Figure 3.

Parental and F1 phenology: Flowering phenology of Primula elatior (EL^♀ × EL^♂), Primula vulgaris (VU^♀ × VU^♂), and their F1 hybrids (EL^♀ × VU^♂ and VU^♀ × EL^♂) recorded weekly from plants in a common‐garden experiment, with means (circles) and standard deviations of onset (i.e., date of first flower opening; black symbols), peak (i.e., date of maximal number of open flowers; white symbols), and end (i.e., date of last flower wilting; dark gray symbols) of flowering times. Percentages of total numbers of open flowers per census day (bars) are reported on the y‐axis for a total of 10 census days (x‐axis); 601 flowers in 20 plants of P. elatior, 852 flowers in 22 plants of P. vulgaris, 1287 flowers in 17 plants of EL^♀ × VU^♂ hybrids and 441 flowers in 15 plants of VU^♀ × EL^♂ hybrids were surveyed during their entire blooming period. Census data were used to calculate phenological isolation (RI_phenoP) and F1 phenology (RI_phenoF1; see text).