Xylem

Definition

Xylem is a type of vascular tissue in plants responsible for the transport of water and nutrients from the roots to the rest of the plant. It also provides structural support to the plant.

5 Must Know Facts For Your Next Test

1. Xylem consists mainly of tracheids and vessel elements, which are specialized cells that facilitate water transport.
2. The primary xylem forms during primary growth, while secondary xylem forms during secondary growth (wood formation).
3. Xylem also contains fibers and parenchyma cells that contribute to its supportive and storage functions.
4. It works through a process called transpiration, where water evaporates from leaves, creating a negative pressure that draws water upwards.
5. Unlike phloem, xylem transports water unidirectionally—from roots to leaves—without requiring energy input (passive transport).

Review Questions

• What are the main components of xylem tissue?
• How does xylem contribute to a plant's structural support?
• Explain how transpiration aids in the movement of water through the xylem.

Related terms

Phloem:

A type of vascular tissue in plants responsible for transporting sugars and other metabolic products downward from the leaves.

Transpiration:

The process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released into the atmosphere.

Tracheid: An elongated cell in the xylem of vascular plants that serves in the transport of water and mineral salts.