Abstract: Application of native and genetically modified species is one of the main approaches to revival and modification of ranches. But in the mean time, it should be noted that those species that are compatible to each other should be used in vegetation expansion projects. Shiraz oregano (Zataria Multiflora) is from among those plants which could cause allelopathic effects due to their various chemical compositions. Hence, due to profusion of this plant throughout the Khalil Beig ranch of Arsanjan, and the considerable amount of Stipa Arabica and Cymbopogen Olivieri in the adjacent areas to this ranch that are consumed by the livestock, it was decided to study the possibility of applying the aforesaid species for expansion of vegetation throughout the Khalil Beig ranch. To this end, an investigation was conducted in the greenhouse environment using the soil taken from the habitat of Shiraz oregano. Underground and aerial parts of this plant were collected and extracts of 25, 50, 75 and 100 percent as well as 50 and 100 % densities were obtained from aerial and underground parts, respectively. Also, a bittern was considered as the prototype (distilled water). Seeds of Sarabica and C.olivieri were cultivated in flower pots containing the soils of oregano habitat and were irrigated using the abovementioned bitterns throughout the entire study. The investigations lasted for 5 weeks and the germination and growth rates of seedlings were recorded on a daily basis. In the end, characteristics of both species such as percentage of germination, length of stem, length of root, wet weight of stem, wet weight of root, dry weight of stem and dry weight of root affected by different density percentages of Shiraz oregano extract were analyzed through variance analysis. The Duncan test was applied for comparison of means. The results represented the preventive effect of compositions existing in Shiraz oregano on the studied features and the less vulnerability of S.arabica as compared with the C.olivieri
