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)
1. Periclinal division – radial direction (inside and
outside)
2. 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

12. Thank you.