The first aspect noticed in the appearance of plants is usually their colors,which is associated with human reactions to their visual characteristics.Therefore,color plays an important role in the promotion and public suitability of forest scenic beauty.This paper summarized the milestones in chromatics formation and research trends of plant color over the past century.The developing course of plant color research can be divided into germination,formation,evolution,and flourishing periods.Simultaneously,the main characteristics of each stage have been analyzed.The mechanisms of expression generated by plant color and the relevance between color and human reactions were reviewed through four visual scales,including plant organs,individual plants,population and community of plants,and overall landscape.In this review,three levels of influence including aesthetics,physical,and mental,were identified.Several defects on plant color extraction,such as color element ration,feature factor selection,and color quantization were detected and through them,five key directions were elucidated for future research:1) analysis of the association between plant colors and different scales as well as human reactions to them;2) in-depth study on plant color evaluation factors in a large scale;3) multidisciplinary fusion of the color quantization method;4) comprehensive comparison of public reactions to plant color;and 5) practice of forest scenic beauty promotion.The present study will contribute to a comprehensive understanding of the mechanisms and influences of plant color expression,as well as scientific studies on plant color under different precisions and scales.