Arabica vs. Robusta

All coffee beans come from plants in the genus Coffea. Although there are thousands of species of plants within this genus, with tremendous variance in size and shape, only two are of commercial importance: Coffea arabica, and Coffea canephora, the latter more commonly called robusta, after a prime variety. A third species, Coffea liberica has found some localized production in Liberia, but it is of minor significance in the global market.

Arabica is genetically distinct: it has four sets of chromosomes, whereas robusta, and liberica each have two.

Over sixty-five percent of the coffee grown throughout the world is arabica, but much of it is unexceptional. On its own, the label "arabica" is no assurance of quality: As noted, although Brazil grows some excellent coffee, a sizeable portion of the arabica grown there is of quite poor quality, to the point where the coffee trade uses a particular term, "Rioy" (from Rio de Janeiro), to describe certain particularly harsh, pungent coffees.