Abstract
In the presence of 10-2 M hydroxyurea cell division is prevented but cell growth continues. The rate of cell growth varies within the apex, depending on the location of the cell. The rate of growth is low in the quiescent centre and non-dividing region of the root cap but higher elsewhere. Indolyl acetic acid causes a transient increase in the rate of cell enlargement but after about 12 hours has no further effect.