Xylem and phloem | Biology for GCSE/IGCSE - Year 11 PDF Download

The Xylem & Phloem

• Plants have two types of transport vessels:
  • Xylem vessels: responsible for transporting water and minerals from the roots to the stem and leaves.
  • Phloem vessels: transport food materials like sucrose and amino acids from the photosynthesizing leaves to non-photosynthesizing areas in the roots and stem.
• These vessels are organized in groups known as vascular bundles, present throughout the root, stem, and leaves.

Adaptations of Xylem Vessels: Extended

• Function: Xylem vessels serve as the transport tissue responsible for conveying water and essential nutrients throughout the plant.
• Adaptations: These adaptations enhance the efficiency and structural integrity of xylem vessels:
  • Xylem cells are interconnected end to end without the presence of cross walls, creating a continuous tube structure. This seamless arrangement aids in the uninterrupted flow of water from roots to leaves.
  • The cells comprising xylem vessels are predominantly devoid of living contents, ensuring unimpeded water movement through them.
  • The outer walls of xylem cells are reinforced with lignin, a strengthening compound that fortifies the tubes, providing structural support to the plant.

These adaptations collectively enable xylem vessels to efficiently transport water and maintain the structural stability of plants.