The perianth of Calceolariaceae is shown to be derived from a tetramerous condition, not from pentamery as traditionally believed. |
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The other viewpoint is that the number of rays is intrinsically fixed at five, and therefore it is the deviations from pentamery that need explanation wherever they occur. |
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Evolution of dimery, pentamery and the monocarpellary condition in the monocot family Stemonaceae. |
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