowers face the sun?</h3>
The obvious reason for the flower following the sun would be to maximize photosynthesis.
Each sunflower plant has only one flower on its stem. Therefore, during pollination, the plant’s only means of reproducing must get noticed by pollinators. [A pollinator is anything that helps carry pollen from the male part of the flower to the female part of the same or another flower. The movement of pollen must occur for the plant to become fertilized and produce fruits, seeds, and young plants.] Continuously facing towards the east also helps the flowers to heat up quickly.
This gives them an advantage in pollination, as warm flowers attract insects. Therefore, in the plant’s interest, the flower always faces the sun and is therefore always clearly visible to these important pollinators.
When researchers compared mature flowers facing east with flowers that they had turned to face west, they made a remarkable observation. East-facing blooms attracted five times as many pollinating insects as west-facing ones. Sunflower has a clear advantage in terms of reproduction if it faces the sun.
<h3>Why a mature sunflower <u>does not</u> track the sun?</h3>
- It is mainly young flower heads that exhibit this characteristic of heliotropism because younger flowers have green “bracts” that look like a mane.
- As sunflowers mature, this process comes to a halt. Overall growth slows, and the flower's circadian clock reacts most intensely to the sun's early morning rays than those later in the day. As a result, the blooms gradually stop tracking westward altogether.
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hope it helped
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