Xylem transports water from roots to stems and leaves

The xylem of tracheophytes conducts water from roots to aboveground plant parts. It contains conducting cells called tracheary elements, which undergo programmed cell death before they assume their function of transporting water and dissolved minerals. There are two types of tracheary elements. The evolutionarily more ancient tracheary elements, found in gymnosperms and other tracheophytes, are tracheids— spindle-shaped cells interconnected by numerous pits in their cell walls (Figure 35.9e). When the cell contents—nucleus and cytoplasm—disintegrate upon cell death, water can move with little resistance from one tracheid to its neighbors by way of the pits.

Flowering plants evolved a water-conducting system made up of vessels. The individual cells that form vessels, called vessel elements, must also die

35.10 Evolution of the Conducting Cells of Vascular Systems

The xylem of angiosperms has changed over time. The cells that conduct water and mineral nutrients have become shorter, and the end walls have become more perpendicular to the side walls.

Vessel elements

Tracheids

Vessel elements

Tracheids

Xylem Tracheids And Vessels

(b) Phloem

Sieve cell Sieve tube element

(b) Phloem

Sieve cell Sieve tube element

Companion cell

Sieve plate

Companion cell

Sieve plate

- Pores of sieve plate

- Sieve plate

- Pores of sieve plate

- Sieve plate

Sieve Tube Element

35.11 Sieve Tubes Individual sieve tube elementsjoin together to form long tubes that transport carbohydrates and other nutrient molecules throughout the plant body. Sieve plates form at the ends of each sieve tube element.

35.11 Sieve Tubes Individual sieve tube elementsjoin together to form long tubes that transport carbohydrates and other nutrient molecules throughout the plant body. Sieve plates form at the ends of each sieve tube element.

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Responses

  • mulu selassie
    How can water move from one tracheid into a neighboring cell?
    7 years ago
  • iggi
    Which elements of xylem conduct water?
    7 years ago
  • hagos
    What is xylem vessels and tracheids?
    6 years ago

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