This research was about a comparative taxonomic study about Peganum harmala which belong to Zygophyllaceae family, The effect of dam Al-Adheems water on the growth of this plant has been clarified at Al-Shay Al-Sagheerl Himreen regionl Salah Al-Din, it was found that this plant is adapted to live near and far from water at the same time. The phenotypic traits included study the traits of the stems , leaves ,flowering heads and the quantitative and qualitative reproductive organs ,it turns out that this traits have a great taxonomic importance ,the diversity of this traits have been discussed .the traits of vegetation have been studied in terms of amount of Peganum harmala was (5%) in region (A) which is close to water ,which affected of dam Al-Adheems water, while it was (40%) in the region far from water, region (B), whereas the density of Peganum harmala was (17) 100 / m2 in the region close to water , while it was (82)100 / m2 in the region far from water, whereas the frequency of Peganum harmala was (41) in the region near the water ,while it was (83) in the region far from water.