Plant growth and development can be coordinated by numerous molecules produced by plants. An example of such a molecule is cis-cinnamic acid (c-CA). Currently, c-CA is known to inhibit the transport of auxin, a major plant hormone. This inhibition in transport causes the levels of auxin to increase in the tip of the root, resulting in more lateral roots and a bigger overall root architecture in the c-CA treated plants. Due to the larger root architecture, the plant is better capable of taking up nutrients from the soil, which is reflected in an increase in overall plant biomass. Although c-CA is a natural compound shown to be present in plants, it is not known which role it has in steering plant growth and development. Further research into this molecule can serve as a stepping stone to provide answers to this intriguing question. The main goal of this PhD project is to fill in the gaps concerning c-CAs mode of action and its physiological relevance in plants. The central questions we aim to answer relate to the where, what and how of c-CA, and more specifically (i) where c-CA is made in plants, (ii) what happens in the plant when the amount CA is increased or decreased, and (iii) how c-CA is influencing plant growth and development on a molecular level. The answers to these key questions will bring forth a better understanding of the processes coordinated by this intriguing naturally occurring growth-promoting compound.