الفهرس 
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Abstract
L. serriola is a winter-spring active annual weed. The stem ascending up to 160 Cm. the lower leaves are pennaty lobed while the upper leaves are entire, become smaller upwards and characterized by spines along the midrib on the lower side.The upper leaves often in vertical orientation. Flowers are yellow radiated arranged in capitula. The seeds Adapted for wind dispersal, Ex. of the cross-sections showed the stem, leaf and root showed that, the stem has the anatomical characters of herbaceous dicot stems. The leaf is dorsiventral with mesophyll tissue distinguished to palisade and spongy tissues. The root was diarch with normal secondary thickness. chromosomal investigation revealed that, L. serriola has 2n=18 chromosomes. The veget-ation assemblage of L. serriola. community comprises 32 species belong to 27 genera and related to 15 families, The main six families which contributing collectively about (64.4 %) of the total number of the recorded species. Poecea comprises 6 species (18.75%), Astereceae includes 9 species (27.27%), Polygonaceae, Chenopodiaceae, Brassicaceae and Amaranthaceae are includes 2 species each (6.25%). Other 9 families contain single of each (3.125%). The recorded species include annuals (71.87%), biennial species (3.13%) and perennial species (25%). Regarding to the Life-form spectra, the majority of species are therophytes (75%), followed by geophytes (12.5%), chamaephytes (6.25%) and finally nanophanerophytes and helophytes represented by a single species (3.125%) each. L. serriola community type involved 17 species or about (30.82%) of the recorded species are Mediterranean taxa. Other chorotypes include Irano-Turanian (12.2%), Euro-Siberian (15.48%), Saharo- Sindian (11.55%), Cosmopolitan and Sudno-Zambezian (7.75%) and Pantropical (3.5%) The soil supporting L. serriola habitat composed of fine and medium sand with a high percentage of silt, low moisture content (4.16%), average porosity (45.36%) and maximum water-capacity (48.16%).The percentage of organic carbon was high (0.91%),while calcium carbonates (6.54%). The total soluble salts content was low (0.05 - 0.35%), mostly sulphate (0.12-0.32%) and bicarbonate (0.018 - 0.024%) while chlorides were lower (0.01-0.04%). The soil reaction is weak alkaline to neutral soil ( pH = ranging 6.75-8.03). It may be concluded that, L. serriola is often adapted to stressful environments and the plant enable to withstand environmental stresses. Seed germination experiments showed that; germination decreases by the increasing of salinity percent and the saw lettuce is non-resistant to the saline soil. The phytochemical analysis of plant parts of L. serriola showed that, it contains proteins, lipids, non- reducing sugars and total carbohydrates that make it an unconventional animal feed. The plant contains Phenols, Flavonoids, Alkaloids and Tannins that can be used as raw materials in the fields of drugs, medicine and industry. Methanolic, Ethanolic, Acetone and aqueous extracts have been shown antioxidant , antimicrobial activities. The present study provides a detailed description of biological aspects, Biogeography, seed germination, salinity tolerance, ecological characteristics, phytochemical constituents, antioxidant and antimicrobial activities of Lactuca serriola. Key words:. Description of biological aspects, Biogeography, seed germination, salinity tolerance, ecological characteristics, phytochemical constituents, antioxidant and antimicrobial activities of Lactuca serriola:.