Symmetry of the Flower

When you look at a flower, it normally will exhibit one of two aspects.  Many will be such that you could form a mental image of sectioning the flower down the middle, and no matter how many times you do that you would get a mirror image.  This is radial symmetry.  Other flowers show an aspect where, after a mental section, you get only one mirror image.  That is bilateral symmetry. 

The way it works with the plant kingdom is as follows:  actinomorphic (regular) flowers show radial symmetry.  The petals are of the same size, color and shape.  Zygomorphic (irregular) flowers show bilateral symmetry.  Their petals are probably going to differ in shape, size and color.  Examples are below. 


Regular Irregular

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In this ornamental phlox, you see five petals all the same size and color.  You can section out five mirror images.

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The flower of the Fabaceae family is highly irrigular.  Even in black and white it is obvious that there is only one mirror image possible after sectioning.
bloodrootflower.jpg (23922 bytes) You can section out numerous mirror images in the bloodroot flower.  The petals are all the same shape and size.

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This member of the mint family has sympetalous flowers, but you can see how different the petals are in that tube in terms of shape and size.

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This clematis can be sectioned six times and always show a mirror image.

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This bellflower is slightly irregular.  Petals are of the same color, but not of the same size.