Abstract: It is shown anatomical that there is a cotyledon node zone(CNZ) in the seedling of Delphinium grandiflorum. And there are two transitional regions in the CNZ of D.grandiflorum, namely, cotyledon node stem, transitional region upwards and cotyledon node root transitional region downwards. The primitive exarch and diarch haplostele with cross-like metaxylem exists in the lower part of CNZ. This provides a new information for revealing further the origination and evolution of species of Ranunculaceae.

Key words: Delphinium grandiflorum, Cotyledon node zone, Primary vascular system, Cross-like haplostele