Coffea | |
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Flowering branches of Coffea arabica | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Gentianales |
Family: | Rubiaceae |
Tribe: | Coffeeae |
Genus: | Coffea L. |
Type species | |
Coffea arabica |
Coffea is a genus of flowering plants in the family Rubiaceae. Coffea species are shrubs or small trees native to tropical and southern Africa and tropical Asia. The seeds of some species, called coffee beans, are used to flavor various beverages and products. The fruits, like the seeds, contain a large amount of caffeine, and have a distinct sweet taste.
The plant ranks as one of the world's most valuable and widely traded commodity crops and is an important export product of several countries, including those in Central and South America, the Caribbean and Africa. The coffee trade relies heavily on two of the over 120 species, Coffea arabica (commonly known simply as "Arabica"), which accounts for 60–80% of the world's coffee production, and Coffea canephora (known as "Robusta"), which accounts for about 20–40%. [1] [2] Both coffee species are vulnerable to shifts, caused by climate change, in their growing zones, which are likely to result in a decline in production in some of the most important growing regions. [3] [4] [5]
There are over 120 species of Coffea, which is grown from seed. The two most popular are Coffea arabica (commonly known simply as "Arabica"), which accounts for 60–80% of the world's coffee production, and Coffea canephora (known as "Robusta"), which accounts for about 20–40%. [1] [2] C. arabica is preferred for its sweeter taste, while C. canephora has a higher caffeine content. C. arabica has its origins in the highlands of Ethiopia and the Boma Plateau of Sudan, and came about as the result of a hybrid between C. canephora and C. eugenioides. [6]
The trees produce edible red or purple fruits, which are described either as epigynous berries or as indehiscent drupes. [7] The fruit is often referred to as a "coffee cherry", and it contains two seeds, called "coffee beans". [8] Despite these terms, coffee is neither a true cherry (the fruit of certain species in the genus Prunus ) nor a true bean (seeds from plants in the family Fabaceae ).
In about 5–10% of any crop of coffee fruits, only a single bean is found. Called a peaberry, it is smaller and rounder than a normal coffee bean.
When grown in the tropics, coffee is a vigorous bush or small tree that usually grows to a height of 3–3.5 m (9.8–11.5 ft). Most commonly cultivated coffee species grow best at high elevations, but do not tolerate freezing temperatures. [9]
The tree of Coffea arabica will grow fruits after three to five years, producing for an average of 50 to 60 years, although up to 100 is possible. [10] The white flowers are highly scented. The fruit takes about nine months to ripen.
The caffeine in coffee beans serves as a toxic substance protecting the seeds of the plant, a form of natural plant defense against herbivory. Caffeine simultaneously attracts pollinators, specifically honeybees, by creating an olfactory memory that signals bees to return to the plant's flowers. [11] Not all Coffea species contain caffeine, and the earliest species had little or no caffeine content. Caffeine has evolved independently in multiple lineages of Coffea in Africa, perhaps in response to high pest predation in the humid environments of West-Central Africa. [11] Caffeine has also evolved independently in the more distantly related genera Theobroma (cacao) and Camellia (tea). [12] This suggests that caffeine production is an adaptive trait in coffee and plant evolution. The fruit and leaves also contain caffeine, and can be used to make coffee cherry tea and coffee-leaf tea. The fruit is also used in many brands of soft drink as well as pre-packaged teas. [13] [14] [15] [16]
Several insect pests affect coffee production, including the coffee borer beetle ( Hypothenemus hampei ) and the coffee leafminer ( Leucoptera caffeina ).
Coffee is used as a food plant by the larvae of some Lepidoptera (butterfly and moth) species, Dalcera abrasa, turnip moth and some members of the genus Endoclita , including E. damor and E. malabaricus.
New species of Coffea are still being identified in the 2000s. In 2008 and 2009, researchers from the Royal Botanic Gardens, Kew, named seven from the mountains of northern Madagascar, including C. ambongensis, C. boinensis, C. labatii, C. pterocarpa, C. bissetiae, and C. namorokensis. [17]
In 2008, two new species were discovered in Cameroon: Coffea charrieriana , which is caffeine-free, and Coffea anthonyi . [18] By crossing the new species with other known coffees, two new features might be introduced to cultivated coffee plants: beans without caffeine and self-pollination.
In 2011, Coffea absorbed the twenty species of the former genus Psilanthus due to the morphological and genetic similarities between the two genera. [19] Historically, the two have been considered distinct genera due to differences in the length of the corolla tube and the anther arrangement: Coffea with a short corolla tube and exserted style and anthers; Psilanthus with a long corolla tube and included anthers. However, these characteristics were not present in all species of either respective genus, making the two genera overwhelmingly similar in both morphology and genetic sequence. This transfer expanded Coffea from 104 species to 124, and extended its native distribution to tropical Asia and Australasia.
The coffee genome was published in 2014, with more than 25,000 genes identified. This revealed that coffee plants make caffeine using a different set of genes from those found in tea, cacao and other such plants. [20]
A robust and almost fully resolved phylogeny of the entire genus was published in 2017. [11] In addition to resolving the relationships of Coffea species, this study's results suggest Africa or Asia as the likely ancestral origin of Coffea and point to several independent radiations across Africa, Asia, and the Western Indian Ocean Islands.
