ABSTRACT
INTRODUCTION BROADLEAVED TREES AND CONIFERS In conifers and broadleaved trees undergoing woody thickening (274), new (secondary) conducting vascular tissues are generated from a specialized hollow cylinder of tissue, termed the vascular cambium (275). Secondary wood (xylem) is formed to the inside of the cambium, while phloem (inner bast) is developed on the outside (276D, 277D). Nearly all of the increasing girth of such a tree is due to its expanding core of wood, which provides both water conduction and mechanical support.
