There are a wide range of coffee species, but the two most commonly available are Arabica and Robusta.
Arabica has milder but more complex taste characteristics. It grows better at higher altitudes and requires intense cultivation. Arabica is predominantly grown in the tropical and equatorial strips of America, Africa and Asia.
Robusta has a simpler taste profile, with a bitter, astringent flavour. It costs much less to grow, as it is more resistant to tropical heat and parasites and thrives at lower altitudes. This, combined with the fact that it is more soluble than Arabica beans, means that it is commonly used as the major ingredient in 'instant' coffees.
Arabica and Robusta are genetically quite distinct: the first has 44 chromosomes, the second only 22.
The caffeine content of Arabica is about 1%. Robusta ranges from 2 to 4.5%.
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