The mating systems of species in small or fragmented populations impact upon their persistence. A recent study published in AoB PLANTS by Silva et al. highlights the value of performing detailed mating system studies in plant species of high conservation value, such as the rare and relict species of Sonchus section Pustulati. The study adds to the evidence that outcrossing mating systems based on sporophytic self-incompatibility are highly resilient even under long-term conditions of small, fragmented, and isolated populations. This is possibly due to mating system flexibility with the presence of some selfing and the fact that high cross-compatibility is achieved for relatively modest dominantly expressed S allele polymorphism. The authors highlight the importance of taking mating system factors into account as part of conservation efforts.