As the vertical elongates, two laterals are produced at each new node. The elongation of the vertical and lateral branches is most rapid during the summer months. During cool or dry months without irrigation, growth stops. When new growth resumes, the vertical will grow taller, while the laterals, in addition to growing longer, will produce new laterals on the previous season's growth. These lateral branches that grow from the main or first side-branches are called secondary laterals, while the main side-branches that grow at the nodes of the verticals are called primary laterals.
As the cycle is continued, the primary laterals produce more secondary laterals, and the secondary laterals themselves produce additional branch laterals: tertiary laterals. These will in turn produce further side-branches if the tree is left unpruned. For the sake of convenience, all laterals with the exception of the primary laterals are usually called sublaterals. Thus, as the coffee tree gets older, the main vertical becomes surrounded by a mass of intertwined and crossed sublateral branches.
Flowering and fruiting occur at the nodes of the laterals and rarely on the verticals. Under normal conditions, flowers are produced only once at each node. Fruits (cherry) on the verticals are few and inconsequential, while good fruits are produced at every node on the bearing wood of the laterals if sunlight is adequate; heavy shade results in a node with few or no flowers.
j Coffee trees grow taller and wider by the growth of both the verticals (taller) and the laterals (wider) (see Fig. 2, p. 26). The new growth on laterals is called growing wood. Fruit clusters appear at the nodes of this new growth during its second year, when it becomes known as bearing wood. While fruit is maturing on the bearing wood, new growing wood for the next crop is being produced at the end of the lateral. The size of the next crop will depend upon how much growing wood is produced during any given year, or, more exactly, on the number of new nodes on laterals.
Because the growing wood is being produced while the fruit is maturing, the tree is taxed for nutrition simultaneously by the growing wood and the developing fruit. As a result, when the tree is overloaded with fruit, very little growing wood is produced. Because the next year's crop is produced on this year's growing wood, overbearing during one year results in a small crop the next year.
On the other hand, if the crop is small this year and the tree is able to produce more growing wood, the result will be a larger crop next year. This tendency of bearing a heavy crop one year and a light crop the following year is commonly called biennial bearing.