radial symmetry

The arrangement of parts in an organ or organism such that any cut taken through the centre divides the structure into similar halves. Most stems and roots exhibit such symmetry. Radial symmetry in flowers is usually termed actinomorphy. The flowers of relatively primitive angiosperm families, e.g. Ranunculaceae, are usually actinomorphic. In a floral formula, actinomorphy is represented by the symbol .