Microscopy/Anatomy/Powder Microscopy Fennel, Cinnamon, Liquorice, Datu

Microscopy/Anatomy/Powder Microscopy (Fennel, Cinnamon, Liquorice, Datura, Rauwolfia, Nux vomica, Senna, Ephedra)

Reading File

This is a broad pharmacognosy practical topic set. It can be organized as:

Microscopy and anatomy
- Diagnostic transverse-section features
- Tissue systems, vascular arrangement, inclusions, and identifying characters
Powder microscopy
- Diagnostic fragments in powdered drugs
- Starch grains, sclereids, fibres, vessels, trichomes, crystals, calcium oxalate, and alkaloid-containing tissues
Individual crude drugs
- Fennel
- Cinnamon
- Liquorice
- Datura
- Rauwolfia
- Nux vomica
- Senna
- Ephedra

High-yield approach: learn each drug under the same headings: biological source and family, macroscopic characters, T.S./anatomy, powder characters, chief constituents, and identification points. In practical exams, the distinguishing microscopic structures carry the most weight, for example: vittae in fennel, sclereids and oil cells in cinnamon, abundant starch in liquorice, covering and glandular trichomes in datura, and characteristic fibres/crystals in the others.

Which format would you like for the detailed notes?

Create a comparison table for all eight drugs

Finding Sources

Searching PubMed

medicinal plants AND microscopy

Searching the Web

pharmacognosy powder microscopy fennel cinnamon liquorice datura rauwolfia nux vomica senna ephedra diagnostic characters

Comparison table: microscopy, anatomy, and powder characters

Drug	Biological source and family	Key anatomy / transverse-section characters	Diagnostic powder microscopy	Major constituents
Fennel	Dried ripe fruits of Foeniculum vulgare; Apiaceae	Fruit is a cremocarp with five primary ridges and four secondary ridges. Mesocarp contains prominent vittae (oil ducts), usually 6: four dorsal and two commissural. Endosperm is large, oily, and has aleurone grains.	Polygonal epidermal cells; fragments of ridges; vittae with volatile oil; spiral/reticulate vessels; parenchyma containing fixed oil and aleurone grains.	Volatile oil, chiefly anethole, with fenchone and estragole.
Cinnamon	Dried inner bark of shoots of Cinnamomum verum; Lauraceae	Cork may be absent or scanty in commercial bark. Cortex has oil cells, mucilage cells, and groups of sclereids. Secondary phloem is broad with fibres and phloem parenchyma. Medullary rays are narrow.	Brown cork cells; thick-walled sclereids; lignified fibres; fragments of phloem; starch grains; oil cells, often containing yellowish-brown volatile oil.	Volatile oil, chiefly cinnamaldehyde; eugenol, tannins, mucilage.
Liquorice	Dried roots and stolons of Glycyrrhiza glabra; Fabaceae	Periderm externally. Cortex is parenchymatous, often with starch. Secondary phloem and xylem are well developed. Xylem has broad vessels and fibres. Medullary rays are distinct. No calcium oxalate crystals is a useful practical point.	Numerous simple and compound starch grains; pitted/reticulate vessels; lignified fibres; parenchyma; cork fragments. Characteristically lacks calcium oxalate crystals.	Glycyrrhizin or glycyrrhizic acid, flavonoids such as liquiritin, sugars and starch.
Datura	Dried leaves of Datura stramonium; Solanaceae	Dorsiventral leaf. Epidermis bears wavy-walled cells, anisocytic stomata, covering trichomes and glandular trichomes. Palisade tissue occurs below upper epidermis. Midrib contains a bicollateral vascular bundle. Calcium oxalate crystals may occur.	Epidermal fragments with anisocytic stomata; multicellular uniseriate covering trichomes; capitate glandular trichomes; spiral vessels; calcium oxalate crystals.	Tropane alkaloids: hyoscyamine, atropine, scopolamine.
Rauwolfia	Dried roots of Rauvolfia serpentina; Apocynaceae	Outer cork is multilayered. Cortex is broad and parenchymatous, containing starch. Phloem occurs in patches; secondary xylem has vessels, fibres and rays. Characteristic laticiferous tissue may be present.	Cork cells; abundant starch grains; lignified fibres; pitted and reticulate vessels; phloem parenchyma; occasional latex-containing elements.	Indole alkaloids: reserpine, rescinnamine, deserpidine, ajmaline and ajmalicine.
Nux vomica	Dried seeds of Strychnos nux-vomica; Loganiaceae	Seed coat has an outer epidermis with long, thick-walled, lignified unicellular hairs radiating from the surface, giving a silky appearance. Endosperm is large, horny, and contains fixed oil and aleurone grains. Embryo is small.	Characteristic long, thick-walled, lignified seed-coat hairs; fragments of endosperm with aleurone grains and fixed oil; no starch grains.	Indole alkaloids: strychnine and brucine.
Senna	Dried leaflets of Senna alexandrina or Cassia angustifolia; Fabaceae/Caesalpiniaceae	Dorsiventral leaf with upper and lower epidermis. Stomata are mainly paracytic. Palisade tissue is usually single layered. Midrib contains collateral vascular tissue. Covering trichomes are present; calcium oxalate crystals may occur.	Epidermal fragments with paracytic stomata; unicellular warty covering trichomes; palisade cells; spiral vessels; calcium oxalate crystals; fragments of veins.	Hydroxyanthracene glycosides, especially sennosides A and B.
Ephedra	Dried young stems of Ephedra gerardiana or Ephedra sinica; Ephedraceae	Stem shows a ridged outline. Epidermis has thick cuticle and sunken stomata. Hypodermis is sclerenchymatous. Cortex is chlorenchymatous. Vascular bundles are arranged in a ring; xylem contains vessels and fibres. Pith is large.	Epidermal fragments with sunken stomata; cuticular fragments; fibres; spiral, annular and pitted vessels; chlorenchymatous cells.	Protoalkaloids: ephedrine and pseudoephedrine.

