What is chlorophyll?
Chlorophyll is the pigment that gives plants their typical green color. The term comes from Greek: "chloros" means green and "phyllon" leaf, so together it means "green leaf." This leaf pigment is found in almost all green plants as well as in many algae. Several types of chlorophyll are distinguished:
- Chlorophyll a: blue-green, the main pigment in all plants, algae, and cyanobacteria
- Chlorophyll b: yellow-green, in green algae, euglenophytes, and all land plants
- Chlorophyll c: yellowish-green, in brown algae, diatoms, golden algae, and coccolithophores
- Chlorophyll d: olive green, in red algae and some cyanobacteria
- Chlorophyll f: greenish, in specific cyanobacteria, e.g., stromatolites
In houseplants, you primarily find chlorophyll types a and b, which ensure that the plants can grow well even under indoor light conditions.
Chemical structure of chlorophyll
Chemically speaking, chlorophyll is a so-called chelate complex: A magnesium ion sits in the center of a ring-shaped molecule, the porphyrin ring, to which four nitrogen atoms are bound. A long hydrocarbon chain, the phytol side chain, anchors the molecule in the cell membrane of the chloroplasts. Interestingly, the blood pigment heme in human hemoglobin has a very similar ring structure—except that instead of magnesium, an iron ion sits in the center.
Why leaves appear green
Although sunlight consists of many colors, chlorophyll primarily absorbs red and blue light and reflects mainly green light. That is why leaves appear green to our eyes. Throughout the year, the amount of this pigment in the leaves changes. Especially in autumn, chlorophyll is broken down, allowing other pigments such as carotenoids and anthocyanins to become more visible, causing the typical autumn coloration.
Why chlorophyll is important for plants
Only through chlorophyll are plants able to perform photosynthesis—that is, to convert light energy into vital substances. Chlorophyll a is the main pigment that converts light energy directly into chemical energy. Chlorophyll b supports this as an auxiliary pigment by making additional light spectrums usable.
Influence on plant health
The amount and activity of chlorophyll also determine how efficiently a plant can perform photosynthesis. Plants with many large, dark green leaves can use more sunlight, while species with smaller or lighter leaves often have lower photosynthetic performance. Environmental factors such as light intensity, temperature, and nutrient supply can also influence the formation of chlorophyll.
The concentration of chlorophyll in the leaf is also an important indicator of the plant's state of health. A vibrant green usually indicates a good nutrient supply, while pale or yellow leaves can point to nutrient deficiency, drought stress, or diseases.
Recognizing chlorophyll deficiency (chlorosis)
If a plant produces too little chlorophyll, this is referred to as chlorosis. It is typical for the leaves to appear pale, yellowish, or even whitish, while the leaf veins often remain green in the case of an iron deficiency. Common causes are a lack of magnesium or iron, locations that are too dark, root damage due to waterlogging, or a high pH value in the substrate, which blocks nutrient absorption. If the cause is remedied, chlorophyll production can usually normalize again.
Chlorophyll gaps: What lies behind variegated plants
Variegated plants have leaves that show both green and light or white areas. The green surfaces contain chlorophyll and are responsible for photosynthesis. The light or white sections, on the other hand, contain no or very little chlorophyll and therefore cannot convert sunlight into energy. As a result, variegated plants generally have a lower photosynthetic performance than purely green plants and usually grow a bit slower. For their development, they are therefore particularly dependent on good light conditions, though without direct, strong sunlight, as the white leaf areas are particularly sensitive to sunlight.
What is chlorophyll made of?
Chlorophyll consists of a ring-shaped porphyrin molecule with a magnesium ion in the center, as well as a long hydrocarbon chain that anchors the molecule in the cell membrane.
Is chlorophyll the same as photosynthesis?
No. Chlorophyll is the pigment that absorbs light energy. Photosynthesis is the entire chemical process in which this light energy, along with water and carbon dioxide, is converted into sugar and oxygen.
What happens when there is a chlorophyll deficiency?
If a plant lacks chlorophyll, the leaves turn pale, yellowish, or whitish, and photosynthetic performance decreases. This is known as chlorosis, which is usually caused by nutrient deficiency, insufficient light, or root problems.
Why is chlorophyll green?
Chlorophyll absorbs mainly red and blue light and reflects green light. We perceive this reflected green light, which makes leaves appear green.
