Coffea canephora, known as Robusta, is native to western and central sub Saharan Africa from Liberia to Tanzania and south to Angola. In the wild it grows into a tree of about 10 meters on a shallow root mat, and its berries take 10 to 11 months to ripen. It survives through chemistry: about 2.7% caffeine against Arabica’s roughly 1.5%, enough to act as a nerve agent on insects, plus antimicrobial polyphenols. Those same defenses, along with lower sugar, low acidity, and pyrazines that read as woody or rubbery, give it the harsh taste that landed it in instant coffee and cheap blends.

Italian espresso roasters blend Robusta in on purpose. Its lower lipid content, up to 60% less fat than Arabica, and its polysaccharides build a thicker, longer lasting crema. In 1927 on Timor a natural cross with Arabica produced the Timor hybrid, which carried resistance to coffee leaf rust into Arabica breeding. Today Vietnam, where French colonists introduced Robusta in the late 19th century, exports over 40% of the world supply, and canephora makes up roughly 45 to 46% of all coffee production.

• Brazil grows a third of the world’s coffee but ranks second in Robusta at 25%, followed by Indonesia at 13% and India and Uganda at 5%.
• Linnaeus classified Arabica in 1753, but Robusta was not classified until 1897.
• Leaf rust, Hemileia vastatrix, strips leaves with orange lesions until the plant starves.
• The species has naturalized in Borneo, French Polynesia, Costa Rica, Nicaragua, and the Caribbean.
• Under drought or heat it can thicken its leaves and change its stomata density, an example of phenotypic plasticity.