Kozlowski, Gregor Eggenberg, Stefan 2005 The least water-lily (<i>N. pumila</i> (<small>TIMM</small>.) DC) is very rare and endangered in Switzerland and Central Europe. To provide a basis for its conservation, we present a distribution map with all natural, re-introduced and extinct populations in Switzerland. Only four natural populations of <i>N. pumila</i> still exist in Switzerland: Lac de Lussy and Lac des Joncs (FR), Gräppelensee (SG), and Kämmoosteich (ZH). These populations and their sites (lakes) are described, and the co-occurring plant species are listed. Results suggest that the populations from Kämmoosteich and Lac de Lussy are affected by hybridisation and competition with <i>N. lutea</i>. In these two lakes, the hybrid <i>N</i>. x <i>intermedia</i> was very abundant. The presence of <i>N. lutea</i> and <i>N. intermedia</i> in Kämmoosteich and Lac de Lussy should be regarded as one of the most serious threats of pure <i>N. pumila</i> populations. To facilitate further investigation and conservation field work, a detailed morphological description of the two taxons is presented and illustrated by original drawings. To escape extinction in Switzerland, <i>N. pumila</i> needs further appropriate action plans for all natural and newly re-introduced sites as well as an improved knowledge of its genetic structure and habitat preferences. application/pdf https://folia.unifr.ch/global/documents/299904 https://folia.unifr.ch/documents/299904/files/1_kozlowski_vkt.pdf ger info:eu-repo/semantics/altIdentifier/doi/10.1007/s00035-005-0709-8 info:eu-repo/semantics/openAccess License undefined Botanica Helvetica. - 2005, vol. 115, no. 2, p. 125-136 conservation biology distribution map endangered plant species hybridisation Nupharetum pumili Nympheaceae info:eu-repo/classification/udc/57 Vorkommen der Kleinen Teichrose Nuphar pumila und des Hybrids N. x intermedia in der Schweiz http://purl.org/coar/resource_type/c_6501