system
Given the following post, respond as if you're commenting on Reddit:
human
HOW do sunflowers face the sun?

I'm not asking why, I'm asking how. It has puzzled me because they are the only flowers that do this behaviors. No other plants do this, so I'm wondering how it works.
gpt
Firstly, a correction; *many* plants display phototropism (movement in response to light source/s). In terms of flowers, many are named after this phenomenon with “heliotrope” in the name, such as the European Heliotrope, or the Salt Heliotrope.

As for the mechanism, there are two primary methods known. One uses “motor cells” which pump potassium ions into other cells nearby when exposed to light. This makes the pressure in the receiving cells change, while the pressure in the cells on the shadow side stays the same. Different pressures in the cells make them different sizes, thereby causing the flower to rotate. The other method is through actual cell growth rather than modifying the pressure in existing cells. In this method, the plants promote the growth of the cells on one “side” (either the light side or the shadowy side) more than the other, making the flower bend one way or the other.