关键词: 千金榆, 花器官, 小聚伞花序, 发育

Abstract: Morphogenesis of inflorescence and flowers in Carpinus cordata was observed under scanning electron microscope for the first time, which would provide micro-morphological evidence for the phylogeny and evolution in Betulaceae. The female inflorescence in C.cordata was composed of cymules arranged spirally; one primary bract and a group of cymule primordial meristem were differentiated from one cymule primordium, and two floral primordia and two secondary bracts were differentiated from the cymule primordial meristem; two carpel primordia were differentiated to form one bicarpellary pistil. The abaxial portion of secondary bracts developed faster than the adaxial one, which arranged in an unequal joint configuration. One layer circular perianth occurred in the base of pistil. The male inflorescences were catkin-like, composed of cymules arranged spirally. One primary bract and a group of cymule primordial meristem were differentiated from one cymule primordium, and three floral primordia were differentiated from the cymule primordial meristem, which differentiated into three small flowers without perianth, with two flowers laterally each having two stamens, and the small flower between them hasving four stamens. The total number of stamens of one cymule was eight, rarely ten. Three flowers are in a dichasial cyme, and the flower merosity is two.

Key words: Carpinus cordata, floral organs, cymule, development