Coffee traces its origin to a genus of plants known as Coffea. Within the genus there are over 500 genera and 6,000 species of tropical trees and shrubs. Experts estimate that there are anywhere from 25 to 100 species of coffee plants.
The genus was first described in the 18th century by the Swedish botanist, Carolus Linneaus, who also described Coffea Arabica in his Species Plantarum in 1753. Botanists have disagreed ever since on the exact classification, since coffee plants can range widely. They can be small shrubs to tall trees, with leaves from one to 16 inches in size, and in colors from purple or yellow to the predominant dark green.
In the commercial coffee industry, there are two important coffee species — Arabica and Robusta.