Het voorkomen van Haarfonteinkruid (Potamogeton trichoides Cham. ex Schld.) op het Plistoceen van Zuid-Nederland

During the last two decades Potamogeton trichoides has increased considerably in the southern part of the Netherlands, on Pleistocene subsoils, in the middle and lower stretches of lowland streams and drains. It grows in eutrophic, neutral to alkaline water partly let in from large rivers, that is polluted by agriculture as well as by sewage purification installations. The streambed usally consists of sandy soil, often covered with thin sapropelium. Elsewhere in the Netherlands the species is usually found in less eutrophic environments, in polder ditches with stagnant water on clayey or loamy soil. It is often found on places with seepage water. Elsewhere, the species has been observed in streams in Belgium, Germany and in Hungary. Plants in flowing water may reach a length of 1.5 m, twice the length of plants in stagnant water. It is suggested that in flowing water the species may occur in more eutrophic conditions than in stagnant water.