There are many types of coffee plants, but there are only two main species of the coffee plant. The two main species of the coffee plant are the Coffea arabica and the Coffea canephora (robusta), whereas arabica is the eldest of the two. Robusta contains 40 to 50 percent more caffeine than arabica, and can be cultivated in environments that are not suited for the growth of arabica, which has led to its use as an inexpensive substitute for arabica in commercial coffee blends. The taste of robusta is bitter and has little flavor, compared with arabica, and has a “burnt rubber” or “wet cardboard” aroma and flavor. The best quality robusta plants are used as ingredients in espresso blends, which provide a better foamy head and lower ingredient costs. Many of Italy’s espresso blends are based on dark-roasted robusta.
The arabica coffees are named for the region of the world they are exported from, with the two oldest being Mocha, from Yemen, and Java, from Indonesia. However, the names have become more specific, telling the country, region, and sometimes the estate the coffee plant comes from. The arabica coffee plant is known for making traditional coffee, and is known to have a much better taste than robusta. Arabica and robusta have sub-varieties, like the way a winery has many different blends of wine. Mocha and Java are the traditional varieties of arabica, while robusta has an exotic and very expensive gourmet variety known as Kopi Luwak. This coffee bean is unique because the beans are gathered from the droppings of the Common Palm Civet, which is an animal whose digestive processes give the bean a distinctive flavor. However, most varieties of coffee plants are not as odd as the Kopi Luwak.
Where a robusta or arabica species of coffee plant is grown, can affect how the plant grows and how the bean tastes. Arabica is a species that is indigenous to Ethiopia, and may also be known as the coffee shrub of Arabia, mountain coffee or arabica coffee. The Coffea arabica is known to be the first species of coffee cultivated, being grown in southwest Arabia more than 1,000 years ago. Arabica is also considered to produce better quality coffee than robusta. It also contains less caffeine than robusta, but is still preferred for its taste, as taste matters more today. The arabica plants grow wildy, and can grow between 7 and 12 m tall with an open branching system. The leaves of the plant may be elliptic-ovate to oblong, and may be 6 to 12 cm long and 4 to 8 cm broad, glossy and dark green. Its flowers are produced in auxiliary clusters, and the flowers are white and approximately 1 to 11/2 cm in diameter.
The fruits of the arabica plants are berries, and measure 10 to 15 mm long, mature to bright red or purple colors and contain two coffee beans. Robusta trees are grown exclusively in the eastern hemisphere, but may thrive in equatorial climates at low altitudes. The plant’s berries require less care than arabicas’ because they remain on the tree after they ripen. The beans of the robusta have twice as much caffeine as they arabica, but the flavor is far less. Most brands of coffee beans found in supermarkets are robusta. Arabica beans are most commonly found in coffee shops. One third of the coffee produced in the world is robusta. Robusta is mostly grown in Africa and Brazil, where it is known as Conillon. It is considered a less quality of coffee, so it is limited to lower grade coffee blends as filler. The robusta beans may also be included in instant coffee, and of course in some espresso blends to enhance the formation of crema(foamy head).