Development and Histochemistry of the Secretory Canals in Bupleurum chinense

Distribution,development and histochemistry of secretory canals in roots,stems and leaves of Bupleurum chinense were studied,by using plant anatomy and histochemical methods.The secretory canals were distributed in the pericycle and secondary phloem of root,in the phloem and pith of stem,and in the phloem and above xylem of the vein in leaf.The secretory canal in root pericycle was developed from a group of pericycle cells.The secretory canals in root secondary phloem initiated from the outer derivative cells of the vascular cambium.The secretory canals presenting in phloem of stem and leaf originated from two or three exterior layers of protophloem cells in the procambium bundles.The secretory canals in the stem pith and above the leaf xylem were developed from ground meristem.The lumens of these secretory canals were formed by cell wall separation,i.e.,schizogenous.Histochemical tests showed that these secretory canals contained essential oils and were also important distribution sites.