The concept was rejected that in the Mediterranean and Euro-Siberian regions the class Rudereto-Secalinetea would consist of vicarious orders or alliances. The following views were presented:The characteristic species of this class are indigenous and foreign adventive weeds. Its associations are made up of colonists. Most end their cycle within a year by natural succession (the indigenous associations) or by human influences (almost all adventive ones).Because all these associations are adventive, nitrophilous, anthropogenous weed communities, they can be called domestic associations.Four orders can be distinguished in the Netherlands. The Secalinetalia and the Chenopodietalia (formerly considered as one order) cover associations on regularly cropped soils tilled at least once a year. The Secalinetalia overwinter on most fields with autumn and early spring sown field crops; the Chenopodietalia occur in weeded crops. The Potentillo-Polygonetalia cover associations of rosette and tread plants on compacted substrates. The Onopordetalia occur on muck heaps, refuse and verges with nitrogen-rich substrates.The floristic composition and the growth conditions of all associations were discussed at length.
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