The coffee tree is an evergreen shrub, which in the wild can grow up to 30 feet high, but is kept trimmed to 6-9 feet to facilitate harvesting. There are two commercially significant coffee species—Coffeea Arabica and Coffeea Robusta.

Plants produce coffee cherries, which usually contain two coffee seeds shaped like two half beans. Arabica cherries are oblong, while those of Robusta are round.

All high-quality coffee comes from arabica trees. The ideal elevation for arabica growth is between 2000 and 6000 feet above sea level and average temperatures shouldn't be over 75 degrees. The higher the altitude, the slower the growth, which results in greater bean density and flavor. Because of its superior quality and taste, and higher cultivation costs, arabica is more expensive than robusta.

The tougher robusta bean variety yields greater volumes of coffee per growing area, is more resistant to disease and tolerates higher temperatures, making it easier and cheaper to cultivate. This bean grows best in humid, tropical climates at altitudes between sea level and 3200 feet. Robusta beans have less flavor, and a higher caffeine content than arabica beans, and are a key ingredient in commercial coffees.