Abstract:Somatic chromosomes of root tip cells in the seedlings of dioecious Cunninghamia lanceolata were studied with Giemsa C-banding technique. The metaphase chromosomes had two heavy C-bands in the secondary constriction and terminal satellite regions of the one pair of homologous chromosome. It was found that some seeds exhibited this pair of C-bands in different size, while some other seeds exhibited this pair of C-bands in same size. The corresponding results can also be observed in their interphase chromosomes. Based on these results, it was conjectured that the sex differentiation may exist in the seeds of dioecious Cunninglamia lanceolata and the transformation of sex expression may occur in the development process of this plant.