Abstract:Aims Although Caragana davazamcii is an important nitrogen-fixing plant in North China, few studies have focused on its epidermal structure and genetic diversity along a precipitation gradient. Our aims are to determine how changes of epidermal structure of C. davazamcii leaves are related to changes o f genetic diversity in different habitats, what role environments play in this relationship, and whether these populations have potential to become adapted to their local environments in different ways. Methods We established 20 m×20 m plots along the precipitation gradient and randomly collected leaves of C. davazamcii from natural populations. We studied leaf epidermal structure using a light microscope (LM) and a scanning electron micro scope (SEM) and used ISSR-PCR genetic diversity analysis to study differentiation among populations. Important findings The leaf epidermis of C. davazamcii in different habitats was significantly different as a result of environmental effects. Trichome density, stomatal density, stomatal index and cuticle coarseness increased with changes in average annual rainfall from east to west, as did genetic diversity of populations. Caragana davazamcii showed significant phenotypic plasticity in different habitats, and this may play a critical role in the ecological adaptability of C. davazamcii populations.