Exercise 6

• results in an increase in the length of stems and roots and the production of new organs

  Primary growth
• results in an increase in the girth of stems and roots.

  Secondary growth
• the result of the activity of the apical meristem in the stem


  Primary growth in the shoot
• the result of the activity of two lateral meristems: the vascular cambium, xylem and phloem, and phellogen.

  Secondary growth
• which produces the periderm

  cork cambium (phellogen)
• develops as the woody plant ages, and it replaces the epidermis

  Periderm
• Periderm consists of several layers including the


  Cork & cork cambium
• produces cork to the outside

  Cork cambium
• refers to all tissues outside the vascular cambium

  Bark
• is a non-descript layer of cells immediately inside

  the phellogen

  Phelloderm
• These are sheets of cells (parenchyma and sometimes tracheids) that are oriented laterally, and are a system for the lateral conduction of water, minerals, and metabolites

  Xylem & Phloem rays
• pass through the exact center of the stem

  Radial section
• not pass through the stem center

  Tangential section
• the tip of the twig

  terminal bud
• have been left on the twig where the leaves were once located

  leaf scars
• the scars located inside the leaf scars

  Tiny vascular bundle scars
• Small dots along the twig

  Lenticels