Symmetrical, referring to flowers: perianth symmetrical with respect to the axis of the flower. "Capable of being divided into equal halves along any diameter..." from the Free Dicti [..]

The flower shows radial symmetry and can be divided in half along many plains.

radially symmetrical on a single plane

Regular or radially symmetric flowers. actinotroch

of a flower with the parts in each whorl particularly sepals, petals and stamens not differing in shape, size or placement. The flower therefore can be bisected symmetrically in several planes. cf. zy [..]

[Symmetry] -- Of flowers, radially symmetrical; symmetrical about more than one plane passing through the axis of the flower, like a star.

(adj) capable of division into symmetrical halves by any longitudinal plane passing through the axis

<botany> Of flowers: symmetrical about more than one vertical plane. (09 Oct 1997)

Radially symmetrical; a shape that can be divided by 2 or more planes into roughly equal halves, usually refers to the perianth of a flower.