Abstract

Argemone ochroleuca is an invasive worldwide medicinal plant with economic potentialities. The species is largely distributed in Taif Governorate, KSA. Its introduction affected the flora of the area hence, the study aimed at elucidating the effects of its infestation at nine localities representing three different habitats, sand plains (such has in Al- Shafa, Jabajeb, and Al-Arafah), dams (as in Gadeer Albanat and Ekrima) and wadies (such as in Thumalah, Wadi shab, Saysed and Jaleel). The importance of the study in Taif Governorate is exemplified in high salt accumulation, scanty rains and high evapotranspiration of the studied area. The reason for studying the Argemone communities arises from the fact that they occupy virtually every habitat where extreme conditions keep out other forms of life. The species is characterized by its high propagation ability that affects to a large extent - the rangeland ecosystems. In this study, some of the characteristics of the natural vegetation cover in the chosen localities were examined, such as the floristic composition of species inhabiting the Argemone communities, their important values and the physico-chemical analysis of the inhabited soil. Also, a detailed study of the pheonological changes of A. ochroleuca was monitored during the year, 2008/2009. A number of 35 desert weed species, with different life forms and belonging to 25 different families were associated with Argemone. Among these species, Argemone preponderated and attained the highest importance value of 180 at Al-Arafah locality. Following the phenology of Argemone, results revealed that its life history is completed within eight months. Seed germination takes place in December, vegetatively grows in January, flowers in March and April and disperses seeds in May, June and July.

Key words: Invasion, importance value, floristic composition, phenology.