New association of weed vegetation in the Southern Ural

A geobotanic survey was carried out and the diversity of weed communities of the steppe zone of the Orenburg and Ilek administrative Districts of the Orenburg Region was revealed. As a result of the synthaxonomic analysis, the studied communities are assigned to the new associationAmarantho blitoidis-Lactucetum tataricaeass. nov. hoc loco in the system of units of ecological-floristic classification of Eurasia vegetation. The association united weed communities of spring wheat, sunflower, less often rye, barley, corn and sorghum, emerging mainly on well-drained swollen soils in the flood of the Ural River. The cenophlora is characterized by the presence of bondate and optional psammophytes Chondrilla brevirostris,Helichrysum arenarium,Ceratocarpus arenarius, etc. The communities of the association occupy an extreme position on gradients of aridity and moisturization factors among other weed vegetation communities of the Southern Ural. The North American alien speciesEuphorbia glyptospermaEngelm has been discovered for the first time in the Orenburg Region (subgenusChamaesyceRaf., sectionAnisophyllumRoep.). Currently this species is expanding its range from the south of the Russian Federation. Other alien plants have been noted as part of the communities:Amaranthus blitoidesS.Wats.,A.retroflexusL.,Conyza canadensis(L.) Cronq.,Xanthium album(Widder) Scholz et Sucopp.