Weed flora of water rice in the Red River Delta, Vietnam

The occurrence of weeds in water rice was surveyed in the Red River Delta, Vietnam during spring and summer rice-growing seasons in 1995 and 1996. Six ty different weeds from 19 plant families were recorded. The most important plant families as weeds of rice were Poaceae and Cyperaceae. The most impo rtant weed however was Rotala indica (Willd.) Koehne (Lythraceae) followed by Echinochloa crus-galli (L.) Beauv. and Cyperus difformis L. A brief comp arison of this rice weed flora and those of Australia and California was ma de.