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Botany · Ch 4 — Reproductive Morphology

Flower symmetry

4.2.4

Flower symmetry

Flower symmetry describes how many planes drawn through the centre of a flower will divide it into two identical, mirror-image halves - an important structural adaptation tied to how the flower is pollinated. An actinomorphic (radial, polysymmetric) flower can be cut into two identical halves along more than one plane through its centre (Hibiscus, Datura, water lily). A zygomorphic (bilaterally symmetric, monosymmetric) flower can be divided into equal halves along only one specific plane; this shape lets the flower guide a visiting pollinator's body more precisely, transferring pollen more efficiently (Pisum, bean, Cassia, gulmohar, Salvia, Ocimum). An asymmetric (amorphic …

Figure 4.13Actinomorphic, Zygomorphic and Asymmetric flowers

What this figure shows. (a) An actinomorphic (radial) flower, such as Hibiscus, shown with several dashed lines radiating through its centre, each dividing it into identical mirror-image halves. (b) A zygomorphic (bilateral) flower, such as Pisum/pea, shown with only one dashed line through its centre producing equal halves. (c) An asymmetric flower, such as Canna indica, shown with its parts irregularly twisted so no dividing line pro …