Rapid identification points

Drug	Best spot character
Fennel	Vittae or oil ducts in fruit
Cinnamon	Sclereids plus oil cells in bark
Liquorice	Abundant starch with vessels and fibres, but no calcium oxalate crystals
Datura	Anisocytic stomata with covering and glandular trichomes
Rauwolfia	Root powder with starch, fibres, vessels and alkaloid-containing/laticiferous elements
Nux vomica	Long, lignified, radially arranged seed-coat hairs
Senna	Paracytic stomata and warty unicellular trichomes
Ephedra	Stem epidermis with sunken stomata and thick cuticle

Microscopy remains a practical method for authenticating crude herbal drugs, though it is less reliable after extensive processing or in complex mixtures, as reviewed in this microscopic-authentication paper.

Explain with a neat labelled diagram the microscopy and powder microscopical characters of Cassia cinnamon for 10 m

Reading File

Finding Sources

Searching Images

Cinnamomum cassia cinnamon bark transverse section labelled microscopy oil cells sclereids phloem diagram

Searching PubMed

Cinnamomum cassia pharmacognosy microscopy

Searching the Web

Cinnamomum cassia bark transverse section powder microscopy characters oil cells sclereids

Generating Image

A clean, exam-ready labelled botanical line diagram of a transverse section of Cassia cinnamon bark (Cinnamomum cassia). Show a curved bark section from outer to inner surface, with labels for cork/periderm, cortex with stone cells and mucilage cells, oil cells, primary phloem, secondary phloem, phloem fibres, and medullary rays. Include a separate inset of diagnostic powder microscopy fragments: thick-walled stone cell, lignified fibre, oil cell, starch grains, and pitted vessel. Use accurate black ink textbook line-art, clear labels, and no decorative elements.

