The flowers are always more or less bilaterally symmetrical (zygomorphic).
When a flower can be divided by a single plane into two exactly similar parts; then it is said to be zygomorphic.
In Pelargonium the flower is zygomorphic with a spurred posterior sepal and the petals differing in size or shape.
zygomorphic zy·go·mor·phic (zī'gə-môr'fĭk, zĭg'ə-) or zy·go·mor·phous (-fəs)
Bilaterally symmetrical. Used of organisms or parts.
Relating to a flower that can be divided into equal halves along only one line; bilaterally symmetrical. The flowers of the iris and the snapdragon are zygomorphic. Compare actinomorphic.