Naarden-Vesting vanaf het ijs gezien

The fortifications of Naarden-Vesting provide some of the best habitats for saxicolous lichens in the Netherlands. Most of the suitable walls are perpendicular, bordering on deep water. The frost period in December 1995 provided a good opportunity to visit areas which could not be reached during a previous excursion (see Buxbaumiella 35: 48-57, 1994). No less than two species, viz. Leptogium turgidum (which was growing side by side with L. schraderi without transitions) and Verrucaria caerulea, were found here for the first time in the Netherlands. It is also nearly the only known locality in the Netherlands of Collema fuscovirens (which is still abundantly present) and of Mycobilimbia lobulata (which could not be found recently).