Commented phytosociological relevés from the Czech Republic. 1.

This paper is the first set of a series of publications commenting on remarkable phytosociological relevés from the Czech Republic. It deaks with the following five vegetation types: (1) Calcareous Pinus sylvestris woodlands growing on limestone outcrops in the Moravian Karst and probably belonging to the Erico-Pinion alliance, comprising peri-alpidic calcareous pine forests, a vegetation type which is very rare in the Czech Republic. (2) Rare ruderal vegetation with a high cover of Chenopodium murale (Polygono arenastri-Chenopodietum muralis association) was recorded in south Moravia. (3) A ruderal community dominated by Tribulus terrestris and classified as the Tribulo terrestris-Tragetum racemosi association, was recorded in the city of Brno for the first time in the country. (4) Halophilous grassland of the Puccinellietum limosae association was recorded at a restored saline site named Zápověď near Terezín in south Moravia. (5) Species-poor vegetation dominated by the alien aquatic fern Azolla filiculoides, classified as the Ceratophyllo-Azolletum filiculoidis association, was recorded in Moravia for the first time.