CINNAMON BARK microscopy.

1. CINNAMON BARK
There are two plant species of Cinnamon barks.
1] Cinnamomum zeylanicum: It is inner bark, the meaning is, it does not contain phellem, phellogen
and phelloderm layers which is usually present in periderm of most of barks.
2] Cinnamomum cassia bark: It is entire bark, the meaning is, it does contain phellem, phellogen and
phelloderm layers which is usually present in periderm of most of barks.
Because of above difference we can find out significant microscopic difference between Cinnamomum
zeylanicum and Cinnamomum cassia bark.
Cassia bark is cheap bark and easily available so it is usually taken up for microscopy study.
Biological Source: Cinnamon is the dried inner bark of the coppiced shoots of Cinnamomum
zeylanicum Nees., belonging to family Lauraceae.
Synonyms
Ceylon cinnamon
Cortex cinnamon
Saigon cinnamon
Chinese cassia
Cinnamomum aromaticum
Cinnamomum laurus.
Morphology of bark:
1. Cinnamon bark are either in single- or double-compound quills, with a size of 1 m length, 0.5
mm thickness, and 6 to 10 mm diameter.
2. The outer surface has yellowish brown to light brown in colour. Its having longitudinal lines or
striations due to presence of pericyclic fibre and it bears scars and minute holes or pores
representing scars of leaves or the lateral shoots.
3. The inner surface is darker than the outer.
4. Cinnamon has a fragrant perfume; taste aromatic and sweet.
5. It brakes with splintery fracture that is appearance of broken surface having pointed
projections.
Microscopy of transverse section of bark:
1. It is inner bark, the meaning is, it does not contain phellem, phellogen and phelloderm layers
which is usually present in periderm of most of barks. Periderm layer is removed during drying
of bark which results absence of cork or phellem, phellogen and phelloderm. Hence periderm
does not find in transverse section of Cinnamomum zeylanicum bark.

2. 2. The transverse section of bark shows the presence of three to four layers of sclereids cells or
stone cells which contain thicker wall towards inner side while thinner towards outer side more
or less horse shoe shaped outline of stone cells. The wall of stone cell thickened by lignin
which is best visualised by staining reagent of phloroglucinol and concentrated hydrochloric
acid (1:1 ratio). Lignin shows colour reaction (pink colour) in presence of phloroglucinol and
concentrated hydrochloric acid. This will helpful for differentiating the stone cells from other
cells like phloem parenchyma.
3. Parenchyma cells consisting of minute size of starch grains.
4. The pericyclic fibres (6 to 15) are present on the outer margin. These cells are slightly lignified
and present in groups.
5. Secondary phloem present towards inner side of transverse section of bark or adjacent to layers
of sclereid cells. It consists of sieve tubes which are completely collapsed and are arranged
tangentially;
6. lignified phloem fibres, arranged as tangential rows of four to five cells; biseriate medullary rays
with needle-shaped calcium oxalate crystals;
7. Medullary rays are biseriate, tangential to secondary phloem, wider towards outer side while
narrow towards inner side.
8. longitudinally elongated idioblast of phloem consisting of volatile oil; known as oil cells. These
are fill with volatile oils of pharmaceutical importance.
9. Sub-rectangular phloem parenchyma cells filled with minute size starch grains and microcrystal
of calcium oxalate crystals.
(Diagrammatic representation of T.S.) Cinnamomum zeylanicum bark

