Dendritic organic heterojunctions with aluminum tris(8-hydroxyquinoline) (Alq(3)) microwire trunks and 1,5-diaminoanthraquinone (DAAQ) nanowire branches were prepared by a two-step growth process. The prefabricated Alq(3) microwires act as nucleation centers for site-specific secondary vapor growth of DAAQ nanowires, resulting in the unique dendritic heterostructures. When the trunk was excited with a focused laser beam, emitted light of various colors was simultaneously channeled from the branched nanowires via both waveguiding and energy transfer. The intensity of the out-coupled emissions was modulated effectively by changing the polarization of the incident light.