In the last decades in Hungary biotopes of Nanocyperion species have been reduced significantly according to the melioration and the declining of pasturing. Owing to the habitat loss more species such as the examined Lindernia procumbens, Eleocharis ovata, Centunculus minimus, Limosella aquatica, Juncus sphaerocarpus and Elatine triandra became endangered all over the country. During the researches site requirements of these species were analysed as well as their connection with the cultivated species and the soil cultivation carried out on the plough-lands. According to our experiences in West Hungary actual occurrences of Lindernia procumbens, Centunculus minimus, Juncus sphaerocarpus and Elatine triandra are related strongly to the plough-lands. Eleocharis ovata and Limosella aquatica occur on plough-lands less frequently, exist mainly on other pioneer moist habitats. It can be established in case of all the 6 examined species that their habitat spectrum has extended by the increasing in the territory of ploughs forming spacious convenient biotopes for these species. © Eugen Ulmer KG.