Tracheids

Tracheids are elongated cells in the xylem of vascular plants that serve in the transport of water and mineral salts. Tracheids are one of two types of tracheary elements, vessel elements being the other. Tracheids, unlike vessel elements, do not have perforations.[1]

All tracheary elements develop a thick lignified cell wall, and at maturity the protoplast has broken down and disappeared.[2] The presence of tracheary elements is the defining characteristic of vascular plants to differentiate them from non-vascular plants. Tracheid build varies by location. The two major functions that tracheids may fulfill are contributing to the transport system and providing structural support. The secondary walls have thickenings in various forms—as annular rings; as continuous helices (called helical or spiral); as a network (called reticulate); as transverse nets (called scalariform); or, as extensive thickenings except in the region of pits (called pitted).[3]

Tracheids 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.).

Tracheids provide most of the structural support in softwoods, where they are the major cell type.

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.

See also

References

Further readings

  • 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 in maceration; both in pine.
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.