The word green is closely related to the Old English verb growan, “to grow”. It is used to describe plants or the ocean. Sometimes it can also describe someone who is inexperienced, jealous, or sick. In America, green is a slang term for money, among other things. Several colloquialisms have derived from these meanings, such as “green around the gills”, a phrase used to describe a person who looks ill.
Several minerals have a green color, including the emerald, which is colored green by its chromium content. Animals such as frogs, lizards, and other reptiles and amphibians, fish, insects, and birds, appear green because of a mixture of layers of blue and green coloring on their skin. By far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize. Many creatures have adapted to their green environments by taking on a green hue themselves as camouflage.
Culturally, green has broad and sometimes contradictory meanings. In some cultures, green symbolizes hope and growth, while in others, it is associated with death, sickness, envy or the devil. The most common associations, however, are found in its ties to nature. For example, Islam venerates the color, as it expects paradise to be full of lush greenery. Green is also associated with regeneration, fertility and rebirth for its connections to nature. Recent political groups have taken on the color as symbol of environmental protection and social justice, and consider themselves part of the Green movement, some naming themselves Green parties. This has led to similar campaigns in advertising, as companies have sold green, or environmentally friendly, products.
The word green comes from the Old English word grene, or, in its older form, groeni. This adjective is closely related to the Old English verb growan (“to grow’) and goes back into Western Germanic and Scandinavian languages. The word designates the color on the visible light spectrum situated between blue and yellow. It is often used to describe foliage and the sea, and has become a symbol of environmentalism. It also is combined with other color names to increase specificity, as in “blue-green”, or with objects, as in “emerald green”. Green is also used to describe jealousy and envy, as well as anyone young, inexperienced, or gullible (probably by analogy to unripe, i.e. unready or immature, fruit). Green is sometimes associated with nausea and sickness. Lastly, green can communicate safety to proceed, as in traffic lights. Overall, greens, along with blues and purples, are frequently described as “cool” colors, in contrast to red and yellow. Some languages have no word separating green from blue (see blue-green across cultures).
The word green is found in several colloquial phrases derived from these meanings: in golf, the region of grass around the hole is trimmed short and referred to as the putting green, or simply, the green. Someone who works well with plants is said to have a green thumb or green fingers, a physically-ill person is said to look green around the gills, and the word greenhorn refers to an inexperienced person. A company is greenwashing if they advertise positive environmental practices to cover up environmental destruction. Green with envy highlights another emotional association, which William Shakespeare had first described as the "green-eyed monster" in Othello and The Merchant of Venice.
In areas that use the U.S. Dollar as currency, green carries a connotation of money, wealth, and capitalism, because green is the color of United States banknotes, giving rise to the slang term greenback for cash. One of the more notable uses of this meaning is found in The Wonderful Wizard of Oz. In this story is the Emerald City, where everyone wears tinted glasses which make everything look green. According to the populist interpretation of the story, the city’s color is used by the author, L. Frank Baum, to illustrate the financial system of America in his day, as he lived in a time when America was debating the use of paper money versus gold.
Human eyes have color receptors known as cone cells, of which there are three types. In some cases, one is missing or faulty, which can cause color blindness, including the common inability to distinguish red and yellow from green, known as deuteranopia or red–green color blindness. Green is restful to the eye. Studies show that a green environment can reduce fatigue.
The perception of green is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nm. The sensitivity of the dark-adapted human eye is greatest at about 507 nm, a blue-green color, while the light-adapted eye is most sensitive about 555 nm, a slightly yellowish green; these are the peak locations of the rod and cone (scotopic and photopic, respectively) luminosity functions.
Green is considered one of the additive primary colors, along with red and blue. Additive combination of primary colors can produce most colors. In subtractive color mixtures, green is created by mixing yellow and blue pigments or dyes. On the HSV color wheel, the complement of green is magenta; that is, a color corresponding to an equal mixture of red and blue light (one of the purples). On a traditional color wheel, based on subtractive color, the complementary color to green is considered to be red.
