Photosynthesis, the process by which green plants synthesize carbohydrates from the carbon dioxide available in the environment using light energy as a fixed energy source with the help of photoassimilate pigments, underlies all food chains in nature. The good functioning of plants (in this paper, spontaneous and cultivated taxa of the genus Taxus L.) in their vegetation areas is influenced, at the same time, by the level of their relationship with the environment regarding water exchange, as a vital factor for the existence of the vegetation cover on Earth. As a result, the basic physiological processes (photosynthesis, transpiration) depend to a large extent on the anatomical and micro-morphological characteristics of their leaf apparatus, on certain internal factors relating to the leaf surface, and on a series of external factors, which manifest themselves in the environment of the taxa concerned, to which they have developed specific morpho-structural and functional adaptations.