1. Norwegian Institute of Land Inventory, P.O. Box 115, N‐1430 Ås, Norway
2. Department of Biology, Division of Botany and Plant Physiology, University of Oslo, P.O. Box 1045, Blindern, N¡0316 Oslo, Norway
3. Botanical Museum, Univ. of Oslo, P.O. Box 1172 Blindern., N‐0318 Oslo, Norway