Over de Nederlandse lijst van hydro-, freato- en afreatofyten

List of hydro-, phreato- and aphreatophytes in the Netherlands Phreatophytes are species (or other taxa) which are in a certain part of their distribution area exclusively or mainly limited to the sphere of influence of the phreatic surface (level of the ground water). Species which in their distribution are not limited to this sphere of influence, are called aphreatophytes. A list (LONDO, 1975) was made on the basis of field observations for the purpose of ground water management in the Netherlands. The following categories are distinguished: H—Hydrophytes, species with vegetative parts submerged and/or floating on the water surface. W—Species requiring for at least part of the year a (ground) water level above or at the soil surface (in years with a normal water table) for a good development and completion of their life cycle (e.g. germination). F—Species growing exclusively within the sphere of influence of the phreatic surface, which is generally below the soil surface. Species of categories W and F are strictly phreatophytes. f—Species growing mainly or nearly exclusively within the sphere of influence of the phreatic surface, which is generally below the soil surface. The species of this category as well as those of the following categories (f) and a, are not strictly phreatophytes. (f)—Species growing in the greater part of their area in the Netherlands within the sphere of influence of the phreatic surface (which is generally below the soil surface), but also occurring, and often abundantly in certain habitats (especially in areas rich in lime), above this sphere of influence, a—Species which in many habitats in the Netherlands are not limited to the sphere of influence of the phreatic surface (here they are aphreatophytes), but which grow exclusively or mainly within this sphere of influence, locally especially in dunes or other sandy areas. A—Species not bound to the sphere of influence of the phreatic surface (aphreatophytes). z—Species growing only in salt habitats. Species of salt habitats occurring (sometimes incidentally) also in environments with fresh ground water, are classified in one of the other categories. Underlining in the list of H, W, F, f, (f), and a means that the concerning species are characteristic for the relatively constant (less dynamic), and/or relatively oligotrophic, and/or vulnerable habitats, or that (relatively) rare species of more dynamic and/or eutrophic habitats are concerned. On the basis of a floristic survey of an area, and with the help of this list one can determine the vulnerability with respect to changes in the (ground) water table and changes in the chemical composition of the water.