Phenotypic plasticity of sylleptic branching: Genetic design of tree architecture

The crown of many trees is composed of a main axis and branches. All branch es arise from axillary or lateral buds and two types of branches exist: pro leptic and sylleptic. Proleptic branches form from buds that have undergone a rest period, typically associated with winter dormancy, whereas syllepti c branches emerge without a rest and without complete bud formation. All tr ees have proleptic branches; some trees with the indeterminant growth habit have both proleptic and sylleptic branches. Sylleptic branches may play an important role in determining tree growth, architecture and adaptation for many temperate-zone woody plants. We review evidence for the phenotypic pl asticity of sylleptic branches and its genetic, environmental, and developm ental control.