Germinability and seedling size of seeds from hermaphrodite and female plants of the gynodioecious and gynomonoecious taxon, Silene vulgaris (Moench) Garcke, were compared to address one aspect of life history which may maintain two types of breeding individuals in the same population. Two hundred seeds were randomly selected, 10 from each of 20 different maternal parents in the field, hermaphroditic and female, and germinated on moist filter paper at 20 C, 16 h day/8 h night photoperiod. After two weeks, the radicle length, and cotyledon length, width and area of a total of 200 seedlings from 11 hermaphroditic and 16 female parents were compared. There was no statistically significant difference in the average mass of seeds which produced seedlings (0.8997 mg +/- 0.0392 vs. 0.9752 mg +/- 0.2400, hermaphrodite and female, respectively). The seedlings from the two types of parents did differ, however, in cotyledon and root size. Seedlings from hermaphrodites had significantly longer radicles and smaller cotyledons on the average than those of females (25.4 mm +/- 1.81 vs. 19.8 mm +/- 1.93 and 7.06 mm2 +/- 0.305 vs. 13.3 mm2 +/- 0.536). These different growth responses of the seedlings may promote differential survival, particularly in certain microsites. These data are considered in light of earlier work on the relative success of inbred and outcrossed progeny in the field.