الفهرس 
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Abstract
The area chosen for the present study is located in the Nile Delta (canal bank and Deltaic Mediterranean coast) and inland desert (Cairo-Suez desert road and wadi Hagul) of Egypt which covers the six Governorates namely: Damietta, El-Dakahlia, Kafr El-Sheikh, El-Behira, Cairo and Suez. The total number of the recorded plant species surveyed in the present study is 182 species belonging to 144 genera and related to 37 families. Out of these families, Asteraceae, Poaceae, Chenopodiaceae, Fabaceae and Brassicaceae were considered the major families as they contribute collectively about 55.50% of the total number of recorded species. This indicated that, these five families are leading taxa and constitute the major bulk of the flora of the study area. These recorded species include 82 annuals (45.05%), 3 biennials (1.65%) and 97 perennials (53.30%).According to the life-forms of the flora of the present study are grouped under six types as follows: therophytes (85 species = 45.21%), cryptophytes (32 species = 17.02 %), chamaephytes (30 species = 15.96 %), hemicryptophytes (26 species = 13.83%), phanerophytes (11 species = 5.95 %) and parasites (one species = 0.53%).The floristic analysis of the study area revealed that, 88 species or about 48.35 % of the total number of recorded species are Mediterranean taxa. These taxa are either Pluriregional (38 species =20.88 %), Biregional (30 species =16.48 %) or Monoregional (19 species = 10.44 %). It has been also found that, 38 species or about 20.88% of the total number of the recorded species are either Cosmopolitan (8.79%), Pantropical (4.95%), Palaeotropical (4.95%) or Neotropical (2.20%). On the other hand, the Monoregional Saharo-Sindian element is represented by 34 species (18.68%) of the total number of recorded species. The classification technique applied here was the Two Way Indicator Species Analysis (TWINSPAN), led to the recognition of four vegetation groups. The vegetation analysis of study area habitats, led to the recognition of four vegetation groups. group A was dominated by Retama raetam, group B was codominated by Diplotaxis harra and Bassia muricata, group C was codominated by Senecio glaucus and Rumex pictus and group D was codominated by Cynodon dactylon and Phragmites australis. The quantitative determination of the secondary chemical constituents (tannins, saponins, flavonoids, alkaloids and phenolics) have been determined.The DPPH free radical scavenging activity of the studied plant extract were also estimated. The extract of Nauplius graveolens extract showed strong scavenging activity (IC50 < 1 mg/ml). The allelopathic bioassay of Reichardia tingitana, Nauplius graveolens, Picris asplenioides and Urospermum picroides was investigated by studying the phytotoxic effects of their aqueous and methanolic extracts on seed germination and seedling growth (shoot and root lengths) of nuisance Echinochloa crus-galli.