The present paper focuses on the aquatic and Nanocyperion vegetation of the Danube flood­plain. Most of the data show the results of the surveys in 2019 at low water levels. The Nanocyperion and aquatic vegetation of the Komárom-Esztergom County section is relatively well researched com­pared to the Fejér County section which was previously poorly known. In the last decade, two rare spe­cies – Hippuris vulgaris and Hydrocharis morsus-ranae – have disappeared between Gönyű and Neszmély (Komárom-Esztergom County). In contrast, several new invasive plants have appeared: Salvinia molesta, Myriophyllum aquaticum, Limnobium laevigatum, and Crassula helmsii (first record from Hungary). Vallisneria spiralis and Elodea canadensis were detected again after several decades. Elodea nuttallii and Azolla sp. have become more widespread and abundant than previously. New and uncommon Nanocyperion species were the native and protected Lindernia procumbens and the inva­sive Lindernia dubia. New invasive plants in the studied Danube sections were: Cyperus esculentus, Euphorbia maculata, and Eleusine indica. The native Veronica catenata and Schoenoplectus triqueter have become more wide­spread than before. Polygonum graminifolium was an interesting find of open pebble surfaces in several parts of the examined area, which has no recent records in Hungary from before 2015 (published here).