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Abstract The p r e s e n t s t u d y aims a t d e s c r i b i n g t h e s p a t i a l v a r i a t i o n i n t h e weed f l o r a a s s o c i a t e d with s i common crops gypti ti an c l o v e r , Broad beans, Wheat, Cotton, Maize, and Rice) i n t h e Nile Delta r e g i o n . It d e p i c t s t h e weed communities a s s o c i a t e d t o t h e s e crops and a s s e s s e s t h e r e l a t i o n s h i p s between t h e p r e v a i l i n g environmental r i a b l e s on one hand, and t h e weed communities and t h e i r v e g e t a t i o n a l v a r i a b l e s on t h e o t h e r hand. Two hundred and twenty one r e l e v b s (1091 monthly o b s e r v a t i o n s ) were sampled over two growing seasons (1984/1985 and 1985/1986) f o r r e p r e s e n t i n g t h e weed v e g e t a t i o n of t h e s i x common crops i n f i v e l o c a l i t i e s d i s t r i b u t e d i n t h e study a r e a . These l o c a l i t i e s a r e : El-Hamool, Kafr E l - Z i a t , Tanta, Berket El-Sabaa, and Quwesna. In each r e l e v b , a l i s t of s p e c i e s , t h e i r phenological s t a g e s and t h e i r l i f e forms were r e c o r d e d , and a composite s o i l sample was c o l l e c t e d . The phytomass2 (gm dry matter/m ) of t h e weed s p e c i e s was e s t i m a t e d , using t h e d i r e c t h a r v e s t from random q u a d r a t s , i n some s e l e c t e d releves (78 r e l e v b s ) f o r r e p r e s e n t i n g t h e r e l a t i v e importance value of t h e weed s p e c i e s . |