3. Transverse section of Cinnamomum zeylanicum bark
-----------------------------------------------------------------------------------------------------------------------------------
Cinnamon cassia is used as a substituent species of Cinnamomum zeylanicum bark.
Synonyms: Cinnamomum cassia, called Chinese cassia or Chinese cinnamon.
Biological source: It consists of dried stem bark of the plant Cinnamomum cassia Blume.
Family: Lauraceae
Macroscopical Character:
i. Colour: Dark brown outside, light brown on inner side.
ii. Odour: Characteristic, sweet, aromatic.
iii. Taste: Slightly sweet, spicy.
iv. Size: 5 to 40 x 12 to 18 x 1 to 3 mm.
v. Shape: Single squill or channelled pieces.
vi. Fracture: Short granular on outer part, splintery on inner part.
Morphology of cassia bark:
1. Cinnamon bark are chanelled pieces, concave towards inner side while convex towards
outerside with a size of 1 m length, 0.5-1 mm thickness, and 6 to 10 mm diameter.
2. The outer surface has yellowish brown to light brown in colour. Its having longitudinal lines or
striations due to presence of pericyclic fibre and it bears scars and minute holes or pores
representing scars of leaves or the lateral shoots.
3. The inner surface is lighter than the outer.
4. Cinnamon has a fragrant perfume; taste aromatic and sweet.

4. 5. It brakes with splintery fracture that is appearance of broken surface having pointed
projections.
Microscopical characters:
1. Periderm:
a. Cork:
It consists of several layers of radially arranged rows of thin walled cells with dark brown contents.
The cork cells are impregnated with suberin that’s why this layer is darker in colour.
b. Phellogen: It consists of 2-3 layers of thin walled rectangular cells without any cellular contents. It
is undistingwishable from phelloderm layer.
c. Phelloderm: 6 to 8 layers of thin walled rectangular cells without any cellular contents. Like cork,
they are arranged at times in radial rows.
2. Cortex: They consist of several layers of thin walled and tangentially elongated cells containing
yellowish brown matter. Some of the cortical cells are filled with microsphenoidal crystals of calcium
oxalate and minute starch grains.
3. The pericyclic fibres (6 to 15) are present on the outer margin. These cells are slightly lignified
and present in groups.
4. Secondary phloem: It consists of phloem parenchyma, phloem fibres and medullary rays and oil
cells. Secondary phloem present towards inner side of transverse section of bark or adjacent to layers
of sclereid cells. It consists of sieve tubes which are completely collapsed and are arranged
tangentially; lignified phloem fibres, arranged as tangential rows of four to five cells; biseriate
medullary rays with needle-shaped calcium oxalate crystals. Sub-rectangular phloem parenchyma
cells filled with minute size starch grains and microcrystal of calcium oxalate crystals.
5. Medullary rays: Medullary rays transverse radially the phloem parenchyma; 1 to 3 cells wide,
extend up to cortex, cells radially elongated and contain starch grains. Medullary rays are biseriate,
tangential to secondary phloem, wider towards outer side while narrow towards inner side.
6. longitudinally elongated idioblast of phloem consisting of volatile oil; known as oil cells. These are
fill with volatile oils of pharmaceutical importance.

6. Powder Microscopy of Cinnamomum cassia bark.
1. 1a. A single fibre and part of a fibre, centrally slit shaped septum present, both end of fibre
pointed.
2. Sclereids with associated parenchymatous cells. 2a. Different types of sclereids due to
lignification. It may be horse shoe shaped of U- shaped lignification, few have narrow lumen
due to excessive lignification.
3. Starch granules: small size simple and compound types of starch granules present inside
parenchyma cells of cortex and cells of secondary phloem and medullary rays.
4. Cork in surface view. Cells are compactly arranged, hexhagonal and pentagonal in surface few
with dark brown colour cell walls.
5. Part of phloem in radial longitudinal section showing a fibre, part of an oil cell (oc),
parenchyma, and a medullary ray with some of the cells containing acicular crystals of calcium
oxalate (co).
6. Part of the phloem in tangential longitudinal section showing an oil cell (oc) with associated
fibres, parenchyma, and part of a medullary ray with some of the cells containing acicular
crystals of calcium oxalate.
7. Selereids and fibre of the pericycle.
8. Part of the cork in sectional view showing the alternating layers of thin-walled and thicker
walled cells.
Source:
https://www.britannica.com/topic/cassia-spice
Jackson and Snowdon, 1990.)