Fig. 1. Morphological features of Antirrhinum flowers: (left panels) wild-type; (middle panels) def; (right panels) def; AFI::DEF. (A-C) Photographs of whole mature flowers. The arrow in C indicates the shortened style of carpeloid third whorl organs (for comparison see the third whorl carpel in B). Bars, 5 mm. D-I: SEM micrographs of the inner (adaxial) epidermal surface of the upper (D-F) and the lower (G-I) regions of the second whorl organs. Bar, 20 µm. (J-L) Cross sections taken approximately in the middle of immature buds. Arrows in K and L point to the organ in the dorsal position in whorl 3, that is retarded in growth and is not visible in this section in wild-type (J) and transgenic flowers (L), but develops fully as a carpeloid organ in def mutant flowers (K). The flower in L, in contrast to the flower in C, did not develop a central carpel. Bar, 1 mm. (M-O) Cellular morphology of first- and second whorl organs in cross sections shown at a higher magnification. The shape and size of sub-epidermal cells in the transgenic second whorl organs in O is intermediate between the large and irregularly shaped sub-epidermal cells in whorl 2 of def mutants (N) and the small and more isometric sub-epidermal cells in wild-type petals (M). Bar, 100 µm. Numbers indicate whorls.