The cartoon to the right illustrates the stages of graft union formation.

  1. Lining up the vascular cambium of the scion and the rootstock and subsequent wound healing response.
  2. Callus bridge develops between scion and rootstock.
  3. Initiation of new xylem and phloem.
  4. Completion of vascular connection between scion and rootstock.

Illustration shwoing four stages of graft union formation. Photo showing a scion and rootstock being fitted together to form a graft.