Morphological and histological characteristics of crude drugs

Morphological & histological
characteristics of crude drugs
Presented By :Mr. N. V. Thorat

Ergastic cell contents: Introduction
The cell contents, with which we are concerned in pharmacognosy are those
which can be identified in vegetable drugs by microscopical examination or by
chemical and physical tests.
These cell contents represent either food-storage products or by-products
of metabolism and include carbohydrates, proteins, fixed oils and fats,
alkaloids and purines, glycosides, volatile oils, gums and mucilages,
resins, tannins, calcium oxalate, calcium carbonate and silica; being
nonliving, they are referred lo as ergastic.
Ergastic substances are non-protoplasm materials found in cells.
Ergastic substances may appear in the protoplasm, in vacuoles, or in the cell
wall.
Volatile oils

Calcium oxalate crystals
Oxalic acid rarely occurs in the free state in plants but is extremely common as
its calcium salt in the from of crystals.
Oxalic Acid
Ca ++
Calcium oxalate
Formation of Crystals
Oxalic acid + Ca++ Calcium oxalate
Deposited in diffrent tissues,in diffrent forms
Harmless to plant
Does’n take part in metabolism hence called
excretary product
Calcium oxalate is usually present to the extent of about 1 % in plants but in
some structure such as the rhizome of rhubarb it may, exceed 20% of the dry
weight.
To remove
harmful effect
Obtained
from soil
Harmful to plant
Harmless
Protein metabolism
& Other metabolism

General form and size of the crystals
When calcium oxalate is present, it is important that the types of crystal,their size
and distribution be recorded.
The most common forms encountered are
Prisms Senna, hyoscyamus. quassia. liquorice. cascara, quillaia.
rauwolfia, calumba
Rosettes Rhubarb, stramonium, cascara, senna, clove, jalap
Single acicular crystals Ipecacuanha gentian. cinnanron
Bundles of acicular crystals Squill
Microsphenoidal / sandy crystals Belladonna
Cascara shows cluster crystals generally distributed in the ground mass of parenchyma
and prisms confined to the rows of parenchymatous cells forming a sheath
Fig: Calcium oxalate.A-Dcrystals of tetragonal
system ,E-I: Crystals of monoclinic system
A3:Rosette crystals as seen in A1 & A2 .D:A
tetragonal prism,G:raphides,H:A single
needles,

Fig: Calcium oxalate.A-D Crystals of tetragonal system ,E-I: Crystals of
monoclinic system A3:Rosette crystals as seen in A1 & A2 .D:A tetragonal

Chemical test / Detection
Sections + Chloral hydrate or caustic alkali (To clear Section).
Section + Acetic acid / Caustic alkali.
Insoluble calcium oxalate crystals
Calcium oxalate crystals + Hydrochloric acid
Soluble
Calcium oxalate crystals + 50% sulphuric acid
Needle-like crystals of calcium sulphate

Significance
They give protection to the plant against birds and animals.
They have great dignostic value.
Presence and absence of crystals ,type of crystals,dimenshions are useful in
correct identification of crude drugs.
Helps in detection of adultrants.
– e.g.In Java Cinnamon and Cassia bark tubelar calcium oxalate crystals are present in
the cells of medullry rays while they are not found in the medullary rays of Ceylon
cinnamon bark.
– Clove stalk contains calciun oxalate prisms but clove flower bud does not.
– In Jamaica quassia prisms are present in parenchyma while in Surinam quassia they
are not found.
– Leaves of plant of Solanaceae family types of calcium oxalate prisms.
They are absent in certain drugs like Digitalis leaves, Colocynth, Nutmeg,
Linseed and colchidum
Solanaceous leaves Types of Crystals
Belladona Microsphenoid
Hyoscymus Prism and square
Stramonium Cluster

It often forms a character of considerable diagnostic importance. The
solanaceous leaves may be distinguished from one another, belladonna by its
sandy crystals. Stramomium by its cluster crystals. and henbane by its single
and twin prisms. Similarly, phvtolacca leaves and roots, which both possess
acicular crystals, are distinguished from belladonna leaves and roots, which
have sandy crystals.

