Stamen division

Rose and Carnation. The doubling of flowers is brought about through cultivation and is due either to the transformation of stamens (as in cases cited), and occasionally of carpels into petals, to a division of the petals, or to the formation of a new series of petals. 

S. Ichikawa and A. H. Sparrow, The use of induced somatic mutations to study cell division rates in irradiated stamen hairs of Tradescantia virginiana L., Japan. 

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