From Bean to Cup Part 1: The Botany of Coffee

What is coffee?

Coffee branch and cross-section a coffee cherry

Coffee is more than just a bitter, black beverage. Coffee is yes, a drink, but it is also a seed, a fruit, and a genus of plants that grows in specific parts of the world. 

Even though we call coffee a “bean,” it’s not really a bean in the proper sense. A coffee “bean” is actually the seed of a stone fruit called a coffee “cherry”. These cherries mature from five-petaled, white flowers that smell like jasmine, and when the cherries are mature, they can vary in color from different shades of red to orange, yellow, and even purple. The anatomy of a mature coffee cherry in order from outermost to innermost goes like this: skin, pulp, parchment, mucilage, silverskin, and bean. How and when these various outer parts are separated from the bean by the coffee farmer or coffee mill is referred as processing. 

Coffee cherries on a coffee plant branch

Coffee cherries grow on coffee “trees,” which are usually closer to the size of bushes, though some can grow as tall as eight meters in height. According to the SCA, there are about 100 species of coffee! Only a small handful, however, are used in commercial production. Among these are coffea arabica, or Arabica coffee, a self-pollinating plant which accounts for 70% of the world’s coffee production, and coffea canephora, or Robusta coffee, which accounts for the remaining 30%. Other, more rare species of coffee that are not commercially produced include coffee liberica, which produces huge, irregularly shaped beans, coffea stenophylla, which botanists look to for the future of coffee’s survival in light of climate change, coffea eugenioides, which has made a hit on stage at World Coffee Competitions, and Charrier coffee, which produces beans that are caffeine-free! A species can also have many different varieties, like Typica, Bourbon, or the prized Geisha/Gesha - all of which thrive at different elevations, in different environments, and taste different. A variety’s genetic makeup can also make it more or less susceptible to pests or disease and more or less affected by droughts. In order to cultivate more climate-hardy and better-tasting coffee, botanists can cross- breed different varietals and species to create hybrids. The famous SL28 varietal, for example, is a Kenya-grown drought-resistant hybrid created in Scott Labs, and Ruiru 11 is a hybrid resistant to the coffee cherry/berry disease (CBD) common to coffee plants. With climate change and shifting environmental patterns, the practice of creating hybrid plants that can survive changing conditions is increasingly important in the coffee industry.

References:

2011 The Integrated Taxonomic Information System (ITIS) report https://sca.coffee/research/botany - says there are “about 100 species of coffee” https://academic.oup.com/botlinnean/article/158/1/67/2418384 https://varieties.worldcoffeeresearch.org/varieties/sl28 https://varieties.worldcoffeeresearch.org/varieties/catimor-129 https://varieties.worldcoffeeresearch.org/varieties/ruiru-11