The consequences of various old-time and recent human interventions on the Danube river (‘the most international river of the world’) are enormous, and still, new developments are planned. Therefore, we targeted to explore the current vegetation of the islands on the Hungarian Danube stretch between Vének and Budapest (149 river-km long), and the reasons for their various appearance. The first pioneer habitats on riparian zones of islands and gravel bars where the surface becomes dry are willow scrubs. Purple willow scrubs (Rumici crispi–Salicetum purpureae association) evolves on gravel-covered surfaces characterized by extreme water regime. Such surfaces were typical on the riparian zone of the islands along the main flow, and upper zones of the side-arm bank on the islands. On the contrary, almond-leaved willow scrub association (Polygono hydropipero–Salicetum triandrae) develops on silty and sandy surfaces, which is typical along side-arms, mainly in their lower riparian zone. As a consequence of closing the side-arm (due to water regulation purposes), previously gravel-covered surfaces of its riparian zone have been recently covered by smaller sediments of sand or silt, and thus, the Rumici crispi–Salicetum purpureae association only appears on the bank of the islands along the main flow. However, many erosion protection structures were built along the riparian zone which blocks the development of continuous stands, and therefore, the next successional stage (black poplar stands) cannot evolve. Almond-leaved willow (Salix triandra), the dominant species of almond-leaved willow scrub stands (Polygono hydropipero–Salicetum triandrae) becomes rare as well; its consociation with white willow (Salix alba) are more typical, or the white willow stands (Leucojo aestivi–Salicetum albae) grow directly on the bank without any scrub association. A possible reason for this might be the deepening water-level and drying of bank zone along the side-arm.