The Coffee Tree
Although usually referred to as a tree, coffee is actually an evergreen shrub. If left unpruned, it would reach a height of 14 to 30 feet (3-9 meters). Its leaves are dark green and glossy on top and a lighter, duller green underneath. They are 3 to 6 inches (7-15 cm) long and grow opposite each other along the branches. At the points where the pairs of leaves join the branches, many small white blossoms appear at the time of flowering and give the coffee plantation the appearance of being covered with light snow.
The fragrant blossoms fall within a few days and small berries develop that change from dark green to deep crimson as they ripen. The berries ripen about 6 to 7 months after the tree has flowered. Beneath the skin of the berry is a fleshy pulp and within the pulp is a parchment-like covering that encloses the green beans— usually 2 in each berry. The green beans have a delicate, tight-fitting, almost transparent skin.
Coffee trees usually bloom once a year, although they may bloom more often in very rainy climates. The trees often have flowers, green berries, and ripe berries on their branches at the same time.
Coffee trees normally begin to bear within 5 years of their initial seeding, and yield good commercial quantities of beans within 8 years. The trees produce at an optimum level for 15 to
20 years, but may continue to bear commercial amounts for many more years where soil conditions are favorable. Annual yields of 1 to 1 1/2 pounds (0.5-0.7 kg) of green beans per tree are considered adequate, but they are frequently higher.
While there are 20 or more commercial species of the genus Coffea, only 2 coffee trees, C. arabica and C, robusta, are raised in quantity for beans. Very few C. liberica are raised because of the poorer taste qualities of the bean. Arabica generally is preferred to other types of coffee because of its mild, rich flavor. Until the middle of the 19th century it was the only variety cultivated. But because arabica is subject to attacks by insects and disease, the more resistant robusta and liberica species were subsequently developed.