Zygomorphic
Zygomorphic or bilateral (or irregular) - also known as monosymmetric.
- divided into equal halves along one (longitudinal) plane only, or in other words,
- divisible through the centre of the flower in only one longitudinal plane for the halves of the flower to be mirror images.
Illustration from Clarke, I. & Lee, H. (2003) Name that Flower, Melbourne University Press, Victoria.