Starch grains
Starch constitutes the principal form of carbohydrate reserve in the green
plant and is to be found especially in seeds and underground organs.
Starch occurs in the form of granules (starch rains) the shape and size of which
are characteristic of the species as is also the ratio of the content of the principal
constituents, amylose and amylo pectin.
A number of starches are recognized for pharmaceutical use. They include maize
(Zea mays L.). rice (Oryza sativa L.), wheat (Triticum aestivum L.) and potato
(Solanum tuberosum L.) (EP, BP). Maize wheat and potato starches are official
in the USNF (1990).
Tapioca or cassava starch (Manihot utilissima) may be used in place of the above
in tropical and subtropical countries. The more important comrnercial starches are
listed in Table
Starch grains

Occurrence in plant
Starch occurs in granules of varying sizes in almost all organs of plants: it is
found most abundantly in roots, rhizomes, fruits and seeds. Where it usually
occurs in larger grains than are to be found in the chlorophvll containing
tissues of the same plant.
The small granules formed in chloroplasts by the condensation of sugars are
afterwords hydrolysed into sugars so that they may pass in solution to storage
organs where under the influence of leucoplasts large grains of reserve starch
are formed.
Description
Starch occurs as fine powder or irregular, angular masses readily reducible to
powder.
Colour Rice and maize starch grains are white, while wheat is
cream coloured and potato is slightly yellowish.
Odour Odourless
Taste Mucilaginous
Size and Shape Starch grains vary depending upon the types which can
be described as under.
Starch grains

Microscopic characters
1. Rice Starch : The granules are simple or compound. Simple granules are
polyhedral, 2 to 12 micron in diameter. Compound granules are ovoid and 12 to
30 µ ´ 7 to 12 µ in size. They may contain 2 to 150 components.
2. Wheat Starch : Simple lenticular granules which are circular or oval in shape and
5 to 50 µ in diameter. Granules contain hilum at the centre and concentric faintly
marked striations. Rarely, compound granules with 2 to 4 components are also
observed.
3. Maize Starch : Granules are polyhedral or rounded, 5 to 31 in diameter, with
distinct cavity in the centre or two to five rays cleft.## Fig. 7.12 : Commercial
Starches
4. Potato Starch : Generally, found in the form of simple granules, which are sub-
spherical, somewhat flattened irregularly ovoid in shape. Their sizes vary from
30 to 100µ. Hilum is present near the narrower end with well marked concentric
striations.
Starch is insoluble in cold water and also in alcohol.
Starch grains
No Type Shape Size
1 Rice
Starch
Simple-polyhedral
Compound-ovoid
Simple-2 to 12
micron in
diameter
Compound-12 to
30 µ ´ 7 to 12 µ
2 Wheat
Starch
Simple lenticular granules which are circular or oval
in shape .Granules contain hilum at the centre and
concentric faintly marked striations. Rarely,
compound granules with 2 to 4 components are also
observed
5 to 50 µ in
diameter.
3 Maize
Starch
Granules are polyhedral or rounded, with distinct
cavity in the centre or two to five rays cleft.
5 to 31 µ in
diameter,
4 Potato
Starch
Generally, found in the form of simple granules,
which are sub-spherical, somewhat flattened
irregularly ovoid in shape.. Hilum is present near the
narrower end with well marked concentric striations.
Their sizes vary
from 30 to 100µ

Chemical Constituents
Starch contains chemically two different polysaccharides viz. amylose (b-
amylose) and amylopectin (a-amylose), in the proportion of 1: 2.
Amylose is water soluble and amylopectin is water-insoluble, but swells in
water and is responsible for the gelatinising property of the starch.
Amylose gives blue colour with iodine, while amylopectin yields bluish black
colouration.
Identification
1. 1 g. of starch + 15 ml- of water Translucent viscous jelly
2. The above jelly + Iodine Deep blue.
Blue colour reappears on cooling.
Starch grains
Boil
Warm
Cool
Blue colour
dissappear
Cool

