Fig. 3.

Age of divergence (Wikström et al., 2001; MYBP = millions of years before present) of families categorized as having self-compatibility (SC), heteromorphic, or one of the following SS/SI phenotypes: stigmatic, stylar, or ovarian SI, post-fertilization SS, Heteromorphic + SI (Het + SI) and SS unclassified. When polymorphic expression of SS/SI (two or more sites of pollen tube inhibition have been noted in the same family), the age of divergence of the family was plotted multiple times to heuristically visualize the time of appearance of the SS/SI phenotype.