FPU L3plant origin of wood

• Characteristics of woody plants

  • Must be vascular plants
  • Must be perennial plants
  • Must have a stem that persists through the years
  • Must exhibit secondary thickening
• Softwood vs. Hardwood


  • Gymnosperms produce softwoods
  • Angiosperms produce hardwoods
• Softwoods


  • Cells that serve to transport water also provide the mechanical support for the stem (TRACHEIDS)
• Hardwoods


  • Some cells specialize in water transport (VESSELS), and others in providing mechanical support (FIBERS)
  • Pores can frequently be seen with the naked eye as a number of pinholes in the transverse surface of the wood
  • Hardwoods are commonly referred to as porous woods, and softwoods as nonferrous woods
  • PARENCHYMA in both softwoods and hardwoods functions storage of food
• Tree Growth


  1. The process by which a tree increases in size over time

  2. Trees provide us with oxygen, shade, and a host of other benefits
• The Stem


  • The primary source of wood
  • The main axis that supports leaves, branches, and flowers
  • Consists of bark, cambium, xylem, and phloem tissues
  • Functions: support, conduct, production, storage
  • Types of Stems: herbaceous and woody
  • Factors Affecting Stem Growth: Hormones, environmental factors, and genetic factors all play a role in stem growth
• Primary Growth


  1. Results from cell division in the apical meristem, which produces new cells that differentiate into different tissues, such as xylem, phloem, and cambium

  2. Responsible for the elongation of stems and branches and the production of new leaves and buds
• Secondary growth


  1. Refers to the increase in thickness of a tree or its branches

  2. Occurs in the lateral meristem or cambium, which is located just behind the bark
• Tree-Trunk Development: Primary Growth
• The apical meristem is found at the tip of a shoot (and root), where it forms new leaves (or roots). It also 'spins out’ vascular bundles behind itself as it grows upwards
• Shoot (and root) development

  1. Forms new leaves (or roots)

  2. Spins out vascular bundles as it grows upwards
• Primary Growth


  Refers to the increase in thickness of a tree or its branches
• Secondary Growth


  1. Occurs in the lateral meristem or cambium beneath the bark

  2. Results from cell division in the cambium producing new cells that differentiate into secondary xylem and secondary phloem

  3. Responsible for the increase in girth of the stem or branch, and the production of new bark tissue

  4. Responsible for the formation of annual growth rings in trees
• Cells are the basic structural and physiological unit of wood, as of all plant material
• Cell


  Organizations of cells of one or more types that have a common origin and a common collective function
• Tissue


  Groups of cells of one or more types that have a common origin and a common collective function
• Types of tissues based on functions

  • Conducting (e.g., vessels in hardwood, tracheids in softwoods)
  • Supporting or mechanical (e.g., fibers and tracheids in softwoods)
  • Storage (e.g., parenchyma cells, tracheids)
• Types of tissues based on alignment of wood cells

  • Longitudinal or axial
  • Horizontal or ray
• Types of tissues based on cell formation

  • Meristematic involves in new cell formation
  • Permanent regions within a plant where growth has ceased at least temporarily and in which cells and tissues have become fully differentiated and mature
• Some permanent tissues become meristematic again like the cork cambium
• Chloroplasts are organelles found only in plants, algae, and some protists.
• Light-colored woods are usually used for food supplements
• Dark colored- woods are ideal for decorative purposes