De Tengere distel (Carduus tenuiflorus Curtis) op Wieringen

Since 1950, Carduus tenuiflorus has been reported from three different locations in the coastal areas of the Netherlands. At present the species is only extant on the island of Wieringen (province of Noord-Holland), a former island consisting of a moraine of Pleistocene age, now surrounded by polders. Here, the species grows in soil rich in nutrients, on a dike constructed in the period 1594— 1624. In 1993 some tens of plants were found growing near this spot, in a meadow used to graze sheep. However, a survey over the island of Wieringen revealed two new localities. A single plant was found growing in a grassy roadside at a distance of a few hundreds of meters from the known locality, and some tens of plants were found in a roadside with ruderal vegetation at about 5 kms from the known locality.