Vestigial corolla in flowers of birdsfoot trefoil

A naturally occurring floral mutant is infrequently observed in some popula tions of birdsfoot trefoil (Lotus corniculatus L). The petals of mutant flo wers are folded inward and do not extend fully, producing a vestigial corol la (vc), while other floral parts remain normal. The style extrudes through a gap between the rudimentary keel and the folded standard, Consequently, the stigma and style extend beyond the corolla and are exposed, The spatial separation between stigma and anthers could facilitate hand-pollination as it eliminates the need for emasculation. The objective of this study was t o determine the fertility oft. corniculatus genotypes expressing sc floral characters. Sixteen genotypes of L. corniculatus expressing the re phenotyp e were collected from field grown populations. Pollen from vc genotypes was compared with pollen from genotypes of the germplasm MU-81 used as control s. All vc genotypes produced some pollen that appeared normal, although the quantity of such pollen was variable among the vc genotypes. Mean pollen g ermination among sc genotypes was 22%, compared with 50% for MU-81. Only fi ve of 16 vc genotypes produced pods when crossed to genotypes of MU-81 and both pod and seed set were less than in control crosses. Normal and abnorma l ovules were observed in ovaries of vc genotypes and the reduced fertility may have resulted from smaller, incompletely developed ovules. Unidirectio nal reversion of the vc genotypes, from abnormal to normal flower morpholog y, was common. Using the vc mutant to eliminate the need for emasculation i n hand-pollination programs depends on its fertility. The combination of ph enotypic instability and reduced fertility make the vc mutant less desirabl e for use in breeding programs.