Other than cataclysm, asymmetrical attack, or government gone wild, we have little to worry about.
Usually this aperture is median, but occasionally asymmetrical.
Thus in the horse-chestnut there is an interposition of two stamens, and thus seven stamens are formed in the flower, which is asymmetrical.
Asymmetrical, inequivalve, fixed, with extensive pallial sutures; no siphons.
Branching of stamens also produces apparent want of symmetry; thus, in the so-called polyadelphous stamens of Hypericaceae there are really only five stamens which give off numerous branches, but the basal portion remaining short, the branches have the appearance of separate stamens, and the flower thus seems asymmetrical.