Dendroid nature of trees formation of wood - role of cambium - anticlinal & periclinal division.

Dendroid nature of trees formation of wood - role of cambium - anticlinal & periclinal division.

1. Dendroid nature of trees - Formation of wood - Role of cambium - anticlinal & periclinal division. Alex K George I MSc. Forestry

2. WOOD: Nature's Best Building Material One of the oldest construction materials easily produced & handled widely used Only naturally renewable building material Wood is orthotropic, elasto-plasitc , hygroscopic, organic ( 50% C; 44% O; 6% H; 0.1% N ) material

3. Structure of a Tree root system anchor absorption of moisture & minerals trunk support crown transport * structural timber crown produce food, seed

4. Orthotropic Material/ anisotropic Orthotropic means that wood has unique and independent properties in the directions of three mutually perpendicular axes- longitudinal, radial, and tangential.

5. Orthotropic Material The properties of wood parallel to the grain are higher than those perpendicular to the grain.

6. Formation of wood Growth and development of higher plants is governed by cell division (mitotic). 1. Apical meristem – tips – height 2. Lateral meristem – cylindrical column – below bark – vascular cambium – diameter VS : thin meristematic layer located between xylem and phloem.

7. Division of cambial cells – Sachs (1878) Periclinal division – radial direction (inside and outside) Anticlinal division – circumference (side) Periclinal division of cambial cells to produce secondary xylem occurs far more frequently than divisions yielding secondary phloem.

8. Component cells of cambium : squared brick ( c.s ) 1. Fusiform initials – elongate and tapering in vertical orientation – divide to a. vessel elements b. fibers c. axial parenchyma 2. Ray initials – cuboidal – divide to a. ray b. ray parenchyma

9. Thank you.