The potential for mixed mating in a self-incompatible plant

A previous study showed that flowers of Campanula rapunculoides (Campanulac eae) are strongly self-incompatible when the stigma first becomes receptive but are less strongly self-incompatible as the flowers age. We deposited e quivalent loads of self and outcross pollen onto either 1-d-old or 4-d-old stigmas and examined seed paternity using the PGI (phospho-gluco-isomerase) genetic locus. Pollen mixtures (50 : 50) on young flowers yielded only out cross progeny, indicating functional self-incompatibility. Pollinations on the older stigmas, however, resulted in progeny arrays that departed signif icantly ( chi (2) test, from the P < 0.001) expectations from pure outcross sing, with self-fertilizations estimated at 15%-22%, depending on the cross . The ability to produce both selfed and outcrossed progeny, i.e., mixed ma ting, coupled with a 6% increase in fruiting success of C. rapunculoides fl owers pollinated shortly before floral senescence may provide an opportunit y for reproductive assurance in natural populations of this species.