Abstract: Sabina vulgaris has two types of leaves (i.e. spine and scale leaves) . This study examined the differences in structure and function between spine and scale leaves, and hence their ecological significance of change of leaf form in the species, (l) The spine leaves had smaller cuticle thickness, epidermis cell size, mesophyll cell surface area, and vascular bundle size than the scale leaves. (2) Both tissue density and coefficient of water loss were higher in the spine leaves than in the scale leaves. (3) The spine leaves had higher net photosynthesis rate, transpiration rate, and the ratio of substomatal CO2 concentration to atmo-spheric CQz concentration than the scale leaves, but water use efficiency (WUE) was lower in the former than in the latter. Our results suggest that spine leaves had higher photosynthesis product accumulation and water loss than scale leaves, but both resistant - drought and resistant - radiation abilities and WUE were just opposite. Therefore, spine and scale leaves have different structure and function, which allows this species to adapt different environments.

Key words: Sabina vulgaris