The Coffea plant, a shrub that is endemic to tropical areas of Africa, mainly Ethiopia and Sudan, produces coffee beans as its seeds. Various Coffee Beans: Arabica and Robusta coffee beans are the two most common varieties. Arabica beans are regarded as being of higher grade and have a milder flavor with less caffeine. Robusta beans are more resilient, taste stronger and more bitter, and have more caffeine in them. Other, less popular types include Liberica and Excelsa.