Trapetum natantis Muller et Gors 1960 in hydromeliorative facilities in Serbia

Trapa natans is one of the very few plants that generate so many contrasting views: it is highly endangered in Europe, invasive in North America and Australia, yet highly valued in India and China due to its nutritional and medical properties. Its endangered status in most of the Europe has prompted significant conservation efforts aimed at retention and expansion of its population. T. natans is currently on the red list of many European countries and is included under Appendix I of the Convention on the conservation of European wildlife and natural habitats (Bern Convention) and IPA list (IPA criterion A, threatened species). The unusual circumstances, i.e. endangered status of T. natans in the region on one hand and its expansion in Serbia on the other, are the reason behind this research that aims to present the distribution, floristic composition and ecological conditions of ass. Trapetum natantis stands in hydromeliorative facilities (Serbia), comprised of 28 hydrophytes. In the analyzed stands, based on the long-term phytocenological studies, we have singled out four floristic and ecological groups: the stands in which T. natans predominates, the stands with Ceratophyllum demersum, the stands with lemnids plants (Lemna minor, L. gibba, Spirodela polyrrhiza) and Salvinia natans and the stands with Hydrocharis morsus-ranae. In the researched localities, the differentiation of ass. Trapetum natantis stands is predetermined by the phosphorus and nitrate content, as well as pH and BOD5 levels.