Apical dominance.

Axillary buds usually do not grow due to apical dominance: release of auxin by apical meristems.

  1. Auxin from the apical bud inhibits the growth of axillary buds.

  2. If the apical bud is removed, cytokinins, produced in roots, stimulates the growth of axillary buds and lateral branches.

  3. Applying auxin to the stump suppresses growth of the lateral branches, indicating both hormones play a role in determining lateral growth.