Carex. x tornabenii (C. distans x extensa) was recorded for the first time in the Netherlands, on the island of Texel, in 1985. The single specimen grows between the parents in a nature reserve in the dunes in which North Sea water freely goes in and out. In that area, formerly saline or brackish, recently a rather strong influence of sweet seepage water has been observed; this environmental change may have favoured the occurrence of the hybrid. It is remarked that the flowering period of C. distans and C. extensa shows a greater overlap than usually assumed.