BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

VII. PLANT TISSUES

Vascular Tissues

Tracheids

Unicellular xylem conducting elements, evolutionarily older than vessels, taking the form of long, dead prosenchymatous Cells with oblique transverse walls. In angiosperms, their length ranges from 0.5-1 mm, while in gymnosperms it reaches up to 4 mm. The Cell wall of tracheids features pits and secondary thickenings of various shapes, which determines their specific names (spiral, annular, scalariform, pitted). Tracheids connect with one another at their oblique ends via pits. In gymnosperms, due to the thickening of their secondary wall, tracheids also perform a mechanical function.

Tracheids and vessels in herbaceous plants die off along with them at the end of the vegetative season, whereas in woody plants they persist throughout their lifetime. In the latter, after a few years, vessels and tracheids become plugged with tyloses, as well as organic or inorganic substances. (A tylosis is an outgrowth of an adjacent living parenchymatous cell that penetrates into the vessel lumen through pits).



Last update: 07/08/2026

Editorial and Educational Adaptation: This material has been compiled based on the primary/original source text. The project team performed an editorial review, corrected technical inaccuracies, structured sections, and adapted the content for an educational format.

What was processed:

  • elimination of formatting defects (OCR errors, structural breaks, corrupted characters);
  • editorial organization of content;
  • standardization of terminology in accordance with academic sources;
  • verification of factual statements against the original source text.

All mentions of the author, publication year, and origin of the primary text have been preserved in accordance with the source.