Abstract The supply of auxins [2,4-dichlorophenoxy acetic acid (2,4D), indole-3 acetic acid (1AA) and α-naphthaleneacetic acid (NAA)] to excised chicory roots induced the formation of lateral root meristems mainly located close to the pre-existing apical root meristem. Lateral root growth induced in non-excised roots required higher auxin concentrations. Inhibition of root elongation and concomittant enlargement of the apices was also observed. Supplying IAA induced the formation of lateral meristems earlier than NAA, but subsequently favoured root elongation. Conversely, in the presence of 2,4D, reactivation of pericycle cells was very intense, but conversion of primordia to laterals was inhibited. Regardless of the auxin used, the responsive area in which lateral meristems appeared was located a maximum of 4 mm away from the apical meristem. This region remained devoid of any lateral root formation under control conditions. Pericycle cells opposite the xylem poles in the diarch stele regained meristematic activity and divided transversally, giving rise to shorter cells. These cells subsequently divided periclinally, forming pairs of cells on the same transverse level. The root primordium extruded through cortical cells and was surrounded by a lacuna formed to the detriment of cortical cells.