Coffee grows on a coffee plant; this plant is part of the Rubiaceae-family. There are many sorts of coffee plants, but the ones that are used for consumption are Coffea Arabica and Coffea Canephora (Robusta).
Other sorts like Coffea Liberica and Coffea Excelsa are not used for consumption, because of the bitter taste and very high caffeine levels. These two are mostly grown in Indonesia and Malesia. Back at the end of the 19th century, the Arabica trees were ruined here by a rust disease, and therefore the farmers were forced to grow other kinds of coffee plants, like Liberica. This coffee was also very interesting for travelers, so they were able to stay awake for hours. Now, the locals still drink Liberica.