Bark

First year practical course (Botany 1)

1. Bark
First year practical
course (Botany 1)
Presented by:
Shimaa Abdelgawad
Assisting lecturer at
Pharmacognosy
department, Faculty of
pharmacy, Fayoum
University

2. Definition of Bark Definition of Bark
•Barkistheportionofthe
trunk, stem, branches or
roots of woody plants
exterior
to
the
cambium
•It include all the tissues
outsidethecambium.

3. General scheme for description of bark
1. Name
:English,LatinandArabicnames.
2. Origin
:condition, part used, genus,
speciesandfamily.
3. Condition:
fresh or dry; entire or broken
pieces
.
pieces
.
4. Size
:
measure height, width and thickness.
5. Color
:
as seen in bulk.

4. General scheme for description of bark
6. Shapes or forms of bark: Shape of the bark depends on the distribution
and nature of the tissues present and upon the
method of separation and removal of the park method of separation and removal of the park from the plant

5. 6. Shapes or forms of bark:
1-Flat:
Whenderivedfromoldtrunk.Itis
usuallyquiteflatandverythick
2- Curved:
When curved and slightly
concaveontheinnerside
3- Recurved:
When the concave side is
theouterone
4- Channeled:
When deeply concave on
the
inner
side
1 2
4
the
inner
side
5- Single quill:
When deeply concave on
theinnersidethattheedgesofthebark
nearlyorquiteoverlap.
6- Double quill:
When both edges are
separatelyinrolled
7- Compound quill:
When single or
double quills are packed inside one
another
5
6
7

6. : 7. Outer surface
In this item, describes the color of outer
surface of park and any features present like:
•Lenticels
•
Epiphytes:
lichens, liverworts or mosses
•
Epiphytes:
lichens, liverworts or mosses
•Touch:the park may be smooth or showing
longitudinal or transverse furrows or showing
cracks or fissures.

7. : 7. Outer surface
Lenticels:
Placedtransversely, the shape and
abundanceofwhichmayhelpindistinguishing
the bark. Lenticels, are breathing pores for
exchangeofgases,largerinsizeandsmallerin
number
than
stomata
.
number
than
stomata
.

8. : 7. Outer surface
Lichens: •A type of fungus that grows on the
surfaceofbarks.
•Itexistsasagrayishthalloidstructure.
•Growon trees using the bark as a
mediumfortheirnutritionandgrowth.
Liverworts: •Arefoliaceousstructure.
•Consists of very small stems to which
smallleavesareattachedinoneplane.
Mosses: Arestembearingspirallyarrangedleaves
each possesses a midrib and lamina of
onecellthick.

9. : 7. Outer surface
Touch 1-Cracksandfissures:
ariseowingto
continuedincreaseingrowthandto
thelackelasticity.
2- Wrinkles and furrows:
The greater
shrinkageofthesoftertissuesresult
in
formation
of
wrinkles
(because
in
formation
of
wrinkles
(because
the shrinkage of the barks during
dryingoccurchieflytransversely. 3- Smooth:
when the cork is evenly
developed(oryoungertrees).
4-Itmaybescaly
duetoexfoliationof
theoutertissues
Cracks and fissures
Wrinkles and furrows

10. : 8. Inner surface
Itisusuallypalerincolorthanoutersurfaceand
canbedescribedas:
1-Smooth:
duetothepresenceofuniformsoft
innertissue
2
-
Striated
:
when
showing
fine
or
coarse
parallel
2
-
Striated
:
when
showing
fine
or
coarse
parallel
longitudinal ridges, producedas a result of
transverseshrinkage 3-Corrugated:
whenshowingtransverseparallel
wrinkles or folds producedas a result of
longitudinalshrinkage

11. 9. Fracture This term describes how the barks broken
transversely and the character of the broken
surface.
Itisdescribedas: 1-Short:
Whenthefracturedsurfaceissmooth.
2- Splintery:
When sharp and jagged projection are
formed.
Splintery
3- Fibrous:
When fine fibrous threads extend from
thebrokensurface.
4- Granular:
When the surface exhibit small rounded
prominences.
5- Horny:
When hard to broken and exhibiting hard
hornlikebrokensurface.
6-Laminated:
Whenbreaksintoarrangedlayers.
7- Flexible:
When breaking only by tearing or
twisting.
Fibrous
Laminated

12. 10-Histology of bark

13. Formation of bark