Cassia cinnamon: microscopy and powder microscopy

Biological source: Dried bark of Cinnamomum cassia (syn. Cinnamomum aromaticum), family Lauraceae. It is also called Chinese cinnamon.

Labelled T.S. and powder microscopy of Cassia cinnamon

A. Microscopy of bark: transverse section

A transverse section of Cassia cinnamon bark shows the following diagnostic layers, from outside inward:

Cork / periderm
- Present as several layers of compact, rectangular to polygonal, brownish cork cells.
- This is a useful distinction from true cinnamon (C. verum), in which cork is commonly absent in commercial bark.
Cortex
- Broad, made up of parenchymatous cells.
- Contains many starch grains.
- Scattered oil cells are present. They are rounded or oval and contain volatile oil.
- Groups of large, thick-walled, lignified sclereids or stone cells occur in the cortex. They may appear elongated, U-shaped, or horseshoe-shaped in section.
Primary phloem
- Occurs as a narrow zone beneath the cortex.
- It may be crushed or compressed in older bark.
Secondary phloem
- Broad and made of phloem parenchyma, sieve elements, phloem fibres, and medullary rays.
- Sieve tubes are generally collapsed and arranged in tangential groups.
- Phloem parenchyma contains starch.
Phloem fibres
- Thick-walled and lignified.
- They occur in tangential bands or groups, often with about 4 to 5 fibres in a row.
Medullary rays
- Radial strips of parenchymatous cells.
- Usually 2 to 3 cells broad in Cassia cinnamon.
- They may contain starch.
Calcium oxalate crystals
- Needle-like crystals may occur in parenchymatous cells or near medullary rays.

Key T.S. diagnosis:
Cork + broad cortex + large sclereids + few oil cells + many starch grains + 2 to 3 layered medullary rays.

A comparative study reports that C. cassia has cork and cortex, large sclereids, relatively few oil cells, 2 to 3 layered medullary rays, and abundant starch grains, unlike C. verum, which has no cork, more oil cells, smaller sclereids, and fewer starch grains (comparative cinnamon microscopy).

B. Powder microscopical characters

When powdered Cassia cinnamon is mounted in chloral hydrate or examined after suitable staining, the following are observed:

Character	Description / identifying feature
Cork cells	Brown, polygonal or rectangular cells arranged compactly in surface view.
Sclereids / stone cells	Large, thick-walled, lignified cells with narrow lumen; irregular, elongated, horseshoe-shaped, or U-shaped. These are prominent diagnostic elements.
Phloem fibres	Long, lignified fibres with pointed ends, thick walls and narrow lumen; may show a slit-like central lumen.
Starch grains	Numerous, small, simple and compound starch grains in cortical, phloem, and ray parenchyma.
Oil cells / oil globules	Rounded or oval cells containing yellowish-brown volatile oil or free oil droplets.
Phloem parenchyma	Thin-walled, elongated or polygonal cells, often packed with minute starch grains.
Medullary-ray fragments	Rows of rectangular parenchymatous cells, usually 2 to 3 cells wide.
Vessels	Fragments of pitted, reticulate, or spiral vessels may be present.
Calcium oxalate	Occasional needle-shaped crystals, especially in association with parenchyma or ray tissues.

Important staining reactions

Phloroglucinol and concentrated HCl: sclereids and fibres stain pink to red due to lignin.
Iodine solution: starch grains stain blue.
Sudan III/IV: oil cells or oil droplets stain orange-red.

Conclusion / identification

Cassia cinnamon powder is identified chiefly by the combination of:

Brown cork fragments
Large lignified stone cells
Thick-walled phloem fibres
Abundant starch grains
Few volatile oil cells
Fragments of broad medullary rays

This combination differentiates Cassia cinnamon from Ceylon or true cinnamon, which generally has more oil cells, smaller sclereids, fewer starch grains, and no cork in the commercial bark.

This is a shared conversation. Sign in to Orris to start your own chat.