Can scientists save your morning cup of coffee?

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Coffea stenophylla that he found growing wild in Sierra Leone. A cup brewed from the plant’s berries, he wrote, was even better than one brewed from Arabica. Intrigued, Dr Davis went searching.

He and his colleagues found the species still growing in Sierra Leone. They also managed to track down another lost coffee species. Known as Coffea affinis, it too was noted (this time in 1925) for its pleasant flavour.

Both species come from Sierra Leone’s hot and seasonally dry lowland hills, hinting that they can probably cope with warmer climes than either Arabica or Robusta. It was fortunate that Dr Davis found the plants when he did, for habitat loss means both are threatened with extinction. In 2021 Dr Davis published a paper revealing that, compared with Brazilian Arabica, C.

stenophylla was fruitier, had a better acidity and a more complex flavour profile—though slightly fewer of these characteristics than Ethiopian Arabica. In a blind taste test, judges given C. stenophylla thought they were drinking Arabica 81% of the time.

Dr Davis says that C. affinis has demonstrated similar flavours. Heat tolerance and a nice taste are not the only important traits.

Coffea dewevrei, known as Excelsa, is easy to grow, high-yielding and has a good flavour. Its biggest advantage might be its resistance to the coffee-rust fungus. It was discovered in 1902, in what is now the Democratic Republic of Congo.

C. dewevrei quickly became the dominant coffee crop in parts of central Africa. But in 1933 disaster struck.

A new disease called coffee wilt emerged, devastating crops and leaving farmers destitute. They gave up on Excelsa and focused on Arabica and Robusta instead. Now, with climate change making rust a more serious issue, researchers