Coffea L.
Coffea arabica
Coffea canephora
Coffea liberica
For most coffee drinkers 'coffee' signifies either Arabica (right) or Robusta (in the middle), two species selected from more than one hundred Coffea species by Homo sapiens. A further species sporadically mentioned is Liberica (left), which is despite its large fruits and seeds (beans) economically and organoleptically insignifcant.
Interestingly, Arabica evolved in East Africa 'very recently', that is between 600 and 20 kA BP, possibly as a hybrid between Robusta and C. eugenioides. The latter has a low (about 0.5 % d. wt) caffeine content. In essence, even though we may prefer the label "pure Arabica", we owe most of the stimulating power in it (ca 1.2 %) to the Robusta ancestor met up with that 'softy'.
Although European travellers and naturalists got in contact with Arabica coffee by the end of the 16th century (Rauwolf, Clusius, Alpino), their descriptions or illustrations do not provide helpful information for the diagnosis of the plant species and about its use. Similarly, botanists and apothecaries of the 17th century have contented themselves with copying the above-mentioned authorities (Sprecher von Bernegg 1934).
the caffeine plants
