xylem


Also found in: Dictionary, Thesaurus, Medical, Wikipedia.

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.
.

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.

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

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.

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
References in periodicals archive ?
About Xylem Xylem (XYL) is a leading global water technology provider, enabling customers to transport, treat, test and efficiently use water in public utility, residential and commercial building services, industrial and agricultural settings.
To support the dewatering project, Xylem installed 15 Godwin diesel-driven pumps, deployed from the U.
Xylem continues to build on a legacy of addressing global water challenges by supporting the development of sustainable products and services through partnerships with innovators like Rentricity.
Increased wastewater reuse capability has the potential to bring wide-ranging benefits to communities and businesses in the Middle East," explained Andre Dhawan, president of Xylem Europe, the Middle East, India and Africa (EMEIA).
Xylem (XYL) is a global water technology provider, enabling customers to transport, treat, test and efficiently use water in public utility, residential and commercial building services, industrial and agricultural settings.
Based out of a west Eugene warehouse on Highway 99, Xylem celebrated its 10th anniversary last spring.
Being able to study embolism formation and the connections between xylem tissues in such fine detail will help scientists determine how plants respond to water stress and other changing environmental conditions.
There are five main sources of new information that now change our ideas on how monocot xylem evolved.
We propose a classification of the vascular bundles into four types considering their shape, the shape of the xylem ends, the number of protoxylem zones and the presence of parenchyma bands in the xylem.
Torus-bearing pit membranes are present in secondary xylem (wood) and largely or completely absent from primary xylem.
The installation allows people to listen to water moving up inside the trunk through the tree's Xylem cells from the roots to the leaves.
The GWSS may feed on the xylem fluid from hundreds of plant species from 37 families (Turner & Pollard 1959; Redak et al.