For successful crops, the two major forms of coffee grown in the world today, Arabica and Robusta, need between 1500 and 3000 mm of rainfall per year. Droughts, frost, and high-winds can all impact a season’s harvest in any given area, which affects coffee stocks and prices. The trees also do not produce well in extremely hot weather. In fact, the ideal annual mean temperature is around 70 degrees F. Coffee trees produce berries at different times of the year, some with multiple harvests per year, depending on the location. For example, in Java, harvesting is practically continuous through the year while in Colombia there are two picking seasons, the main and the mitaca (the fly.) Coffee trees grow to between 15-30 feet, but are often pruned to reduce height for ease of picking. The leaves are dark green, shiny, elliptical-ovate in shape, and grow opposite and alternating one another. Robusta coffee trees depend on cross pollination, while the Arabicas are self-pollinating. Small white flowers, with a fragrance similar to jasmine, bloom in bunches just before the green coffee cherries appear. The flowers bloom for only a few days. The green cherries appear in clusters, and turn to yellow, orange, then red, and finally to a full deep red when they are mature and ready for harvest. The maturation from green to red takes about thirty to thirty-five weeks, although not all cherries on a tree or in a crop mature at the same time. The outside layer of the coffee fruit is a skin called the pulp. The next layer is mucilaginous and surrounds the two beans. In addition to this layer surrounding each bean individually, there is a tougher “parchment” as well as an inner, more delicate “silver skin.” The beans of Arabica and Robusta plants have two distinguishable shapes: The Arabica is a flat, oblong bean with a crooked furrow, while the Robusta is rounder and convex with a straight and even furrow through the center of the bean.