Inflorescence And Flower Development Of Celastrus And Euonymus (Celastraceae)

Because of difficult sampling, very small flower and the long development cycle, the research of inflorescence and flower development of Celastraceae was still in blank. The inflorescence and flower of four species of Celastrus and Euonymus were studied with anatomical observation, paraffin section and scanning electron microscopy (SEM). Architecture of dichasial cyme and developmental process of inflorescence and flower were described, enriching the floral organ development theory of Celastraceae; combined with the observed phenomena and other data, we attemptd to discuss the relationship between single flower and inflorescence, evolutionary relationship of different inflorescences types in Celastraceae. The main results were as follows:1. the developmental process of dichasial cyme in Celastrus and Euonymus was divided into3(4) phases:basic structure formation phase, Pedicel and Peduncle elongation phase,(bract abscission phase), inflorescence structure simplification phase. In Basic structure formation phase, the development followed the sequence from the lower to the higher structure.2. There was some morphological variation in all the developmental phases of dichasial cyme, and that was why dichasial cymes of Celastraceae had large differences in different species, even in the same plant.3. The morphological differentiation of flower was divided into5phases:flower primordial differentiation phase, sepal differentiation phase, petal differentiation phase, stamen differentiation phase and pistil differentiation phase.4. In Euonymus and Celastrus, a single flower is a simple form of a inflorescence. Single flower and inflorescence could not be distinguished clearly, considering the developmental process of inflorescence and the phenomenon of flower abortion.5. In Celastraceae, the evolution of inflorescence might show the following trend:dichasial cyme was the most fundamental inflorescence type, and the other inflorescence types could be evolved from it.6. The articulation was a special structure of Celastraceae. In morphology, the articulation was the boundary marker btewwen Peduncle and pedicel, and the part above articulation was the true pedicel of flower. In function, the articulation was related with flower falling.