Question

Write short notes on tracheids.

Answer 1

• Xylem tracheids are elongated with tapering ends and broad lumen. The secondary wall of these cells is lignified.
• They appear as polygonal and thick-walled. Pits are simple or bordered. The cell wall thickenings are due to the deposition of secondary wall substances.
• They are annular, spiral, scalariform, reticulate and pitted. The tracheids are imperforate cells with bordered pits on their end walls.
• Tracheids are chief water-conducting elements in gymnosperms and pteridophytes.
• The conduction of water and mineral salts takes place through the bordered pits. They also offer mechanical support to the plants.