Generally, this means the flower has a rotational symmetry. This produces flowers with an over-all shape which is round, tubular, urn, or bell like.
Generally, this means the flower has a mirror symmetry (or no obvious symmetry at all.) Again, this applies to the individual flower, not the inflorescence (that is, not the flower cluster). For example, the first two plants shown below, the Plantain and the Clover, have an inflorescence that is simply shaped, but the tiny individual flowers are odd.
