Flowering plants display an extensive range of adaptive floral forms, which are often correlated with their mating systems. The maintenance of contrasting strategies such as those adopted by obligate outcrossers compared to populations that have evolved a selfing system is one of the most studied topics in reproductive evolution.
Voillemot and Pannell study variation in mating systems in Spanish toadflax Linaria cavanillesii, a long-lived perennial species. Some unexpected features are reported, such as an absence of shift in flower morphology in the self-compatible population, together with the maintenance of outcrossing despite no apparent inbreeding depression.
Voillemot, M., & Pannell, J. R. (2016). Maintenance of mixed mating after the loss of self-incompatibility in a long-lived perennial herb. Annals of Botany, 119(1), 177–190. https://doi.org/10.1093/aob/mcw203