Growth of plant tissue is driven by the turgor pressure inside each cell. The more cell walls yield to the pressure, the faster the tissue grows. The extensibility of the walls depends on its cell wall fibres, whose synthesis is guided by microtubules. Microtubules are filamentous proteins that continuously interact with each other within cells, creating a highly dynamic pattern.
Genes may influence these patterns and in that way influence rates and directions of growth. Directions of growth may be guided by proteins at different ends of the cell, giving each cell a polarity.
If regions try to grow in different directions we end up with directional conflict which can be seen in the patterns of cell files in a tissue.