The coffee tree root system consists of five types of roots: the central tap root, axial roots, lateral roots, feeder bearers, and root hairs. In a recent field project at SICC labs, we compared the root systems of Robusta and Excelsa coffee plants.
A more comprehensive study of the root system would require a larger dataset for comparison, but these two specimens are fairly representative of their species.
We carefully dug out an Excelsa plant and a Robusta plant, keeping the root systems intact. Both plants were planted at the same time, in the same block, and next to each other. Plants with deep tap roots are better able to access water and nutrients from deep in the soil. This is especially important during periods of drought, when surface water is scarce. Deep tap roots also help to anchor plants in the ground, making them more resistant to wind and erosion.