Many minerals provide pigments which have been used in green paints and dyes over the centuries. Pigments, in this case, are minerals which reflect the color green, rather that emitting it through luminescent or phosphorescent qualities. The large number of green pigments makes it impossible to mention them all. Among the more famous green minerals, however is the emerald, which is colored green by trace amounts of chromium and sometimes vanadium. Chromium(III) oxide (Cr2O3), is called chrome green, also called viridian or institutional green when used as a pigment. For many years, the source of amazonite's color was a mystery. Naturally, many people assumed the color was due to copper because copper compounds often have blue and green colors. More recent studies suggest that the blue-green color results from small quantities of lead and water in the feldspar. Copper is also the source of the green color in malachite pigments, chemically known as basic copper(II) carbonate. Early painters would also use copper in the form of verdigris mixed with wax and turpentine to create green pigmentation in paints. Mixtures of oxidized cobalt and zinc were also used to create green paints as early as the 18th century. A more complete list of green minerals and pigments can be seen here
There is no natural source for green food colorings which has been approved by the US Food and Drug Administration. Chlorophyll, the E numbers E140 and E141, is the most common green chemical found in nature, and only allowed in certain medicines and cosmetic materials. Quinoline Yellow (E104) is a commonly used coloring in the United Kingdom but is banned in Australia, Japan, Norway and the United States. Green S (E142) is prohibited in many countries, for it is known to cause hyperactivity, asthma, urticaria, and insomnia.
To create green sparks, fireworks use barium salts, such as barium chlorate, barium nitrate crystals, or barium chloride, also used for green fireplace logs. Copper salts typically burn blue, but cupric chloride (also known as "campfire blue") can also produce green flames. Green pyrotechnic flares can use a mix ratio 75:25 of boron and potassium nitrate. Smoke can be turned green by a mixture: solvent yellow 33, solvent green 3, lactose, magnesium carbonate plus sodium carbonate added to potassium chlorate.
Green is common in nature, especially in plants. Many plants are green mainly because of a complex chemical known as chlorophyll which is involved in photosynthesis. Some animals are green: these include some frogs, toads, some turtles, some lizards and amphibians, some snakes, some birds such as parrots, caterpillars and some insects such as praying mantis. Green algae and green plankton are important food sources at the bottom of the food chain. Most fish, reptiles, amphibians, and birds appear green because of a reflection of blue light coming through an over-layer of yellow pigment. Perception of color can also be effected by the environment surrounding. For example, broadleaf forests typically have a yellow-green light about them as the trees filter the light. Turacoverdin is one chemical which can cause a green hue in birds, especially. Invertebrates, such as insects or mollusks, often display green colors because of Porphyrin pigments, sometimes caused by diet. This can causes their feces to look green as well. Other chemicals which generally contribute to greenness among organisms are flavins (lychochromes) and hemanovadin. Animals typically use the color green as camouflage, blending in with the chlorophyll green of the surrounding environment. Humans have imitated this by wearing green clothing as a camouflage in military and other fields. Substances that may impart a greenish hue to one's skin include biliverdin, the green pigment in bile, and ceruloplasmin, a protein that carries copper ions in chelation.
In many folklores and literatures, green has traditionally been used to symbolize nature and its embodied attributes, namely those of life, fertility, and rebirth. Green was symbolic of resurrection and immortality in Ancient Egypt; the god Osiris was depicted as green-skinned. Stories of the medieval period further portray it as representing love and the base, natural desires of man. Green is also known to have signified witchcraft, devilry and evil for its association with faeries and spirits of early English folklore. It also had an association with decay and toxicity. Actor Bela Lugosi wore green-hued makeup for the role of Dracula in the 1927-28 Broadway stage production. The color, when combined with gold, is seen as representing the fading away of youth. In the Celtic tradition, green was avoided in clothing for its superstitious association with misfortune and death. Green is thought to be an unlucky color in British and British-derived cultures, where green cars, wedding dresses, and theater costumes are all the objects of superstition. In high schools in the United States during the 1960s, it was widely believed that if someone wore green on Thursdays, it meant that they were homosexual. Spider-Man villains were often colored green to represent a contrast to the hero's red.
