September 27, 2026, 10:48 am | Read time: 5 minutes
When you think of the great outdoors, you usually envision green. Green forests, green flower meadows, or grassy green hills. But why are plants actually green? The answer lies partly in a pigment that everyone has probably heard of in biology class: chlorophyll. However, there’s much more behind the green color of plants. myHOMEBOOK spoke with an expert about this.
Follow myHOMEBOOK on WhatsApp now
Why We See Plants as Green
The reason most plants appear green to us is related to how they absorb sunlight. Visible light consists of different colors or wavelengths. “The chlorophyll molecules contained in the chloroplasts of plants absorb high-energy blue and lower-energy red light,” explains plant physiologist Prof. Dr. Reimund Goss from Leipzig University. Green light, on the other hand, is only very weakly absorbed by chlorophyll. The plant primarily absorbs blue and red light, while a large portion of the green light is reflected. This reflected light reaches our eyes, making the plant appear green. According to Goss, there’s an additional effect: the human eye is particularly sensitive to green light.
Plants Need Chlorophyll
Chlorophyll not only makes plants look green but also plays a crucial role in photosynthesis. Chlorophyll molecules can absorb light energy and transfer it within the photosynthesis apparatus. This is possible due to their unique chemical structure. According to Goss, chlorophyll has a ring system similar to that of hemoglobin. However, instead of iron at its center, it contains magnesium. Special chlorophyll-a molecules can use the absorbed light energy to release an electron. The subsequent processes help the plant provide the energy needed for photosynthesis and convert carbon dioxide into sugar. Additionally, water is split, and oxygen is produced.
Wouldn’t Black Plants Be More Efficient?
This raises the question: If plants need light as an energy source, why don’t they just absorb as much of it as possible? Wouldn’t black plants have an advantage? Not necessarily, because according to Goss, a plant doesn’t need to absorb every bit of light to efficiently perform photosynthesis. Absorbing blue and red light is usually sufficient.
In fact, too much light can even become a problem. If a plant absorbs more light energy than it can process, so-called reactive oxygen species, or ROS, can form. These can damage the plant. Therefore, plants have various protective mechanisms. The idea of very dark leaves isn’t entirely far-fetched. They do occur in nature. Sun leaves on the outer part of a tree crown, for example, can be very dark green. There, many chlorophyll molecules can be densely packed, allowing more green light to be absorbed.
Why Aren’t All Leaves the Same Shade of Green?
When comparing different plants, it’s quickly apparent that not all greens are the same. Some leaves appear almost yellowish, while others are distinctly dark. There are several reasons for this. Plants contain both chlorophyll a and chlorophyll b. According to the expert, chlorophyll a is blue-green, while chlorophyll b is olive green. The amount and distribution of chlorophyll also affect leaf color. This is particularly evident in sun and shade leaves. Sun leaves can contain large amounts of chlorophyll, densely packed, making them appear dark green. Shade leaves, on the other hand, have lower chlorophyll concentrations and can appear lighter.
Leaf Color Can Reveal Information About the Plant
If the usual green suddenly changes, it’s worth taking a closer look. Yellow leaf spots can occur, for example, when chlorophyll is damaged by stress. A lack of certain nutrients can also play a role. If nitrogen, magnesium, sulfur, or iron are missing, chlorophyll formation can be impaired. Yellow leaf areas are referred to as chlorosis. Brown spots can occur when leaf areas or entire leaves die. Thus, the color of a leaf can indeed provide clues that something might be wrong with the plant.
Why Do Leaves Turn Yellow and Red in Fall?
In the fall, the green color disappears in many plants. Chlorophyll is deliberately broken down. This reveals pigments that were partly hidden in the leaf all along, such as yellow and orange carotenoids. In the green summer leaf, they are visually overshadowed by the higher concentration of chlorophyll. They also perform important functions, such as protecting the leaf. Red or bluish anthocyanins are also present. These can already exist or be newly formed in higher concentrations in the fall. Therefore, leaves can turn not only yellow but also orange, red, or even violet in the fall, explains Goss.
4 Mistakes That Cause Yellow Leaves on Geraniums
Why Does My Basil Have Black Spots?
How Do Red Plants Perform Photosynthesis?
There are numerous plants with red or purple leaves where hardly any green is visible at first glance. “For photosynthesis, chlorophyll is always necessary and always present, even if it is sometimes not visible due to being covered by other pigments,” explains the plant physiologist. In red or purple plants, these are often anthocyanins. The chlorophyll is still present and can absorb light for photosynthesis.
There Are Also Plants Completely Without Chlorophyll
There are remarkable exceptions. Some plants have evolved a lifestyle where they no longer need to produce organic compounds through photosynthesis, such as the ghost plant, which can be completely white. It obtains organic compounds through fungi. Similar strategies are found in the red-brown orchid and the dodder, which parasitizes host plants. Goss explains that such plants do not need chlorophyll for photosynthesis and can indeed do without the typical green.