xylem

(redirected from Woody tissue)
Also found in: Dictionary, Thesaurus, Medical.
Related to Woody tissue: Secondary xylem

xylem

(zī`ləm): see stemstem,
supporting structure of a plant, serving also to conduct and to store food materials. The stems of herbaceous and of woody plants differ: those of herbaceous plants are usually green and pliant and are covered by a thin epidermis instead of by the bark of woody plants.
..... Click the link for more information.
; woodwood,
botanically, the xylem tissue that forms the bulk of the stem of a woody plant. Xylem conducts sap upward from the roots to the leaves, stores food in the form of complex carbohydrates, and provides support; it is made up of various types of cells specialized for each of
..... Click the link for more information.
.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/

Xylem

The principal water-conducting tissue and the chief supporting system of higher plants. This tissue and the associated phloem constitute the vascular system of vascular plants. Xylem is composed of various kinds of cells, living or nonliving. The structure of these cells differs in their functions, but characteristically all have a rigid and enduring cell wall that is well preserved in fossils.

In terms of their functions, the kinds of cells in xylem are those related principally to conduction and support, tracheids; to conduction, vessel members; to support, fibers; and to food storage, parenchyma. Vessel members and tracheids are often called tracheary elements. The cells in each of the four categories vary widely in structure. See Parenchyma

Xylem tissues arise in later stages of embryo development of a given plant and are added to by differentiation of cells derived from the apical meristems of roots and stems. Growth and differentiation of tissues derived from the apical meristem provide the primary body of the plant, and the xylem tissues formed in it are called primary. Secondary xylem, when present, is produced by the vascular cambium. See Lateral meristem

In the trade, softwood is a name for xylem of gymnosperms (conifers) and hardwood for xylem of angiosperms. The terms do not refer to actual hardness of the wood. Woods of gymnosperms are generally composed only of tracheids, wood parenchyma, and small rays, but differ in detail. Resin ducts are present in many softwoods. Woods of angiosperms show extreme variation in both vertical and horizontal systems, but with few exceptions have vessels.

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Xylem

 

a tissue of terrestrial plants that serves to conduct water and mineral salts upward from the roots through the plant. Xylem is distributed as a solid ring or in conducting, or fibrovas-cular, bundles. It consists of conducting cells proper (tracheae [vessels] and tracheids), mechanical cells (libriform), and xylem and ray parenchyma. The walls of all xylem cells lignify. True xylem is characteristic of all pteropsids, gymnosperms, and flowering plants. The xylem of perennial stems and roots is predominantly called wood. Primary xylem arises from the procambium. The first element of the primary xylem to appear is the proto-xylem, which consists of tracheids and vessels with ringed and spiral thickenings of the walls. The metaxylem, which has scalariform and pitted thickenings, forms somewhat later. Secondary xylem is formed by the cambium.

O. N. CHISTIAKOVA

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

xylem

[′zī·ləm]
(botany)
The principal water-conducting tissue and the chief supporting tissue of higher plants; composed of tracheids, vessel members, fibers, and parenchyma.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

xylem

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 (see protoxylem, metaxylem), both of which are made up mainly of vessels and tracheids
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
For the most recent 1999 to 2005 time period, New Jersey forests increased carbon storage (in aboveground woody tissues) at a rate of approximately 2,416,560 tons/yr.
In North America 80% of the population lives in urban centres which are significant users of irreplaceable energy and producers of massive levels of pollution affecting air, land and water To a certain extent, urban trees can capture many of these pollutants and either use them or store them in woody tissues. Carbon sequestration by world forests is becoming part of the informed public's understanding about the value of trees to our global livelihood.
Freezing stress response in woody tissues observed using low temperature scanning electron microscopy and freeze substitution techniques.
As various wood-digesting fungi, beetles, and crustaceans work to decompose the woody tissues, they attract insects, lizards, tree frogs, etc., which in turn draw desirable songbirds such as titmice, bluebirds, chickadees, and wrens.
And unlike some nutrients, calcium can't be recycled from woody tissues; once bound, it tends to remain there.
Like other tree plants, Jatropha takes carbon from the environment and deposits in the woody tissues of the stem.
This should probably be more pronounced in old stems and roots than in shoots as it appears that the canopy retains more stable nutrient concentrations than the woody tissues (Adams et al.
The changes of nutrient content in stems and roots of de-budded plants that were likely to take place as a consequence of accumulation of resorbed nutrients from C + 1 leaves in the woody tissues after removal of the nutrient sinks in current leaves were quantified in a similar way by comparing the pool sizes in woody parts of de-budded and control plants.