Large samples of mature flower buds of Ranunculus repens L., from three different positions on the inflorescence, were collected at two localities near London during the early summer of 1959. From each of the six collections 320 normal flower buds were dissected, 160 with a right quincuncial calyx and 160 with a left quincuncial calyx, and the aestivation of the corollas recorded.

Although the corolla aestivation is very variable and all thirty-two possible arrangements are found in each sample the petal overlaps are not randomly distributed and can be related to the two calyx types. The analysis provides evidence that the aestivation pattern differs with position of the flowers on the inflorescence and that for samples of flowers from any one position on the inflorescence the pattern is similar from site to site and from year to year.

Comparison is made with other published work on variable, imbricate pentamerous corollas and the significance of the observations is briefly discussed.