L5 Minute Structures of soft woods minute Structure classification

• Minute Structures of Softwoods

  Structures Classification Based on cellular orientation: Transversely oriented cells – perpendicular to longitudinal axis of the stem due to ray initial, Longitudinally oriented cells – parallel to the longitudinal axis of the stem due to fusiform initial, Based on structural type: Parenchymatous – living structures for transport of food and nutrients, Prosenchymatous – dead at maturity for structural support
• Longitudinal Elements


  Longitudinal Prosenchymatous Elements, Longitudinal Tracheids
• Longitudinal Tracheids are the most common elements found in softwoods. They function for mechanical support and conduction in softwoods
• Longitudinal Resinous Tracheids: As longitudinal tracheids of the normal type pass from sapwood into heartwood, resinous materials sometimes accumulate. Rare in softwoods but most frequent in Araucaria and Agathis of the Araucariaceae
• Longitudinal Strand Tracheids arise from further division of a cell which would otherwise have developed into longitudinal tracheids. These are shorter and possess end walls
• Longitudinal Parechymatous Elements


  Longitudinal or Axial Parenchyma: These elements function for storage of food. Its arrangement in softwoods is either diffuse and zonate, and even absent in some species. Benguet pine and Malakauayan have diffuse parenchyma while axial parenchyma is lacking in Almaciga and Igem
• Longitudinal Epithelial Cells surround the resin ducts of some softwood species, like in Benguet pine
• Transverse Elements


  Transverse Prosenchymatous Elements: Ray Tracheids are brick-like appearing cells that comprise the
• Species with different types of parenchyma

  • Benguet pine
  • Malakauayan
  • Almaciga
  • Igem
• Longitudinal Epithelial Cells


  • Surround the resin ducts of some softwood species, like in Benguet pine
• Transverse Elements: Transverse Prosenchymatous Elements

  Ray Tracheids are brick-like appearing cells that comprise the wood rays
• Transverse Elements: Transverse Parenchymatous Elements

  Ray Parenchyma is the parenchyma component of the wood ray. The rectangular areas formed by the walls of ray parenchyma and those of the longitudinal Tracheid as seen in the radial section is called the cross field. The appearance of which is of diagnostic importance for identification
• Ray epithelial cells


  • Cells surrounding the transverse resin canals of softwoods. These canals could be normal or traumatic in origin. When all the transverse prosenchymatous and parenchymatous elements are present together with a canal, the ray is called a fusiform ray