We present the diversity of riparian poplar (Populus euphratica, P. pruinosa) forests of the Lower Amudarya from the standpoint of floristic classification. We validated the names of class Populetea euphratica and order Populetalia euphratica and described three new associations belonging to the alliance Populion euphraticae from the studied region. The class Populetalia euphratica, order Populetalia euphratica and alliance Populion euphraticae represent valley poplar forests of arid regions of Eurasia and North Africa. The main diagnostic feature of the class is the dominance of poplars from the subgenus Turanga (Populus euphratica, P. pruinosa). The association Glycyrrhizo glabrae–Populetum pruinosae ass. nov. unites tugai forests of the Lower Amudarya dominated by Populus pruinosa above the Tuyamuyun hydrosystem, as well as in the more watered south-eastern part of the river delta. The association Tamarici ramosissimae–Populetum euphraticae ass. nov. represents forests widely distributed in the Amudarya lower basin. The association Zygophyllo oxiani–Populetum euphraticae ass. nov. represents tugai forests of the Amudarya delta, where ecosystem degradation is most clearly manifested. The first compiled Prodromus of vegetation of riparian forests of the Amudarya includes one class and order, two alliances and 5 associations. Poplar forests need to be protected which requires the creation of new bioreserves.