Green is one of the most common colors found in nature. It dominates the plant kingdom due to the presence of chlorophyll, a green pigment necessary for photosynthesis. Beyond plants, many animals, insects, and other organisms have adapted the color green as camouflage, a signal, or for other evolutionary purposes. When we see the color green, it often evokes a sense of life, growth, and the natural environment.
In this article, we will explore many of the living and non-living things that exhibit the color green. Understanding what makes things green helps illuminate key scientific principles about light, pigmentation, evolution, and more. We will also appreciate the diversity and ubiquity of the color green throughout our world.
The vast majority of plants, including trees, shrubs, grasses, mosses, ferns, and most flowering plants contain chlorophyll and thus appear green. Chlorophyll is a complex molecule in plant cells that absorbs certain wavelengths of light and utilizes this energy along with water and carbon dioxide to produce sugars and oxygen through photosynthesis. This gives chlorophyll and most plant life their characteristic green pigmentation.
Some examples of green plants include:
|Conifers||Pines, firs, spruces|
|Deciduous trees||Oaks, maples, beeches, birches|
|Shrubs||Bayberry, barberry, boxwood|
|Grasses||Green grass, bamboo, sugar cane|
|Mosses||Peat moss, cushion moss, mood moss|
|Ferns||Bracken fern, sword fern, maidenhair fern|
|Flowering plants||Roses, tulips, daffodils, sunflowers|
During autumn in temperate climates, the chlorophyll in some plant leaves breaks down, allowing yellow and orange carotenoid pigments to become visible. This produces the familiar fall colors associated with the seasons changing. But in tropical and subtropical climates, plants remain green year-round.
Algae are a diverse group of aquatic organisms that also contain chlorophyll and require photosynthesis to live and grow. Most algae appear green, lending a greenish hue to bodies of water or surfaces where they proliferate.
Green algae especially abundant in ponds, lakes, and oceans where sunlight enables their growth. Some common green algae examples include:
In marine environments, immense algal growth called algal blooms can occur and are visible from space. Though small in size, the collective green pigmentation of trillions of algae tints the water green.
While most reptiles have scales with earth tones like brown, black, or grey, some prominent lizards and snakes exhibit brilliant green coloration. Reptiles are ectothermic, meaning they rely on external heat to regulate their body temperature. Thus, the green hides of reptiles serves as camouflage, blending into foliage to evade predators and surprise prey.
Some green reptiles include:
|Green anole||Small lizard with ability to change from green to brown|
|Emerald tree boa||Arboreal snake of South America|
|Green iguana||Common tropical lizard|
|Green tree python||Ambush predator snake native to Australia/New Guinea|
The green pigmentation in reptiles comes from combinations of blue, yellow, and green photoreceptor cones in their skin cells that reflect light to produce green colors. Under certain conditions like temperature changes or moods, some reptiles can change their skin from green to brown by adjusting chromatophore cells.
Many frogs and salamanders have green skin or markings that provide useful camouflage in their wetland habitats. By blending in with lilypads, grasses, bushes near shorelines, green amphibians can avoid predators and approach prey more stealthily.
Some green amphibians include:
|Green tree frog||Small frog native to southeastern United States|
|Emerald glass frog||Translucent green frog of South America|
|Green salamander||Lungless salamander species dependent on moisture|
|Mossy frogs||Frogs covered in bumps that resemble moss|
As with reptiles, the green color usually comes from a combination of blue and yellow pigments in their skin. And some frogs can adaptively change between green and brown depending on environmental conditions.
While fish come in a rainbow of colors, green is a less common hue in the aquatic vertebrates. But some species do incorporate green, often as a form of camouflage that matches the colors of the habitat.
Some green fish include:
|Green moray eel||Eel that lurks in crevices of coral reefs|
|Emerald catfish||Algae eating fish of fast moving streams|
|Green swordtail||Small freshwater fish commonly kept in aquariums|
The green tones in fish may come from reflected blue/yellow light, consumption of green algae, or thin layers of translucent skin over pigmented covers that filter light. Some fish can also change colors like flounders that adapt to match the seafloor.
A huge diversity of insects bear some degree of green coloration, including grasshoppers, praying mantises, leafhoppers, caterpillars, and more. As with reptiles and amphibians, the green hues serve as camouflage from predators against a backdrop of leaves and plants. Some insects like the green stink bug also use their color to mimic dangerous or unappealing species as further protection.
Notable green insects include:
|Praying mantis||Insect predator that blends into foliage|
|Katydid||Leaf-like appearance matches green surroundings|
|Cabbage white butterfly||Green caterpillar transforms to white butterfly|
|Green stink bug||Emits odor and mimics unappealing insects|
In some insects like caterpillars, the green comes from eating leaves and plants rich in chlorophyll. In others, biological pigments like heme, carotene, or uric acid produce the green hues.
Parrots are the most distinctly green birds due their brilliant plumage. The green in parrots stems from a unique class of pigments called psittacofulvins, molecules that reflect predominantly green and blue light. Some of the greenest parrot species include:
|Green macaw||Large parrot found in forests of Central and South America|
|Green parakeet||Small long-tailed parrot native to warmer regions|
|Budgerigar||Small green and yellow parrot known as a pet bird|
Beyond parrots, few birds are purely green. But some do contain minor green plumage like green-headed mallards or green jays that incorporate the color among vivid blues, reds, and other hues.
Unlike many invertebrates, reptiles, plants, and birds, mammals rarely exhibit a dominant green coloration. But some species do demonstrate green tints in their fur. In mammals like sloths and monkeys, the green comes from algae that grows in their fur. The algae benefits from sunlight absorbed through the translucent hairs, while the green color may provide some camouflage for the mammals.
Some greenish mammals include:
|Three-toed sloth||Fur grows green from algae|
|Pygmy marmoset||World’s smallest monkey with faint green tones|
|Cotton-top tamarin||New World monkey with hints of green fur|
A few other mammals like zebras and mice may also demonstrate some greenish fur coloring as a form of camouflage in the wild or domestication in the case of green mice bred as pets.
Beyond the major groups of plants and animals, many other living things inherit green pigmentation either from photosynthesis or as a survival adaption. Some examples include:
|Green algae||Single-celled organisms that form colonies in water|
|Euglena||Green unicellular microorganism with plant and animal traits|
|Green sea turtles||Omnivorous marine reptiles migrate long distance|
|Glass frogs||Amphibians with translucent skin|
Additionally, photosynthetic bacteria and yeast can appear green from chlorophyll-like molecules, and protists like green amoebas get their color from consuming plants, algae, or photosynthetic bacteria. Some fungi even demonstrate green spores under certain conditions.
Geography & Man-Made Objects
Looking beyond the biological world, certain geography and man-made creations appear green for various physical, chemical, and psychological reasons. Some examples include:
|Green minerals||Emeralds, jade, malachite, serpentine|
|Copper patina||Oxidized copper takes on a green “patina”|
|Green traffic lights||Go/proceed signal|
|Green ink||Pigmented ink absorbing blue/yellow light|
|The Green Monster||Iconic green wall at Fenway Park baseball stadium|
The specific causes vary – malachite contains copper that absorbs certain light, patina is oxidized copper reacting to air, and green lights and inks are psychological associations. But the net result is the same green color throughout our physical world.
In summary, green coloration arises in diverse living organisms and objects through various chemical, biological, and psychological mechanisms. But the ubiquity of green throughout so much of nature points to its crucial role in processes like photosynthesis and as an evolutionary adaption for camouflage and signaling. Next time you notice something green, consider how that color came to be and what advantages it may confer. Green truly is one of the most pervasive hues across biology, geography, and everyday life.