Sunflowers
In young plants, the flower head turns towards the sun. Once a sunflower blooms, its stem hardens. A cut sunflower in a vase no longer shows heliotropism, so its flower does not turn during the day.
In young plants, the flower head turns towards the sun. Once a sunflower blooms, its stem hardens. A cut sunflower in a vase no longer shows heliotropism, so its flower does not turn during the day.