Corrigiola litoralis L. is mostly claimed to specialize its habitat in W.- en C.-Europe on river shores and banks consisting of course sand and gravel with fluctuating water level. Moreover, this habitat should be restricted to a nitratophilous one; its vegetation belongs to the Chenopodion fluviatile (Bidentetalia). However, this habitat appears to be only one of four main habitat types; it occurs in W.-Germany, N.-France and locally in S.-England. A second habitat type is the slightly ruderal “off the road-locomotion-gradient” along tracks and paths on damp sandy or loamy heath and moorland soil (Spergulario-Illecebretum, Nanocyperion); it is known from the Netherlands and N.-Belgium. The attention in this paper is focussed to a third, apparently very different habitat type: the ecosystem of dry railway tracks, strongly ruderal and consisting of gravel and coarse sand. It has been observed in many localities in the Netherlands and it is also known from England, Belgium, Denmark and W.-Germany. The fourth ecosystem group consists of ephemeral disturbance communities on sand pits, round about rabbit holes, on burnt moorland etc.; it is intermediate between the second and the third one. The railway track ballast habitat and the river shore gravel one are corresponding in two respects: their “permanent pioneer” character and the coarse texture of the very permeable substrate with its high air content. By these conditions the water regime of the habitat is apparently irrelevant, these environments varying from wet to very dry. Only in the case of the second habitat type the """"off the road-locomotion-gradient"""" along tracks on sandy moorland the moisture content of the soil is indispensable.