Testing sex-allocation theory: flowers vs seeds in hermaphrodite plants

Plants of the self-compatible Echium vulgare and Cynoglossum officinale fre quently abort seeds, while all flowers contain pollen. Sex allocation then changes with the seed to flower ratio. Based on our field data, we can draw fitness sets. The analysis shows, that the fitness set is bowed out and th at hermaphroditism is evolutionarily stable in both species. It also predic ts correctly the size-dependent pattern of seeds per flower observed in C. officinale in the field, where small plants produce 0.39 and large plants 0 .85 seeds per flower. The model fails to predict the pattern in E. vulgare.