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Coffea

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This article is about the biology of coffee plants. For the beverage, see Coffee.

Coffea
Flowering branches of Coffea arabica
Scientific classification
Kingdom:
Plantae
(unranked):
Angiosperms
(unranked):
Eudicots
(unranked):
Asterids
Order:
Gentianales
Family:
Rubiaceae
Subfamily:
Ixoroideae
Tribe:
Coffeeae
Genus:
Coffea

Type species
Coffea arabica
Coffea canephora.

Coffea is a genus of flowering plants whose seeds, called coffee beans, are used to make various coffee beverages and products. It is a member of the family Rubiaceae. They are shrubs or small trees native to tropical and southern Africa and tropical Asia. Coffee 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.

Cultivation and use

Coffea cherries, Bali

Several species of Coffea may be grown for the seeds. Coffea arabica accounts for 75-80 percent of the world's coffee production, while Coffea canephora accounts for about 20 percent.[1]

The trees produce edible red or purple fruits called "cherries" that are described either as epigynous berries or as indehiscent drupes.[2] The cherries contain two seeds, the so-called "coffee beans", which—despite their name—are not true beans. In about 5-10% of any crop of coffee cherries, only a single bean, rather than the usual two, is found. This is called a peaberry, which is smaller and rounder than a normal coffee bean. It is often removed from the yield and either sold separately (as in New Guinea peaberry), or discarded.

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.[citation needed]

The tree of Coffea arabica will grow fruits after three to five years, and will produce for about 50 to 60 years (although up to 100 years is possible).[3] The white flowers are highly scented. The fruit takes about 9 months to ripen.

Coffee flower
Coffee cherry cross section
Coffea racemosa fruits

Ecology

The caffeine in coffee "beans" is a natural plant defense against herbivory, i.e., a toxic substance that protects the seeds of the plant. Fruits and leaves are both sources of caffeine as well and a tea can be made of the leaves, but neither are used commercially.

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.

Research

In 2008 and 2009, researchers from the Royal Botanic Gardens, Kew named seven new species of Coffea from the mountains of northern Madagascar, including C. ambongensis, C. boinensis, C. labatii, C. pterocarpa, C. bissetiae, and C. namorokensis.[4]

In 2008, two new species of coffee plants were discovered in Cameroon: Coffea charrieriana, which is caffeine-free, and Coffea anthonyi.[5] 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 2014, the coffee genome was published, 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.[6]

Species

References

  1. ^ Arabica and Robusta Coffee Plant, at the Coffee Research Institute homepage. Retrieved December 2012.
  2. ^ Davis, Aaron P.; Govaerts, Rafael; Bridson, Diane M.; Stoffelen, Piet (2006). "An annotated taxonomic conspectus of the genus Coffea (Rubiaceae)". Botanical Journal of the Linnean Society. 152 (4): 465–512. doi:10.1111/j.1095-8339.2006.00584.x. {{cite journal}}: Unknown parameter |lastauthoramp= ignored (|name-list-style= suggested) (help)
  3. ^ [1]
  4. ^ "Seven species of wild coffee amongst Kew's haul of new discoveries". Royal Botanic Gardens, Kew. 22 December 2009.
  5. ^ Stoffelen, Piet; Noirot, Michel; Couturon, Emmanuel; Anthony, François (2008). "A new caffeine-free coffee from Cameroon". Botanical Journal of the Linnean Society. 158 (1): 67–72. doi:10.1111/j.1095-8339.2008.00845.x.
  6. ^ Callaway, Ewen (4 September 2014). "Coffee got its buzz by a different route than tea". Nature. doi:10.1038/nature.2014.15832. Retrieved 9 September 2014.
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