Xylem tissue is a complex tissue which always includes tracheary elements. Xylem serves to transport water up the plant. Tracheary elements have secondary walls with pits and are dead at maturity. If a tracheary element only has pits, it is considered a tracheid. If a tracheary element also has perforations, it is considered to be a vessel element. Conifers only have tracheids. flowering plants can have both.

 

• Link to image of a cross section of Medicago stem showing the detail of a vascular bundle. Xylem is towards the inside, and phloem is towards the outside.

 

• Link to image of a cross section of Medicago stem showing the detail of the xylem facing the pith. The red-stained cells are vessel elements.

 

• Link to image of a cross section of Cucurbita stem showing xylem tissue consisting of vessel elements and parenchyma cells

 

• Link to image of a longitudinal section of Cucurbita stem showing a vessel with pitted secondary walls.

 

• Link to image of a longitudinal section of Cucurbita stem showing vessel elements with incomplete secondary walls.

 

• Link to image of a longitudinal section of Cucurbita stem showing pits.

 

• Link to image of a cross section of Pinus stem showing xylem consisting of tracheid with pits

 

• Link to image of a cross section of Pinus stem showing xylem with tracheids and parenchyma cells.

 

• Link to view of a vessel element of macerated oak wood.

 

• Link to view of tracheid of macerated pine wood.

 

• Pine tracheids showing pits.

 

• Xylem of a carrot root. Tissue consists of vessel element and lots of parenchyma cells.