If you have ever wondered why plants’ stems and leaves are green or what pigment gives plants their green color, keep reading because we will cover everything from the genesis of green plants to why plants are green and the variations that color experiences in them at different times of the year.
The Origin of Green Plants
To begin with, terrestrial plants developed from plant creatures that arose and evolved underwater. Aquatic photosynthetic bacteria and algae come in various colors, including green, yellow, red, and brown. So, what causes the color green to prevail in terrestrial plant leaves? The most widely held belief is that plant species have developed their photosynthetic systems to collect photons of light since it is abundant on land.
However, the light intensity has not always been the same on Earth, i.e., the number of photons incident on Earth has changed over history (luminosity increased dramatically at the beginning of Earth’s history).
Furthermore, light filtering by the atmosphere before it reaches the Earth’s surface varies with its chemical makeup, mainly due to ozone and oxygen (two components that were not present in the primordial atmosphere). Finally, we must examine the effect of water filtration on the light that reaches different depths.
Why Plants are Green in Color
The sunlight that reaches Earth is high in red photons and low in blue photons, which have the maximum energy in the spectrum. Greenlight photons are in an energetic intermediate position. These photons are likewise in short supply in the sunshine.
Most plants have chloroplasts, which contain the chlorophyll molecule responsible for catching light photons for photosynthesis and giving plants their green color. These pigments absorb the solar spectrum’s most abundant light, red, and most energetic blue while reflecting green light. This is why plant stems and leaves appear green to us.
Other stains besides chlorophyll exist. Chlorophyll pigments function similarly to antennas appropriately placed to catch photons of light from the sun. For example, photosynthetic organisms that live underwater have pigments that allow them to detect better photons of the solar spectrum that are more numerous underwater.
Because the plants that emerged from the water adapted to the more plentiful light spectrum of the terrestrial surface, we may argue that the green hue of terrestrial plants is the consequence of an evolutionary process.
Would plant leaves turn green if the Earth orbited a bright body with different properties from the Earth? No, it would not. In these instances, there would be blue or black plants, depending on whether the planet orbits a bright body of type F (which colors plants in blue) or red dwarf (which favors plants adapted to capture all types of photons, i.e., they would be black plants).
Why do Plants change Color?
Plant leaves are green because of the light spectrum absorbed and reflected by chlorophyll. On the other hand, warm temperatures and sunshine are required for chlorophyll production to proceed; otherwise, it will progressively cease to be formed.
Warm temperatures and plentiful sunshine characterize spring and summer. As a result, as the days grow shorter and the nights become longer (as is typical in autumn and winter), chlorophyll production slows until it is no longer generated. The leaf eventually runs out of chlorophyll.
As a result of this, the green color gradually fades away. The other pigments become more visible when this happens, and the leaves turn yellow, orange, brown, ocher, or red.