الفهرس 
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Abstract
The present work deals with the study of the ecology and economic potentialities of Achillea santolina and A. fragrantissima growing naturally in Egypt and aims at the following objectives: - Study of the floristic features including record of plant species, life-span, life from spectra and floristic categories of the wild species in the study area to detect the taxonomic and phytogeographical significance of its floristic component, analysis of variation in the environmental factors (edaphic) to determine the soil factors controlling the abundance and distribution of the recognition weed communities in the study area and evaluation of the economic potentialities of the selected plant species (Achillea santolina and A. fragrantissima) growing naturally in the study area by studying: phytochemistry, antioxidant and allelopathic activity.The area chosen for the present study is located in the Western Mediterranean coastal belt (Mariut coast) and North Isthmic Desert (Wadi Hagul). The results of the present study indicated that, the total number of the recorded plant species in the present study is 74 species belonging to 66 genera and related to 23 families. The recorded species include 42 perennials (56.75%), 31 annuals (41.89%) and one biennial species (1.35%). According to the life- from spectra, therophytes (41.89%), chamaephytes (24.32%), hemicryptophytes (18.92%), phanerophytes (10.18%), geophytes (4.05%) and helophytes (1.35%). The floristic analysis of the study area reveals that, 23 species (31.08%) are Saharo-Sindian. Twenty five species are Mediterranean Taxa. It has been also found that, 5 species (6.75%) are cosmopolitan, 8 species (10.81%) are Saharo-Sindian and Sudano-Zambezian and 8 species (10.8%) are Iran-Turanianand Saharo-Sindian. Pantropical, Palaeotropical, Neotropical and Sudano-Zambezian are represents by one species each. The phytochemical analysis of two species (Achillea santolina and A. fragrantissima) which are growing naturally in the study area have been studied.The quantitative determination of the secondary chemical constituents (tannins, saponins, flavonoids, alkaloids and phenolic) has been determinates. DPPH free radical scavenging activities were also estimated. The allelopathic bioassay of Achillea santolina and A. fragrantssima were investigated by studying the phytotoxic effects of their methanolic extracts on seed germination and seedling development (shoot and root) of the Portuleca oleracea.