This association is formed of herbaceous stands dominated by species of the genus Aster of North American origin, namely A. lanceolatus and A. novi-belgii. They occur on ruderal sites in human settlements, e.g. on building rubble, dumping sites, along fences, on roadsides or in unmown grasslands. Often they are found in fringes of floodplain forests and on banks of streams and shores of fishponds. Relevés with invasive Aster species are available mainly from southern Moravia, although this vegetation type occurs in other areas of the Czech Republic as well.