Green has become the symbolic color of environmentalism, chosen for its association with nature, health, and growth. The Green Party is any of various political parties emphasizing ecology, grassroots democracy, nonviolence, and social justice. Green Parties, now active in over one hundred countries, are more broadly included in the green movement, and most are members of the Global Green Network.
The association of green with advocates of the environment has extended to other circles as well, as is the case with Patriarch Bartholomew I of Constantinople, who is often referred to as the “Green Patriarch” because the new environmental focus which he brought about within the Ecumenical Patriarchate.
Several countries use green on their flags for symbolic or cultural reasons. Green, for example is one of the three colors (along with red and black, or red and gold)) of Pan-Africanism. Several African countries thus use the color on their flags, including South Africa, Ghana, Senegal, Mali, Ethiopia, Togo, Guinea, Benin, and Zimbabwe. The Pan-African colors are borrowed from the Ethiopian flag, one of the oldest independent African countries. Green in these cases represents the natural richness of Africa.
Many flags of the Islamic world are green, as the color is considered sacred in Islam. The flag of Libya consists of a simple green field with no other characteristics. It is the only national flag in the world with just one color and no design, insignia, or other details.
Other countries use flags for reasons of heraldry, or to represent lush national vegetation. In heraldry, green is called vert (French for "green"). Fourteenth century documents describe vert as a symbol of "jolliness and youth, but also of beauty and shame" as well as of death. Vert is used for the flags of Wales and Hungary, and is the basis for the Brazilian flag as well. Other countries using green in their flags use it to represent their country's lush vegetation, as in the flag of Jamaica, and hope in the future, as in the flag of Nigeria.
Green is one of the bottom of the three bands on the Flag of India. The green stands for fertility and prosperity, though initially before it came into being, it stood for Islam, the second-most predominant religion in India.
Green is a symbol of Ireland, which is often referred to as the “Emerald Isle”. The color is particularly identified with the republican and nationalist traditions in modern times. It is used this way on the flag of the Republic of Ireland, in balance with white and the Protestant orange. Green is a strong trend in the Irish holiday St. Patrick’s Day.
Green is considered the traditional color of Islam, likewise because of its association with nature. This is for several reasons. First, Muhammad is reliably quoted in a hadith as saying that “water, greenery, and a beautiful face” were three universally good things. In the Qur'an, sura Al-Insan, believers in God in Paradise wear fine green silk. Also, Al-Khidr (“The Green One”), is a Qur’anic figure who met and traveled with Moses. The flag of Hamas, as well as the flag of Iran, is green, symbolizing their Islamist ideology.
In the metaphysics of the "New Age Prophetess", Alice Bailey, in her system called the Seven Rays which classifies humans into seven different metaphysical psychological types, the "third ray" of "creative intelligence" is represented by the color green. People who have this metaphysical psychological type are said to be "on the Green Ray". In Hinduism, Green is used to symbolically represent the fourth, heart chakra (Anahata). Psychics who claim to be able to observe the aura with their third eye report that someone with a green aura is typically someone who is in an occupation related to health, such as a physician or nurse, as well as people who are lovers of nature and the outdoors.
Also, Roman Catholic and more traditional Protestant clergy wear green vestments at liturgical celebrations during Ordinary Time. In the Eastern Catholic Church, green is the color of Pentecost. Green is one of the Christmas colors as well, possibly dating back to pre-Christian times, when evergreens were worshipped for their ability to maintain their color through the winter season. Romans used green holly and evergreen as decorations for their winter solstice celebration called Saturnalia, which eventually evolved into a Christmas celebration.