Vorkommen der Kleinen Teichrose Nuphar pumila und des Hybrids N. x intermedia in der Schweiz

Abstract.

Kozlowski G. and Eggenberg S. 2005. Distribution of the least water-lily (Nuphar pumila) and the hybrid N. x intermedia in Switzerland. Bot. Helv. 115: 125–136.

The least water-lily (N. pumila (TIMM.) 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 N. pumila 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 N. lutea. In these two lakes, the hybrid N. x intermedia was very abundant. The presence of N. lutea and N. intermedia in Kämmoosteich and Lac de Lussy should be regarded as one of the most serious threats of pure N. pumila 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, N. pumila 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.