Japan, China, S.W. Asia
"The shrub Skimmia japonica... is widely distributed in Japan and its leaves are relatively free from insect attack... the methanol extracts of the leaves and fruit of this plant exhibited an insect growth inhibitory activity against the silkworm, Bombyx mori." 
"Skimmia japonica s. str. is the eastern-most species of the genus and widely distributed in Sakhalin, the Kuriles, Japan and Taiwan in the understorey of various forest types such as coniferous Picea–Abies forests, deciduous Fagus–Quercus forests and broadleaved evergreen forests" 
"Skimmia japonica (Rutaceae) originates from East Asia and is cultivated for ornamental purposes in Europe." 
"Vegetative growth of many species of tropical and temperate woody plants occurs in a series of flushes. Such episodic growth patterns have been discussed by a number of authors in texts on growth and development of woody plants... Many species exhibiting this growth habit produce a number of flushes during the period of active vegetative growth. An exception is Skimmia japonica where only one vegetative flush, followed by a floral flush, is made in a season. Because of this growth habit, Skimmia is slow-growing and this is reflected in its high market value." 
 Reisch, J., & Achenbach, S. H. (1992). A furanocoumarin glucoside from stembark of Skimmia japonica. Phytochemistry, 31(12), 4376-4377.
 Ochi, M., Tatsukawa, A., Seki, N., Kotsuki, H., & Shibata, K. (1988). Skimmiarepin A and B, Two New Insect Growth Inhibitory Triterpenoids from Skimmia japonica Thunb. var. intermedia Komatsu f. repens (Nakai) Hara. Bulletin of the Chemical Society of Japan, 61(9), 3225-3229.
 Fukuda, T., Naiki, A., & Nagamasu, H. (2007). Karyotypic analysis of Skimmia japonica (Rutaceae) and related species. Journal of plant research, 120(1), 113.