This study investigated the quantitative anatomy of photosynthetic tissues (leaf mesostructure) of wild ginseng Panax ginseng C.A. Mey. (Araliaceae) plants from different natural habitats. The structural and functional traits of the photosynthetic apparatus shown to be especially elastic were mesophyll cell volume (Cv >40%) and traits related to filling of the leaf with cells and plastids (Cv≥21%). P. ginseng possesses relatively few cells per leaf area (44.6-107.2 103/cm2) and chloroplasts (1.7-4.9 106/cm2). Also low are the values of such integral indexes as relative surface of mesophyll cells (Ames/A, 2.78-5.28) and relative surface of chloroplasts (Achl/A, 1.9-3.2). The leaf mesostructure of wild ginseng shows traits of a plant typically found in shady forest habitats. The photosynthetic apparatus of ginseng adapts to various habitat conditions on the level of leaf mesostructure, through structural transformations of mesophyll tissue, such as changes in the number and size of cells and chloroplasts and also the integral surface indexes Achl/A and Ames/A.