Robusta

Where it comes from

Coffea canephora is native to a broad belt of lowland tropical Africa, from West Africa across the Congo basin to Uganda. It was brought into large-scale cultivation only at the end of the nineteenth century, after coffee leaf rust had destroyed arabica plantations across Asia: planters needed a coffee that would survive, and this one did. "Robusta" was originally the name of one cultivated form and has become the trade name for the whole species. In Brazil the species is grown as Conilon, a distinct group within it.

How it grows

Robusta tolerates heat and humidity that arabica cannot, grows at low altitude, yields more, and resists leaf rust far better. Unlike arabica it cannot pollinate itself, so plants grown from seed vary and commercial plantings are usually clones raised from cuttings. Its need for water varies with its ancestry: plants of the West African group are described as drought resistant and those of the Central African group as susceptible, and in Vietnam and Brazil much of the crop is irrigated. Its higher caffeine content is thought to be part of its defence against pests.

What it tends to taste like

Robusta is typically heavier in body and more bitter than arabica, with less acidity and with earthy, woody, nutty or dark-chocolate notes. Brewed as espresso it produces a thick, persistent crema.

What it is used for

Most instant coffee, a large share of supermarket and espresso blends — traditional Italian blends in particular use it for body and crema — and the strong, dark coffee of Vietnam, Indonesia and much of West Africa. A small but growing amount is sold as single-origin speciality coffee.

Caffeine content

Generally contains more caffeine than arabica weight for weight: roughly one and a half times as much on average in the one study CoffeeHQ has read that measured many green coffees of both, with overlap between individual coffees.

For what ends up in a cup, the caffeine estimator gives a range by brewing method and dose.

Varieties of robusta

A variety is a distinct, named type within a species — the level at which most of the differences between coffees are bred and selected.

• Robusta and conilon cultivars

Names and classification

The botanical name is Coffea canephora; "Coffea robusta" is an old synonym still seen in the trade. Conilon and robusta are groups within the one species, not separate species. Studies of its wild diversity distinguish a Guinean group from West Africa and a Congolese group from Central Africa, which differ in stature, bean size, ripening and resistance to drought and rust; conilon is presumed to descend from a cross between the two.

Compare

• Arabica

Full side-by-side comparison

• Arabica vs. robusta

Learn it as a course

The Coffee Expert lesson Species and varieties covers this ground in order, with exercises you can do at home.