In Linum pubescens Banks & Solander and L. mucronatum Bertol. two floral morphs occur, differing in style length, stamen length, size of stigmatic papillae and, in L. mucronatum, exine sculpture of pollen grains. In both species artificial self- and intramorph cross-pollinations were incom, patible. Intermorph pollinations resulted in seed production. The inhibition of pollen-tube growth in incompatible pollinations occurs within the stigma. In L. pubescens distyly seems to be governed by a single pair of alleles. In natural populations the two morphs were found to be represented by approximately equal numbers of individuals. The effectiveness of the complementary arrangement of anthers and stigmas in promoting intermorph pollinations and in preventing pollen wastage in incompatible pollinations is discussed.