POLYAXIAL DEVELOPMENT IN HOMEOTIC FLOWERS OF 3 BEGONIA CULTIVARS

Development of staminate flowers in double-flowering Begonia semperflo rens-cultorum cultivars 'Cinderella', 'Goldie Locks', and 'Lucy Locket t' was examined using epi-illumination microscopy, focussing on later stages when secondary partial floral buds formed on the floral apex. T his process, switching from floral to inflorescence-like development, is an example of homeosis, the expression of inflorescence features on a floral apex. Floral development began as in a normal begonia flower with the formation of a perianth consisting of two sepals and two pet als, but sepaloid and (or) petaloid appendages then developed in what corresponded to stamen positions in normal Begonia species. This was u sually followed by lateral elongation, distortion of the primary flora l apex, and formation of secondary partial floral buds. The pattern of primordial inception on the secondary apices tended to be irregular, but in some cases, appendage primordia formed in groups of twos, three s, and fours, and in a somewhat alternating formation on the apices. O ften, primordial initiation seemed to continue on secondary apices eve n after anthesis of the staminate flower. Appendage primordia that for med on the secondary buds usually were laterally elongate and bifacial , giving them a phyllomic appearance. Others were, on occasion, more h emispherical at inception, but as they developed they became phyllomic .