Organization, available space and organ morphology within floral buds of Iris (Iridaceae)

•Floral packing geometries differ among species even when morphologies are similar.•The “filling law” proposed for vegetative buds does not apply to floral buds in Iris.•The petaloid style branch in Iris develops in the space where the missing second stamen whorl would occur.•Stamens show considerable flexibility in shape, size, and organization within the floral bud of Iris.•We hypothesize that there is coordination of growth among floral whorls within the bud.