- The generalised growth of woody species and their response to defoliation is presented to provide a conceptual background for an examination of the growth of Acacia karroo and its response to defoliation. Particular attention is paid to water stress and the role it plays in determining the conditions of existence for woody plants. The nutritional and hormonal control of growth in woody plants is considered. Carbohydrate reserves are important in regrowth, but even where carbohydrate supplies appear to be adequate, growth is inhibited. In such cases a deficiency of plant hormones may account for this inhibition. Water stress that inhibits growth does not necessarily reduce carbohydrate reserves. The ontogeny and annual growth cycles of A. karroo are given and possible reactions to water stress and defoliation are outlined. 1980 Taylor & Francis Group, LLC.