|xylem (ˈzaɪləm, -lɛm)|
|protoxylem See also metaxylem a plant tissue that conducts water and mineral salts from the roots to all other parts, provides mechanical support, and forms the wood of trees and shrubs. It is of two types (protoxylem and metaxylem), both of which are made up mainly of vessels and tracheids|
|[C19: from Greek xulon wood]|
xylem [%PREMIUM_LINK%] (zī'ləm) Pronunciation Key |
(click for larger image in new window)
A tissue in vascular plants that carries water and dissolved minerals from the roots and provides support for softer tissues. Xylem consists of several different types of cells: fibers for support, parenchyma for storage, and tracheary elements for the transport of water. The tracheary elements are arranged as long tubes through which columns of water are raised. In a tree trunk, the innermost part of the wood is dead but structurally strong xylem, while the outer part consists of living xylem, and beyond it, layers of cambium and phloem. See more at cambium, capillary action. Compare phloem.