Regeneration of Vascular Tissues in Broussonetia Papyrifera Stems After Removal of the Xylem

The central cylinder of xylem plus pith was removed from the main stem of 1- to 2- year-old Broussonetia papyrifera (L.) Vent. treelets, leaving only the bark, cambial zone cells and a few immature xylem cells. The immature phloem and xylem cells and original cambium zone cells rapidly produced callus, then the original cambial zone started to produce xylem and phloem. A flat meristem was initiated intermittently inside the callus. Eventually, these islands connected laterally to form a ring of new cambium that began to produce normal xylem inward and phloem outward. About one month later, a concave oblate trunk had formed, which connected distally and proximally with the original trunk.