Korstmossen en mossen op dijken en iepen bij Hoorn (Noord-Holland)

The dykes and Ulmus trees along the IJsselmeer near Hoorn (Prov. Noord-Holland) proved relatively rich in lichen species. The only rare species found on Ulmus was Singula affinis. The following three species, Bacidia viridifarinosa, Caloplaca britannica, and Leptogium teretiusculum are reported for the first time from the Netherlands. The Caloplaca was found on exposed granite, the Bacidia and the Leptogium on sheltered brick between granite boulders of the dyke. Also some hygrophytic mosses are present, including Rhynchostegiella jacquinii.