Abstract: Aquilegia oxysepala belongs to Ranunculaceae. Studies on the primaryvascular system of the seedling showed that A. oxysepala was the same as. other genera of the Ranunculaceae in that there were two transition regi-ons with the cotyledon node zone (CNZ) being the centre. The primaryvascular system of the seedling could be divided into the three parts:epi-cotyl shoot zone, cotyledon node zone and hypocotyl root zone. The resultsfurther verified that the cotyledon node zone proposed by Gu An-gen (1990)did exist, and also provided a new materal for the studies on the originand evolution of Ranunculaoeae.

Key words: Aquilegia oxysepala, Seedling, Primary vascular syetem