Coffee originates from the seed of a flowering plant, classified botanically as a woody shrub or small tree. This perennial evergreen produces a fruit, commonly called the coffee cherry. The beans used for brewing are the seeds found inside this fruit. Cultivation requires specific tropical conditions, transforming the small seed into one of the world’s most traded commodities.
The Botanical Identity of the Coffee Plant
The source of the world’s coffee belongs to the genus Coffea, a member of the family Rubiaceae. Although the plant can naturally reach heights of up to 10 meters, farmers typically prune it to a manageable two to five meters for easier harvesting. It is a woody perennial evergreen, retaining its dark-green leaves and producing fruit over many years.
The two species dominating global production are Coffea arabica (Arabica) and Coffea canephora (Robusta). Arabica accounts for the majority of the world’s coffee and is prized for its aromatic and complex flavor. Robusta is a hardier plant, containing nearly double the caffeine content of Arabica. It typically produces a stronger, more bitter flavor, making it a common choice for espresso blends and instant coffee.
The Journey From Cherry to Coffee Bean
The commercially used “coffee bean” is botanically the seed of the coffee plant’s fruit, a fleshy drupe known as the coffee cherry. This fruit has a layered structure that must be meticulously removed to isolate the seed. The outermost layer is the exocarp (skin), followed by the mesocarp (a sweet layer of pulp).
Beneath the pulp is a sticky, sugary material called mucilage, which encases the parchment—a thin, protective shell that covers the seed. Inside the parchment typically lie two seeds, or beans, nestled face-to-face, each covered by a fine layer of silverskin. The final green bean is revealed only after the surrounding layers of fruit are removed through various processing methods.
Processing is the initial step after harvest and can be broadly categorized into wet (washed) and dry (natural) methods. The dry method involves letting the entire cherry dry in the sun, allowing the fruit pulp to ferment and impart flavor to the seed before the outer layers are mechanically removed. Conversely, the wet method immediately removes the skin and pulp, then uses fermentation in water to break down the mucilage before the bean is dried. A third approach, the pulped natural or honey process, removes the skin but leaves some of the mucilage intact during the drying phase, offering a middle ground in flavor complexity.
Ideal Growing Conditions
The cultivation of the coffee tree is limited to a specific geographic region known as the “Coffee Belt,” which encircles the globe between the Tropics of Cancer and Capricorn. This tropical and equatorial band provides the stable, warm climate and consistent rainfall necessary for the plant’s delicate growth cycle. Coffee plants require significant annual rainfall, with a distinct dry period needed to encourage flowering.
Temperature is a primary factor, with Arabica preferring a cooler range of approximately 15°C to 24°C, which is often found at higher altitudes, generally between 1,200 and 2,200 meters above sea level. Robusta plants are more tolerant of heat, thriving in temperatures between 24°C and 30°C and at lower elevations, up to about 800 meters. Frost is highly damaging to all coffee plants, making regions prone to freezing unsuitable for commercial production. The plants grow best in rich, well-drained soil, often volcanic in origin, that provides the necessary nutrients for producing high-quality cherries.