Plasticity in crown architecture, contributing to leaf arrangement within crown, is an important feature for whole plant
carbon assimilation and survival. In this study, I examined the plasticity in crown architecture to light condition and developmental
stage by the changes in shoot production. Rhododendron reticulatum expands crown with orthotropic
growth in monopodial branching in young stage, but orthotropic growth is ceased in adult stage. Main stem of young
crown is described with monopodial branching regardless of light environment. But multi-layer crown is observed in
sun-lit environment rather than mono-layer crown in adult stage. Long shoot production for each branching system (foliage
derived from sympodial branching) in young crown is associated with local light environment, but not in adult
crown. Long shoot production rate is correlated with long shoot production rate of its mother shoot in young crown, but
not in mono-layer crown. These results suggest that young crown expands branches to sun-lit position whereas adult
crown reduces congestion of shoots with stochastic shoot production regardless of shoot production of mother shoots. I
concluded that both light and developmental stages are important factors for shoot production and constructing crown
architecture.