Coffee comes from the Latin form of the genus Coffea, a member of the Rubiaceae family which includes more than 500 genera and 6,000 species of tropical trees and shrubs. Other members of the family include the gardenias and plants which yield quinine and other useful substances, but Coffea is by far the most important member of the family economically.

Eighteenth century Swedish botanist Carolus Linnaeus (1707-1778) first described the genus but, to this day, botanists still disagree on the classification because of the wide variations that occur in coffee plants and seeds. Linnaeus classified the coffee shrubs in the family Rubiaceae comprising 4,500 species of which 60 are called 'coffea'. Species of coffea range from small shrubs to trees as tall as 32 feet high and the leaves can range in colour from purple to yellow, however, green is the predominant colour.

Coffee is a tropical plant which grows between the Tropic of Cancer and the Tropic of Capricorn but requires very specific environmental conditions for commercial cultivation. Temperature, rainfall, sunlight, wind and soils are all important, but requirements vary according to the varieties grown. All coffee neesd good drainage, but it can grow on soils of different depths, pH and mineral content, given suitable applications of fertilizer.

Frost is the worst climatic event that could affect a coffee plantation. Though an unusual occurrence (approximately once every 20 years at latitudes above 20 degrees), one night below 0 degrees celcius is enough to cause extensive defoliation with little hope of later plant recovery. Plantation altitude and local wind and rainfall conditions may affect this phenomenon - the highest danger from frost being in southern Brazil or, closer to the Equator, at altitudes around 2,000 metres.

Cultivation of coffee trees begins with planting the seeds in potting soil and tended in nurseries for 9 to 18 months, until they reach a height of 18 to 24 inches when they are transplanted to permanent groves. Once planted, the bean, enclosed in its endocarp, develops rootlets in the earth and rises up at the top of a fragile stem. When the bean falls, two round "cotyledon" leaves appear, forming the shoot. It takes a year for the plant to reach just 30 centimetres tall.

After three to four years, when they reach maturity, coffee plants bear fruit in lines or clusters along their branches. The fruit turns red and cherry-like when it is ready to be harvested. Depending on the type of coffee plant, the cherry takes between 6 to 11 months to ripen.

The traditional way to grow coffee trees is to grow compatible trees nearby, to keep the coffee trees and their developing fruit from the sun. Often these are economic crops as well such as bananas which mimic the natural habitat of coffee. The modern techniques are to use irrigation systems and fertilizers. Coffee is grown on both large estates and in the smallest of forest clearings.

Manpower availability affects the planting style determining plant density. Also field operations like pruning and weed control are implemented in different ways according to local labour situations. Pruning is seldom implemented due to the high labour requirement - just when shrubs tend to grow too tall to be harvested without the aid of a ladder are the higher branches cut to keep the plant no taller than around 2 metres.

  • Nematodes invasion of the roots (eg Meloidogyne coffeicola)
  • Insect attack of the leaf (Leucoptera coffeella = bicho mineiro)
  • Insect attack of the cherry (Hypothenemus hampeii = coffee borer)
  • Fungal disease of the seed (eg Colletotrichum coffeanum = coffee berry disease)

Pest control is important to improve yield and product quality, and often even to assure the very plantation's survival.

Artificial addition of manure or chemical fertilizers is seldom used in coffee farms. Sometimes just cut weeds and coffee cherry pulp deriving from crop processing are spread between rows. Of course soil depletion follows if many years of coffee growing are not alternated with different crops.

There are about 25 major species within Coffea, but the typical coffee drinking is likely to be familiar with just two: Coffea arabica and Coffea canephora (var. robusta). Arabica is autogamous, that is to say, capable of fertilising itself, whereas Robusta is allogamous.

Coffea Arabica:
Arabica represents approximately 70 percent of the world's coffee production. Typica and Bourbon are the two best known varieties of C. arabica, but many strains have been developed, including Caturra (from Brazil and Colombia), Mundo Novo (Brazil), Tico (Central America), the dwarf San Ramon and Jamaican Blue Mountan.

Coffea arabica is a spontaneous mutation of pre-existing races which doubled the number of chromosomes in the cell. As a result it has 44 chromosomes compared with 22 for most other coffee varieties.

The arabica plant is an evergreen, typically large bush with dark green, oval shaped leaves that can reach a height of 14 to 20 feet fully grown. On plantations the plants are kept at a height of about two to three metres to facilitate harvesting and nourish heavy bearing of berries

After planting, arabica trees mature in three to four years, when they produce their first crop. The arabica plant can continue to produce fruits for about 50 years although the fruit yield decreases significantly after about 30. Arabica trees prefer a seasonal climate of 60-75 degrees Fahrenheit and an annual rainful of 60 inches.

Primary, non-renewable branches grow from the trunk at an average distance of 15 cm. The plants have taproots that are not very deep. The bright green leaves are shiny on top and dull on the underside; they vary from 5 to 20 cm in length and come to a point. Its' branches carry bouquets of 5-12 small, white flowers with a jasmine-like fragrance that spreads throughout the plantations.

The five-petal flowers fade quickly as they wilt as soon as fertilisation has taken place. They are quickly replaced by others, however. Once fertilised they give way to the coffee cherry; these are oval-shaped berries with, usually, two beans side-by-side with their flat sides together. When only one bean develops from a cherry it is called a peaberry. Each tree can produce between 1 and 12 pounds of coffee a year, depending on soil, climate and many other factors. At high altitudes the plants generally blossom once, while in the lower-lying areas where there are no great seasonal changes the plants blossom several times a year - so that there are almost always fruits on the plants.

A hybrid of arabica, Maragogype - called the elephant bean because of its large size - originated from the Maragogype County in the Bahia state of Brazil. Today it is grown in Guatemala, Mexico, Nicaragua, Honduras, El Salvador, Brazil and Zaire.

Coffee canephora (var. Robusta):
Coffea canephora provides the robusta beans. Robusta, which can grow up to 32 feet in height as a shrub or tree, has a shallow root system. The fruits are round and take nearly a year to mature. The seeds are rounder and smaller than arabica beans. Robusta coffee was discovered in the Congo in 1898 and has become widespread since then - representing about 1/4 of the world's coffee production. It is grown in West and Central Africa, throughout Southeast Asia, and parts of South America including Brazil, where it is known as Conilon.

Robusta trees produce their first crop 3 to 4 years after planting and they remain fruitful for 20 to 30 years. The trees prefer equatorial conditions with tempratures between 75 and 85 degrees Fahrenheit and an annual rainfall of 60 inches.

Robusta tends to be a hardier, more disease-resistant bean than Arabica which is less expensive to maintain and produces a higher yield. Consequently Robustas are used for the less expensive canned and instant coffees.

Arabica coffee grows best at high altitudes (from 1500m to 2500m) while Robusta coffee prospers in lowlands such as rainforests. Before roasting, the colour of robusta beans are yellow to light brown in appearance whereas arabica are green with silver/blueish shades.

Some differences between Arabica and Robusta:

  Arabica Robusta
Date Described 1753 1895
Chromosomes 44 22
Time from flower to ripe cherry 9 months 10-11 months
Flowering after rain irregular
Ripe cherries fall stay
Yield (kg beans/ha) 1500-3000 2300-4000
Root system deep shallow
Optimum temperature (yearly avg) 15-34 deg C 24-30 deg C
Optimal rainfall 1500-2000mm 2000-3000mm
Optimum growth height 1000-2000m 0-700m
Caffeine content of beans avg 1.2% avg 2.0%
Shape of beans flat oval