As the sun rises each day it casts its warm rays across the landscape. Every tree the light touches will reflect back a dazzling array of green. During the summer months, in particular, these seas of green are mesmerising. Yet, have you ever stopped to wonder why trees come in so many different shades of green?
Recently, a guest asked me this question and while it mostly comes down to the pigments in the leaves, it’s a little more complex than the biology lessons on photosynthesis and chlorophyll that I could remember. So with the lush green abundance that currently surrounds us, I thought it was a topic worth re-exploring.
Where does the colour green come from?
The green colour in leaves is due to the presence of chlorophyll, a pigment that absorbs sunlight energy, which in turn is used to make food through the process of photosynthesis. While this part of the process is more familiar, it is actually the molecular properties of chlorophyll that absorb and reflect certain wavelengths of natural light which leads us to see leaves as green. As light hits a leaf, the chlorophyll absorbs wavelengths from the blue and red regions of the visible spectrum and reflects wavelengths in the green, yellow, and orange spectrum in varying degrees back into our eyes. The Greek roots of the word chlorophyll are thus chloros meaning green and phyllon meaning leaf.
Why are there different shades of green?
Not only does the amount of chlorophyll in a leaf affect the shade of green, but I was surprised to learn that there are actually 6 broad categories of chlorophyll. However, I will keep it simple here as plants mostly have only two types of chlorophyll in them:
The primary pigment involved in photosynthesis and is found in all photosynthetic organisms. It absorbs light most efficiently in the blue and red wavelengths and reflects light in the green wavelength resulting in slightly more yellow-green shades.
A small female often found in NW Marthly. Similar spot pattern to her mother the Ingrid Dam Female.
A secondary pigment that is found in some plants, algae, and cyanobacteria. It is not as efficient at absorbing light as chlorophyll A and it differs by absorbing light in the blue and green wavelengths and reflecting light in the yellow and red wavelengths. This results in darker shades of blue-green leaves.
While the amount and combination of these two types of chlorophyll will result in varying shades of green, there are also other pigments called carotenoids, anthocyanins, flavonoids, and xanthophylls that contribute to the overall colour of the leaves. These pigments produce yellows, oranges, reds, blues, and purples which not only influence the shades of green but are also responsible for the bright colours we see in flowers, fruits, and vegetables.
The Dudley Riverbank female was another successful cub of the 3:4 female that reached old age, eventually passing away at just over 17 years
What else can influence the shades of green?
The shades of green that we see in plants are also influenced by the habitat in which they grow. Different habitats have different light levels, temperatures, and soil conditions, all of which can affect the chlorophyll concentration and contribute to the wide range of shades of green that we see in plants.
- Light: The intensity and quality of light can affect the colour of a plant. For example, plants exposed to full sunlight may have deeper green or red colours than those grown in the shade because they can produce more chlorophyll.
- Temperature: Cool temperatures can cause some plants to develop reddish or purplish colours, while warm temperatures may cause them to become more yellow or green.
- Soil: The nutrients and pH of the soil can influence the colour of a plant. For example, iron deficiency can cause a plant to become pale or yellow, while an excess of iron can cause the leaves to turn yellow or brown.
- Age: As plants age, their colour may change. For example, the leaves of some plants may turn yellow or red as they mature.
- Drought: Drought stress can cause a plant to lose its color, especially in its leaves. This is because the plant is not able to produce as much chlorophyll, which is necessary for photosynthesis.
Although, pigments might be the foundation of the summer shades of green and the golden autumn hues, diving deeper into some of the more technical chemistry and understanding that each plant has evolved to adapt to its environment in its own unique way gives us a greater appreciation of the beauty and diversity of the natural world. Whether it is the deep emerald green of a mahogany tree or the vibrant green of the bushwillow trees, the shades of green are also a testament to the adaptability and resilience of trees and a symbolic reminder of growth, renewal, and prosperity.