In 2020, a technique of DNA fingerprinting, or genetic authentication of plant material, was proven effective for coffee. [21] For the study, scientists used DNA extraction and SSR marker analysis. This technique or similar ones may allow for several improvements to coffee production such as improved information for farmers as to the susceptibility of their coffee plants to pests and disease, a professionalized coffee seed system, and transparency and traceability for buyers of green, un-roasted coffee.
Rubiaceae is a family of flowering plants, commonly known as the coffee, madder, or bedstraw family. It consists of terrestrial trees, shrubs, lianas, or herbs that are recognizable by simple, opposite leaves with interpetiolar stipules and sympetalous actinomorphic flowers. The family contains about 13,500 species in about 620 genera, which makes it the fourth-largest angiosperm family. Rubiaceae has a cosmopolitan distribution; however, the largest species diversity is concentrated in the tropics and subtropics. Economically important genera include Coffea, the source of coffee, Cinchona, the source of the antimalarial alkaloid quinine, ornamental cultivars, and historically some dye plants.
Coffee is a beverage brewed from roasted coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content. It has the highest sales in the world market for hot drinks.
Coffea arabica, also known as the Arabica coffee, is a species of flowering plant in the coffee and madder family Rubiaceae. It is believed to be the first species of coffee to have been cultivated and is the dominant cultivar, representing about 60% of global production. Coffee produced from the less acidic, more bitter, and more highly caffeinated robusta bean makes up most of the remaining coffee production. The natural populations of Coffea arabica are restricted to the forests of South Ethiopia and Yemen.
A coffee bean is a seed from the Coffea plant and the source for coffee. It is the pip inside the red or purple fruit. This fruit is often referred to as a coffee cherry, and like the cherry, it is a fruit with a pip. Even though the coffee beans are not technically beans, they are referred to as such because of their resemblance to true beans. The fruits most commonly contain two stones with their flat sides together. A small percentage of cherries contain a single seed, instead of the usual two, called a "peaberry". The peaberry occurs only between 10% and 15% of the time, and it is a fairly common belief that they have more flavour than normal coffee beans. Like Brazil nuts and white rice, coffee beans consist mostly of endosperm.
Coffea canephora is a species of coffee plant that has its origins in central and western sub-Saharan Africa. It is a species of flowering plant in the family Rubiaceae. Though widely known as Coffea robusta, the plant is scientifically identified as Coffea canephora, which has two main varieties, robusta and nganda.
Tricalysia is a genus of flowering plants in the family Rubiaceae. The genus is found in tropical and southern Africa and on the islands in the Western Indian Ocean.
Coffea liberica, commonly known as the Liberian coffee, is a species of flowering plant in the family Rubiaceae from which coffee is produced. It is native to western and central Africa, and has become naturalised in areas including Colombia, Venezuela, the Philippines, Borneo and Java.
Coffea charrieriana, also known as Charrier coffee, is a species of flowering plant from the Coffea genus. It is a caffeine-free coffee plant endemic to Cameroon in Central Africa. It is the first recorded caffeine-free Coffea in Central Africa, and the second to be recorded in Africa. The first caffeine-free species was previously discovered in Kenya, named C. pseudozanguebariae. The International Institute for Species Exploration at Arizona State University and a committee of taxonomists and scientists voted C. charrieriana as one of the top 10 species described in 2008.
Caffeine synthase is a methyltransferase enzyme involved in the caffeine biosynthesis pathway. It is expressed in tea species, coffee species, and cocoa species. The enzyme catalyses the following reactions:
Coffee is Uganda's top-earning export crop. In 1989 Uganda's coffee production capacity exceeded its quota of 2.3 million bags, but export volumes were still diminished by economic and security problems, and large amounts of coffee beans were still being smuggled out of Uganda for sale in neighbouring countries. Uganda is one of the few countries in the world with indigenous coffee, with Robusta coffee growing wild around Lake Victoria.
3,4-Dimethoxycinnamic acid is a cinnamic acid derivative isolated from coffee beans.
Ixoroideae is a subfamily of flowering plants in the family Rubiaceae and contains about 4000 species in 27 tribes.
Gardenieae is a tribe of flowering plants in the family Rubiaceae and contains about 586 species in 53 genera.
Coffeeae is a tribe of flowering plants in the family Rubiaceae and contains about 333 species in 11 genera. Its representatives are found in tropical and southern Africa, Madagascar, the western Indian Ocean, tropical and subtropical Asia, and Queensland.
Octotropideae is a tribe of flowering plants in the family Rubiaceae and contains about 103 species in 18 genera. Its representatives are found in the paleotropics. The genera previously placed in the tribe Hypobathreae are now placed in Octotropideae.
Coffea kapakata, also known as kapakata, is a putative species of plant in the genus Coffea, more commonly known as coffee, that is native to western Angola and Congo. Specimens were collected in 1932, but precise locality details are uncertain, and no other specimens have since been discovered. Because so little information is known about it, its conservation status is categorised as 'data deficient'.
Coffea stenophylla, also known as highland coffee or Sierra Leone coffee, is a species of Coffea originating from West Africa.
Coffea racemosa, also known as racemosa coffee and Inhambane coffee, is a species of flowering plant in the family Rubiaceae. It has naturally low levels of caffeine, less than half of that found in Coffea arabica, and a quarter of that in Robusta coffee.