Abstract
Morphological, anatomical and physiological plasticity was examined for Cakile arabica from three different sites at the coastal part of the Arabian Gulf near Ad Dammam city in the eastern region of Saudi Arabia. Morphological investigation showed that the size and number of lobes of the leaves are increased in sites (I) which have high salt stress. Also anatomical investigation using a light microscope showed that the plant is adaptive for salt stress by increasing the thickening of the cuticle or epidermis layer and increase in the area of vascular bundles. Physiological studies showed that plant growing under high salt stress is characterized by increase content of electrical conductivity and increase in chlorophyll a, b, carotenoids and proline content in the plant tissues. This can be explained as an osmotic adjustment mechanism for the investigated species growing under high salinity stress.