With five previous years of Advent Botany I was surprised that none of us have so far covered coffee. OK, it’s not a Christmassy spice, or a festive decoration, but by this time in the year I’m sure I’m not the only one feeling more than my usual need for this botanical pick-me-up. As we approach the shortest day of the year a good cup (or several) of coffee is pretty much all that’s keeping me from attempting to hibernate.
Not only that, but as this snippet from the magazine ‘The Hospital’ from January 1889 suggests, there is also coffee’s reputation for counteracting the effects of alcohol. Although, rather than allowing people to deal with the morning after the night before, this article also seems to suggest that if people can get their hands on good coffee, then they won’t bother drinking the alcohol in the first place.
Caffeine is found in several other plants such as tea and kola, but it is coffee that has earnt the reputation as the go-to drink for keeping us alert. In nature, caffeine has a protective function, deterring insect grazing through its bitter taste and toxic properties. It is found in all parts of the coffee plant, including the leaves, and in high concentrations in very young seedlings, but of course it is the roasted beans that we prepare for the drink. Coffee ‘beans’ are seeds which come in pairs in small fruits which turn red as they ripen. Known as cherries, the fruits are described botanically as called drupes. These are thin skinned fleshy berries with a hardcoated seed inside (much like an actual cherry, olives or dates) but coffee is a little uncommon for having two seeds rather than the more usual single seed.
Coffee is in the Rubiaceae, a diverse family including herbaceous plants such as the dye plant madder (Rubia tinctorial) and the quinine-producing Cinchona trees used for flavouring tonic water. The genus Coffea contains over 120 species of shrubs and small trees with opposite pairs of glossy dark green leaves and jasmine-scented flowers. Despite this, there are few species which are used commercially. Coffea arabica and C. canephora account for almost all the world’s coffee production with C. liberica coming a very distant third.
C. arabica originates in Ethiopia and was the first coffee to be cultivated. Now it is considered the gold-standard of coffee, less bitter and less acidic than other species. It is the most widely grown, accounting for the majority of worldwide coffee production and Brazil is the biggest single exporter. However, C. canephora (known as robusta) is easier to grow and higher yielding. Vietnam is the world’s largest producer of robusta, after the French smuggled the plant in to the country in the 19th century. The beans contain twice as much caffeine as arabica and produce a more bitter, earthier-tasting coffee. Robusta is particularly used for the production of instant coffees, and is also added into coffee blends (such as Italian expresso) as it is said to produce a better crema on top.
Well, looking out all these objects from the herbarium has given me a bit of a thirst, so I think it’s probably high time I stopped for a coffee break and sampled the blends at our new Museum cafe (perhaps with a little mince pie on the side). Anyone ready to join me?