In the present work, some of the adaptive responses against dehydrative factors were evaluated in two true xerophytic plants, for their medicinal importance; [Launaea spinosa (Forssk.) Sch. and Leptadenia pyrotechnica (Forssk.) Decne.] growing naturally (wild plants) at Wadi Hagul, Eastern Desert of Egypt during both wet and dry seasons. The results reveled that  Launaea spinosa achieved the highest significant ash concentration during the dry season and this was mainly due to accumulation of Na⁺, K⁺, Cl^- and SO₄^2-, meanwhile the opposite was found in Leptadenia pyrotechnica, which accumulated Ca²⁺, Mg²⁺ and P³⁺ during the wet season. The highest significant concentrations of total carbohydrates, insoluble sugars as well as phytohormones were recorded during the wet season, while organic acids, free thiols, total fibers, and soluble sugars were accumulated, in both species, during the dry season. From the results it is clear that, ethyl acetate extracts for both species possessed the highest antimicrobial activity against all tested fungal and bacterial strains. The obtained results showed that the studied species have different mechanisms to adapt and tolerate the various environmental conditions.