[zahy-luhm, -lem]
noun Botany.
a compound tissue in vascular plants that helps provide support and that conducts water and nutrients upward from the roots, consisting of tracheids, vessels, parenchyma cells, and woody fibers.

1870–75; < German, equivalent to Greek xýl(on) wood + -ēma (see phloem)

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World English Dictionary
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]

Collins English Dictionary - Complete & Unabridged 10th Edition
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Word Origin & History

"woody tissue in higher plants," 1875, from Ger. Xylem, coined from Gk. xylon "wood," of unknown origin.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Science Dictionary
xylem  [%PREMIUM_LINK%]     (zī'ləm)  Pronunciation Key 

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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.

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American Heritage
Cultural Dictionary
xylem [(zeye-luhm)]

The system of vessels that transports water in a plant. (See phloem.)

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
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Published by Houghton Mifflin Company. All rights reserved.
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Example sentences
The xylem in trees, through which water rises to the leaves, consists of spaces left by dead cells.
Xylem parenchyma xylem parenchymatous cells are living cells present in xylem.
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