Potamogeton coloratus Hornem. has not been found in the Netherlands for more than 130 years, and was recorded from only two localities in the western part of the country. In 1978 the species was discovered on mud in a newly dug ditch in the dunes of the isle of Texel. From an investigation in the Rijksherbarium at Leiden it turned out, that already in 1867 a specimen of P. coloratus was collected at the same place.