Stems, Roots and Leaves

• Dicotyledonous (dicots) plants


  • Seeds contain two cotyledons (seed leaves)
  • Network of veins
  • Leaves have broad blades (leaf surface) and petioles (stalks)
  • Tap root with lateral branches
• Herbaceous dicots


  Have a relatively short life cycle (one growing season) and non-woody tissue
• Transport systems in plants

  • Xylem
  • Phloem
• Plants need transport systems to meet their metabolic demands, to efficiently move substances up and down, and to compensate for their relatively small SA:V ratio
• Plants have a vascular system which involves a network of vessels (vascular tissue) running through the leaves, stem and roots
• The vascular system is comprised of xylem and phloem
• Xylem


  Transports water and mineral ions from the roots to the rest of the plant
• Phloem


  Transports substances from the source (e.g. leaf) to the sink (e.g. root)
• The xylem and phloem are arranged together in vascular bundles
• The vascular bundles are laid out differently in the leaves, stem and roots