The paper characterizes poplar (Populus alba, P. nigra) and white willow (Salix alba) forests of the Irtysh and the Black Irtysh river floodplain, together with the silvery salt tree (Halimodendron halodendron) community of the Black Irtysh river floodplain. The Black Irtysh floodplain willow and poplar forests are separated into a new alliance, Rubio dolichophyllae—Populion albae Taran all. nov. (Salicetalia purpureae Moor 1958, Salicetea purpureae Moor 1958), which includes the associations Rubio dolichophyllae—Populetum albae Taran 1997 and Rubio dolichophyllae—Salicetum albae Taran ass. nov. The Halimodendron halodendron community is probably related to the class Nerio-Tamaricetea Br.-Bl. et de Bolós 1958. White poplar forests in the Irtysh R. upper reaches, described within the Semipalatinsk city limits, belong to the association Heracleo dissecti—Populetum albae Taran 1997 and its subassociation H. d. —P. a. lamietosum albi Taran 1997 (Equiseto hyemalis—Populion nigrae Taran 1997, Salicetalia purpureae Moor 1958).