Definition
noun, plural: tracheids
(botany) A tubular cell in the xylem of vascular plants whose primary function is to conduct water and mineral salts, provide structural support, and prevent air embolism in vascular plants
Supplement
The xylem is the vascular tissue responsible for the upward conduction of water and nutrients from the roots. The xylem tissue moves water and nutrients to various parts of the plant such as shoots and leaves. Its major components include xylem parenchyma, xylem fibers, tracheids, and xylem vessels.
Tracheids are one of the two types of tracheary elements of vascular plants. (The other being the vessel elements). A tracheid cell loses its protoplast at maturity. Thus, at maturity, it becomes one of the non-living components of the xylem. Tracheid cells are tube-like with tapering ends. The average length is 5 to 6 mm. The cells have primary and secondary cell walls. The secondary cell wall is lignified and forms in between the primary cell wall and the plasma membrane in various thickening patterns. The most common patterns are annular, spiral, scalariform, reticulate, and pitted. When viewed from the top, the cells appear angular and polygonal. Tracheids have pits, which are concave depressions on the cell wall. In general, each of the pits has a complimentary pit on the neighboring tracheid cell. These pits that are complimentary are called pit pairs. Through them, water can move across from one tracheid cell to another.
In pteridophytes, tracheids are the only water conducting elements. In gymnosperms, the wood is composed chiefly of tracheids. Conifers lacking vessel elements produce the so-called softwood.
See also:
Dictionary > Tracheid
You will also like...
![green leaf - close up view](https://www.biologyonline.com/wp-content/uploads/2020/02/Leaves-253x168.jpg)
Leaves
Leaves are the major photosynthetic organ of a plant. Apart from that, they are also crucial to water movement. In this ..
![Young plant growing from the soil.](https://www.biologyonline.com/wp-content/uploads/2020/02/Soils-257x168.jpg)
Soils
Nutrients in the soil are essential to the proper growth of a land plant. This tutorial deals with the properties of soi..
![Freshwater lake ecosystem](https://www.biologyonline.com/wp-content/uploads/2020/02/Freshwater-Producers-and-Consumers-238x168.jpg)
Freshwater Producers and Consumers
Freshwater ecosystem is comprised of four major constituents, namely elements and compounds, plants, consumers, and deco..
![Selective Breeding](https://www.biologyonline.com/wp-content/uploads/2020/02/Selective-Breeding-252x168.jpg)
Selective Breeding
Gregor Mendel's studies into Monohybrid and Dihybrid crossing and Charles Darwin's study of evolution and natural select..
![3D rendering of an antibody](https://www.biologyonline.com/wp-content/uploads/2020/02/Passive-and-Active-Types-of-Immunity-294x168.jpg)
Passive and Active Types of Immunity
Lymphocytes are a type of white blood cell capable of producing a specific immune response to unique antigens. In thi..
![Adaptive Radiation](https://www.biologyonline.com/wp-content/uploads/2020/02/Adaptive-Radiation-252x168.jpg)
Adaptive Radiation
The diversification of several new species from a recent ancestral source, each adapted to utilize or occupy a vacant ad..