1. Optimisation models 2. Investments, returns and proportionality 3. Gain curves: efficiency factors 4. Evolutionary stable strategies: sex allocation strategies as an example 5. Size at flowering 6. Reproductive effort 7. Size and number trade-offs: the evolution of seed size 8. Sex allocation theory for partially selfing plants 9. Size dependent sex allocation 10. Sex ratios in dioecious plants 11. Outcrossing, selfing or no sex at all? 12. Heterostyly 13. Selective embryo abortion 14. Attractiveness to pollinators 15. Parent-offspring conflict 16. Intragenomic conflict 17. Group and kin selection Appendix 1. Mathematical help References.