Plant reproductive systems present a gradient of gender ranging from unisexuality to hermaphrodism. This variability in sex expression can be found within species and has been found to be influenced by external factors such as resource levels. The sexual strategy selected will depend not only on the number of pollen grains and seeds an individual can produce but also on the chance of success of this production. Production depends on trade-offs between female and male functions of hermaphrodites according to resource level and subsequent fate is influenced by selfing, inbreeding depression and competition among offspring. The goal of this study is to determine how interactions between these key parameters, resources availability, selfing and density-dependent competition within offspring influence the evolution of reproductive systems. We showed with a theoretical approach that (i) a change in resource level at the population level affects sexual strategies only in certain conditions; (ii) density-dependent seedling mortality disadvantages females compared to hermaphrodites and interacts strongly with resource level.