Robusta coffee is from the hardier Coffea canephora specie and is a robust shrub or small tree that grows up to 30 feet in height, but with a shallow root system.  Robusta is much more resistant to the devastating coffee leaf rust and many other diseases prone to attack coffee shrubs.  The Robusta coffee specie was first collected in 1890 from the Lomami River, a tributary of the Congo River, and was conveyed from Zaire to Brussels and ended up in Java around 1900. From Java, further breeding resulted in the establishment of Robusta plantations in many countries.

Robusta is grown at lower elevations that push the ideal growing conditions from one end of an extreme to another. Grown in hot and humid environments, with excessive year-round rainfall, coffee shrubs produce fruit almost endlessly with no particular season in mind, as the higher temperatures tend to accelerate the coffee berries ripen.  Under these conditions, much of the fruit tends to rot or be eaten by prey before it has the chance to germinate and give life to the next generation of coffee trees. The Robusta coffee fruits are rounded and take up to 11 months to mature; the seeds are oval in shape and smaller than those of Arabica typically.

The coffee tree’s biological response is to produce an excessive quantity of fruit to overwhelm the adverse conditions, so that a few of the seeds might succeed in becoming the future generation. As a result, lowland coffees mostly lack substance, and the coffee flavor is often harsh, bitter, and dirty, as well as anywhere between 40%–100% more caffeine than Arabica, and quite undesirable overall. Yet, the tendency of these lowland coffees to be low cost and easy to grow makes them ideal for commercial mass production.  For this reason, it is used as an inexpensive substitute for Arabica in many commercial low quality coffee blends.

Good quality Robusta beans can be found and are quite rare and mostly are used in traditional Italian style espresso blends to provide a full-bodied taste, neutral base and a better Crèma.  Robusta coffee is grown in West and Central Africa, throughout South-East Asia and to some extent in Brazil, where it is known as Conillon.