Why Are Plants Green?
Today is the anniversary of the death of the French botanist and physiologist Henri Dutrochet.
After studying the movement of sap in plants in his home laboratory, Dutrochet discovered and named osmosis. Dutrochet shared his discovery with the Paris Academy of Sciences on October 30th, 1826.
Like the cells in our own human bodies, plants don’t drink water; they absorb it by osmosis.
Dutrochet also figured out that the green pigment, chlorophyll, in a plant is essential to how plants take up carbon dioxide. Photosynthesis could not happen without chlorophyll, which helps plants get energy from light. And chlorophyll gives plants their color. Have you ever asked yourself why plants are green? Long story short, chlorophyll reflects green light, which makes the plant appear green.
Dutrochet was a true pioneer in plant research. He was the first to examine plant respiration, light sensitivity, and geotropism (How the plant responds to gravity, ie, roots grow down to the ground.)
The upward growth of plants against gravity is called negative geotropism, and the downward growth of roots is called positive geotropism. The plant part that responds to positive geotropism is at the very end of the root, and it is called the root cap. So, what makes the roots turn downward as they grow? The root cap - responding to positive geotropism.