A phyllome (PO:0006001) that is part of a perianth (PO:0009058) where it is not possible to distinguish between the petals (PO:0009032) and sepals (PO:0009031). [source: POC:curators]
Comment
There is no differentiation between the petals (PO:0009032) and the sepals (PO:0009031) in color, placement, and size (e.g. some species of Magnolia).