Consequently, in central populations, the HE value of late-opening flowers decreased from 1.65 to 1.45 mm in the S-morph and from 1.53 to 1.27 mm in the L-morph, but the RHE value showed no significant decline in the S-morph ( P > 0.05) and only a marginally significant decrease in the L-morph ( P = 0.011).
Highly significant correlations were detected between CTL and the positions of sexual organs in both morphs ( Supplementary Table 5 ), as documented in other distylous Primula species, suggesting that corolla tube elongation plays an important role in the spatial arrangement of sexual organs in the Primula genus ( Kálmán et al., 2007 ; Zhu et al., 2009 ; Keller et al., 2012 ; Brys and Jacquemyn, 2015 ).