Bark 6

Bark,
Wood
And
Galls
Lecture-6
By
Dr. Ahmed Metwaly

1. Definition.
2. Kinds.
3. Structure.
4. Quassia wood.
5. Guaiacum wood.
6. Sandal wood.

 The wood is the portion of the trunk, stem,
branches or roots of woody plants inside
the vascular cambium.

Sap wood Heart wood
It is a living wood.
Lighter in colour
•It contains reserve food
material, e.g. starch.
* It may be formed of whole
xylem or only its outer
layers.
•Function: Conductive and
support.
e.g. Quassia wood
* It is a dead wood.
Darker in colour
* It is originally a sap wood
in which the vessels axe
blocked by Tyloses.
* It forms the inner part of
xylem or the whole xylem
* Function: support.
e.g. Guaiacum wood.
Kinds of woods

The wood or xylem is formed of:
Fibres Tracheids Vessels Wood parenchyma Medullary rays
All the wood elements are lignified and acquire a deep red
color with phloroglucin and HCl.

Wood
Fibres
* Each fibre is a single, non-living, elongated cell, and having
usually very long tapering ends, very thick, lignified, pitted
walls and a narrow lumen
Tracheids * Elongated cells having thick lignified walls.
* The walls are pitted with bordered pits.
* They serve for conduction of water.
Vessels * Are long tubes. (number of cells placed end to end).
* The vessels may be:
a) Annular (the thickening is in the form of separate rings).
b) Spiral (the thickening is spirally coiled around the vessel).
c) Reticulate (the thickening meet together forming a network).
d) Pitted (the thickening leaving very small pits).
e) Scalariform (the thickening occurs as a ladder).
Medullary
rays
* Are regular bands of radially elongated parenchyma. It may be;
a) Primary medullary rays (running from the pith to the
pericycle).
b) Secondary medullary rays (running between xylem and

 When the vessel stops its function, the
parenchyma around it grows inside the vessel
through the pits, so the vessels become
blocked. These inner growths are called
tyloses e.g. Guaiacum wood.

 Origin: Dried wood of the trunk branches of
Picrasma excelsa (known as Jamaica quassia)
and Quassia amara (known as Surinam
quassia). Family Simarubaceae.

Shape Occurs in the form of chips and rarely as small cubes.
Color Yellowish-white to yellow.
Odor Odorless
Taste Intensely bitter taste.

the powder is characterized by the following
elements :
1) Fragments of wide bordered pitted xylem vessels.
2) Fragments of wood fibers with thin walls and linear
pits.
3) Fragments of rectangular and lignified wood
parenchyma.
4) Fragments of calcium oxalate prisms (absent in
Surinam quassia).
5) Fragments of madullary rays With underlying
fibers.
Some of the cell contain starch granules or prisms of
Ca-ox.The cell are pitted.

 Bitter principles (Picrasmin, Quassin and
Neoquassin).
 Alkaloids (cathine-6-one)
 Coumarins (scopoletin)

1) Parasiticide for head and body lice.
2) As enema to expel threadworms.
3) Insecticide against certain agricultural
insects.

 Origin: The heart wood of Guaiacum
officinale and Guaiacum sanctum. Family
Zygophllaceae.

 Resins 15–20%. Guaiaretic acid,
dihydroguaiaretic acid and guaiacin.
 Simple phenolics (guaiacol)
 Sesquiterpenes (guaiol)

 useful in chronic gout
 Antirheumatic.
 Anti-inflammatory.

An alcoholic solution gives a deep blue colour
on the addition of oxidizing agents such as
ferric chloride.
This colour is destroyed by reducing agent.

Origin:
It is obtained from Santalum album. Family
Santalaceae
Active Conistetuents:
Volatile oil, the chief constituents of the oil is
the alcohol Santalol.
Uses:
1) A source of volatile oils.
2) The oil is a stimulant and disinfectant of
the whole genitor- urinary tract.

Bark 6

More Related Content

What's hot (6)

Viewers also liked (20)

Similar to Bark 6 (20)

More from Ahmed Metwaly (20)

Recently uploaded (20)

Bark 6