Tracheid

Tracheid

Tracheids are elongated cells in the xylem of vascular plants, serving in the transport of water and mineral salts. The build of tracheids will vary according to where they occur.

Tracheids are one of two types of tracheary elements, vessel elements being the other. All tracheary elements will develop a thick lignified cell wall, and at maturity the protoplast has broken down and disappeared. The presence of tracheary elements is the defining characteristic of vascular plants to differentiate them from non-vascular plants.

The two major functions that tracheids may fulfill are
* as part of the transport system
* in structural support

In most cases, the prime function of tracheids is that of transporting water. They occur in vascular bundles throughout the non-woody parts of the vascular plant and provide water and minerals collected by the roots to leaves and other parts of the plant (stem, flowers, fruits etc).

A good example of structural support is in softwoods where tracheids are the major cell type. Tracheids give softwood its strength.

Because tracheids have a much higher surface to volume ratio compared to vessel elements, they serve to hold water against gravity (by adhesion) when transpiration is not occurring. This is likely one mechanism that helps plants prevent air embolisms.

ee also

* Vessel element
* Xylem

References

* Wilson, K. & D.J.B. White (1986). "The Anatomy of Wood: its Diversity and variability." Stobart & Son Ltd, London

External links

*Pictures of softwood tracheids [http://botweb.uwsp.edu/anatomy/images/gymnospermwood/pages/Anat0288.htm in cross section] and [http://botweb.uwsp.edu/anatomy/images/xylemdevelopment/pages/Anat0182.htm in maceration] ; both in pine.


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Look at other dictionaries:

  • Tracheid — Tra che*id, n. (Bot.) A wood cell with spiral or other markings and closed throughout, as in pine wood. [1913 Webster] …   The Collaborative International Dictionary of English

  • tracheid — [trā′kēid] n. [ TRACHE(O) + ID] Bot. a type of long, thick walled, tubelike, nonliving cell found in xylem, esp. of the conifers tracheidal adj …   English World dictionary

  • tracheid — noun Etymology: International Scientific Vocabulary Date: 1875 a long tubular pitted cell that is peculiar to xylem, functions in conduction and support, and has tapering closed ends and thickened lignified walls …   New Collegiate Dictionary

  • tracheid — Water conducting cell forming part of the plant xylem. Contains thick, lignified secondary cells walls, with no protoplast at maturity. Interconnects with neighbouring tracheids through pits; the end walls are not perforated (cf. vessel elements) …   Dictionary of molecular biology

  • tracheid — tracheidal /treuh kee i dl, tray kee uyd l/, adj. /tray kee id/, n. Bot. an elongated, tapering xylem cell having lignified, pitted, intact walls, adapted for conduction and support. Cf. vessel (def. 5). [1870 75; TRACHE(A) + ID3] * * * ▪ plant… …   Universalium

  • tracheid —   Xylem cell with thickened pitted or annular walls and tapered ends …   Expanded glossary of Cycad terms

  • tracheid — tra·cheid …   English syllables

  • tracheid — tra•che•id [[t]ˈtreɪ ki ɪd[/t]] n. bot an elongated, tapering xylem cell having woody, pitted, intact walls, adapted for conduction and support Compare vessel 4) • Etymology: 1870–75 …   From formal English to slang

  • tracheid — /ˈtreɪkiɪd/ (say traykeeid) noun an elongated, imperforate, dead xylem cell with a lignified wall. Also, tracheide …  

  • tracheid — An elongated, tapering xylem cell, with lignified pitted walls, adapted for solute conduction and physical support. Found in conifers, ferns and related plants …   Glossary of Biotechnology

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