Parnassia palustris L. in Zuid-Limburg

In the early part of this century, Parnassia pa lust r is was found in at least 59 localities in the southern part of the Dutch province of Limburg. Although, descriptions of these habitats are scarce, three main types could be distinguished: spring bogs, upper part of slopes in the transitional zone between chalk and gravel deposits, and wet haylands along brooks. Phytosociological data are discussed in detail. Between the two World Wars, the number of sites decreased enormously due to changed agricultural activities, especially the use of artificial fertilizers and drainage of wetlands. Today, only two localities remain. One, in a spring bog, is threatened by road planning. At the other locality, the upper part of a slope covered with species rich grassland, influx of fertilizers from an adjacent, uphill situated arable field is a serious threat.