The analysis of the main weeks of Lithuanian macrophytes reserchers, classification of rivers and the main types of grows of the rivers with plants are presendet in the work. The Mūša river hadn’t been investigated from the standpoint of botany yet. It begins 5 kilometers avay from Juodeikiai in the western port of the Mūša Tyrelis (by Taminskas, 1997). The Mūša river was reserched in 157 kilometers long. The botanical reserches were carried out ofter the methodics of general macrophytes investigation (by Katanskaja, 1981). It was used Brown-Blanquet (1964) or the so-called Zurich-Montpeljė school researches of floro and principles of classification, then too synthatical code to pick out associations (by Balevičienė, 1991; by Pott, 1992). Macrophytes make up zones till 4 metres Width in the Mūša river. Longer areas in the river take up such associations: Potamogetonetum pectinati, Phragmitetum australis, Typhaetum angustifoliae, Phalaridetum arundinacea. In order to clear up the arrangement of various macrophytes ecological groups and their forming associations, there were fulfilled 5 vegetation side-views in Mūša river. 68 species of macrophytes that belong to 26 families ant 49 genus were inventoried in the Mūša river. The following families distinguish the lorgest specific variety. These are Cyperaceae (9 species), Poaceae (8 species), Lamiaceae (5 species), Polygonaceae (4 species), Apiaceae, Scrophulariaceae and Lemnaceae (3 species). The associations that, were... [to full text]