We tested the hypothesis, suggested by literature data, that in Rumex obtusifolius L. the germination of matured seeds harvested from dry standing shoots and achene morphology are correlated. In these seed materials the level of germination is determined by the incidence of primary seed dormancy. The regression of the percentage of germinating seeds on achene, perianth and seed size and mass were calculated for seed materials of 30 plants. The materials in which achene morphology was investigated were selected ex post from a set of seed materials of 241 plants to cover the range of variation of germinability of individual plants which was between 0-66%. There was no relationship between any characteristic of achene quality and germination except for a positive correlation between germination percentage and achene mass calculated only for seed materials of plants which pro­ duced germinable seeds (i.e. when plants with 0% germination were excluded from the analysis). The second part of the study investigated the effects of size variation on germinability among seeds harvested from one plant and after removal from the perianth. This variation was tested using sets of 20 size-assorted groups of 50 seeds, each originating from a particular plant; materials from six plants were tested. There were significant differences in the average germination between plants. However, in the material from the same plant there was no consistent relationship between seed mass and percentage of germination. We conclude that there exists no direct relationship between achene, perianth or seed size or mass and incidence of primary seed dormancy.