Dictionary > Tracheid

Tracheid

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:


You will also like...

Control of body movement
Control of Body Movement

Some of the body movements can be controlled at will, others cannot. The body has a motor program, which is the pattern ..

Pollution in Freshwater Ecosystems
Pollution in Freshwater Ecosystems

There are many environmental factors that arise due to the usage of water in one way or another and for every action tha..

Non-Mendelian Inheritance
Non-Mendelian Inheritance

In this tutorial, find out more about certain types of inheritance that does not follow the Mendelian inheritance patter..

Birth of a Human Baby
Birth of a Human Baby

Following nine months inside the mother's womb is the birth of the baby. Know the different stages of the birthing proce..

Hominid
The Hominids

The hominid family diversified from the apes around 6 to 8 million years ago. Since then, the evolutionary path has prov..

Selective Breeding
Selective Breeding

Gregor Mendel's studies into Monohybrid and Dihybrid crossing and Charles Darwin's study of evolution and natural select..