As a plant, coffee is a member of the Rubaciae species which includes plants like Gardenias. Most coffee varieties, including the second most important variety, Coffea Canephora, have 22 chromosomes and are self sterile, needing bees or other insects and other trees for reproduction. While Canephora itself was only "discovered" (i.e. classified by white guys with degrees) in the Congo in the mid 1890's, it's certain that one of the 60 varieties found in Africa is the progenitor of Arabica. Coffea Arabica, Arabica coffee, has 44 chromosomes and is self pollinating . This means, in the great scheme of things, that it's probably a mutant variety descended from the 22 chromosome types.

What makes this important is that almost all of the 22 chromosome varieties taste like crap. Even the very best have at most a neutral flavour, while the typical taste of roasted Coffea Canephora is usually described as woody or rubbery. Unfortunately, the most prominent type of Coffea Canephora grown, Robusta coffee, has several advantages over Arabica coffees. It will grow well in lowland rainforest areas, it is resistant to many common coffee diseases and insect pests, since it has almost double the caffeine and chlorogenic acid content of Arabica, and it yields about twice as much coffee per tree as Arabica. This has resulted in about 30% of the world's coffee trade being Robusta beans, because they are CHEAP!

Robusta is also used in many espresso blends because it generates heaps of fine, long lasting crema. In my personal opinion this ALWAYS affects the flavour, but some people like the taste. I'm just not one of them. Instant coffees and supermarket blends, where savings of a fraction of a cent can mean megabucks, consume most of the world's Robusta output. An example of a blend containing sufficient Robusta to give it the familiar rubber taste is Lavazza's Crema e Gusto, available worldwide.

Coffea Arabica trees tend to produce at their best in habitats resembling their original environment, in the tropics but at high altitude, with moisture for most of the year but a distinct dry season. Plenty of shade and frequent cloud cover with rich volcanic soils complete the recipe. This doesn't mean that Arabica won't grow outside these parameters, just that the end quality may suffer. In Brazil, for instance, minor climatic variations lead to frosts in the coffee growing areas about once per decade, which can totally destroy a year's crop and even kill many of the trees. You can grow Coffea Arabica as an ornamental plant in your loungeroom in most temperate climates, as long as it gets some sun through the windows. One of the highest priced coffees in the world, Kona coffee from the Big Island (Hawaii) in Hawaii, is grown to within a couple of hundred metres of sea level on recent lava flows. Whether its premium price is justified by its quality is a matter for debate.

Arabica trees flower best when stressed by a dry spell, as hormones generated by lack of water signal the plant that it's time to ensure the continuation of the species. In modern agricultural practices this can be adjusted through the use of selective breeding and irrigation, but the best coffees still come from trees left to their own natural cycles. Unfortunately this means that one small branch can have ripe cherries, green cherries and flowers, all at once. The only way to pick such trees is by hand, making labour costs a significant factor.

Robusta beans can usually be identified by their shape. The flat side is relatively circular, with a distinct straight cleft down the middle. The bean itself is almost a hemisphere from a side view. Arabicas, flat side uppermost, are more elongated, with an oval tending towards rectangular shape. The centre cleft is uneven, and the side view like half a squashed ellipse. Of course, being natural products, there are plenty of size and shape variations within these descriptions, but they are fairly accurate. Both Robusta and Arabica also have many subspecies or cultivars, and there are also hybrids (both natural and artificial) of the two varieties.

Maragogype beans are from a mutant Arabica variety. They are very large, squareish in shape and normally finer in flavour (in my experience) than ‘ordinary’ beans from the same area. Peaberries, on the other hand, occur in all Arabica types, and are formed when a coffee cherry produces a single, joined seed rather than two "half" seeds. A Peaberry bean looks a lot like a little football. They tend to be denser (higher specific gravity) than similar beans from the same tree, and are prized for the flavour difference this gives, again a bit more refined than the average.

Coffee beans are often graded and priced according to size (bigger = better), freedom from obvious defects, colour etc. but only rarely by overall taste. This sometimes means that some beautiful looking, large defect free beans can command high prices but taste ‘orrible. And small, varicolored beans with all sorts of visible defects can taste spectacular…Yemeni Mochas come to mind. The general public often equates expensive with good, but as with wines the price of a coffee is not necessarily a guide to its quality. This can really be judged only after roasting, in the brewed cup. Some coffee growing regions don't get the publicity they deserve, because they're a long way from the centre of the coffee universe (New York, where else?) Sometimes U.S. political considerations get in the way (Nicaragua and Haiti a few years ago, Cuba today).

Whatever the reasons, comparitive cuppings of the world's most expensive coffees, Jamaican Blue Mountains and Hawaiian Kona vs. the rest of the world, usually result in "other" coffees being rated higher, at a quarter of the price or less. Very expensive coffees rarely have the taste to back up the price, in my experience.