Small, locally dominant plants of Juncus effusus f. pauciflorus have been collected in the exceptionally warm and dry summer of 1976 on the dry bottom of a wide ditch in the Southwestern part of the country near Roosendaal (prov. of N.-Brabant). Earlier such forms were known in the Netherlands from four localities. All the summers of the years in which these forms had been found were characterised metereologically as „(very) hot” as well as „(very) dry”, which is very unusual in this country. The individual plants have normal terete stems, sometimes with young ‘lateral’ inflorescences, as well as small, filiform stems bearing apicallya few fruits and with the lower sheaths terminating in distinct linear blades; fruits of the latter are usually not retuse at the apex, and contain apparently normal seeds ( fig. 1). Ontogenetical research on the unusual dimorphism of this form is required.