Uses
Starch is of considerable pharmaceutical importance .
Starch is used as a nutritive, demulcent, protective and as an absorbent.
Starch is used in the preparation of dusting talcum powder for application
over the skin.
It is used as antidote in iodine poisoning, as a disintegrating agent in pills
and tablets, and as diluent in dry extracts of crude drug.
It is a diagnostic aid in the identification of crude drugs.
Glycerin of starch is used as an emollient and as a base for suppositories.
Starch is also a starting material for the commercial manufacture of liquid
glucose, dextrose and dextrin. Starch is industrially used for the sizing of paper
and cloth.
Starch grains

Aleurone grains
Of the reserve food founds in seeds ,the most characteristic are protein
reserve which may be present as an amorphous mass completely filling the
cells in the endosperm of cardamoms or may take the form of definite grains
named aleurone grains.
Seeds are the only plant members in which aleurone grains occur hence a
powder containing these grains may be known to have derived from a seed.
The aleurone may be segregated in perticular tissue or part of tissue or it
may be distibuted throughout the tissues in association with other
reserves.
Aleurone grains are vary much in size ,shape and complexity.
They are frequently characteristic of perticular seeds or the seeds of
perticular familes of plants.
Many aleurone grains are small in size and very simple in structure. Such
grains consist of amorpous mass of protein enveloped by rather more dense
protein mambrane.This is type of grains found in many Leguminous seeds
(peas,beans etc) and in cereals.
Protein and aleurone grain are insoluble in ether,alcohol and glycerine; they are
stained yellow by solution of iodine.
Aleurone grains

Storage protein occurs in the form of aleurone glains which are particularly well
seen in oily seeds (e.g. Castor seed and linseed).
Often, however the ground mass of protein encloses one or more rounded
bodies or globoids and an angular body known as the crystalloid.
Aleurone grains are best observed after defatting and removal of starch, if
these are present in larre amount.
Sections being examined for aleurone should be treated with the following
reagents:
( l ) Millon's reaqent stains the protein red on warming,
(2) Iodine solution stains the ground substance and crystalloid yellowish-brown but
leaves the globoids unstained,
(3) Picric acid stains the ground substance and crystatlloid yellow.
The endosperm cells of nutmeg each contain one large and several smaller
aleurone grains. The large aleurone grains are 12-20 μm in diameter,and
contain a large well defined crystalloid.
Aleruone grains. containing globoids, are present in the endosperm and
cotyledons of linseed. Some of the aleurone grains of the endosperm of fennel
contain minute cluster crystal of calcium oxalate: others contain one or more
globoids.
Aleurone grains

Aleurone grains
Aleurone grain showing crystalloid and globoid from the endosperm of seed of Ricinus cimmunis

Idioblasts
Idioblasts are cells which differ markedly from ordinary cells of a tissue in
either form ,size or contents.Such cells are often present in the mesophyll
of leaves, in tea(Fig.) and hamamelis (Fig) peculiarly shaped,thickened and
strongly lignified idioblasts are occur and very characteristic of the powder
as well as whole leaf.
The cells containing calcium oxalate may differ frorn those surrounding
them in size. form or contents. And are often reffered to as idioblasts.
Idioblasts

In laurel leaf Laurus nobilis ,in boldo leaves Pneumus boldo ,and many
leaves of the piperaceae the idioblasts are large spherical cells filled with
volatile oil ;
In belladoona (Fig) one find large rounded idioblasts filled with
microsphenoidal crystals of calcium oxalate.
In some leaves such as stramonium and henbane ,the idioblasts containing
calcium oxalate crystals are arranged in single layer immediately
below palisade and constitute crystal layer iin the mesophill.(Fig)
Idioblasts

Study of morphology and histology barks
The bark consist of secondory external tissues lying outside the
cambium in stem or root of dicoteledonous plant are known as the bark.
In botany ,the bark consist of periderm and tissues lying outside it, i.e
cork phellogen and phelloderm.
Bark

A young bark (Fig.)is. composed of the following tissues.
(l) Epidermis:
A layer of closely fitting cuticularised cells with occasional stomata.
(2)Primary cortex:
A zone usually consisting of chlorophyll containing collenchyma and
parenchyma
(3) Endodermis: (or inner layer of the cortex)
Which frequently contains starch.
(4) Pericycle:
Which may composed of parenchyma or of fibres. Groups of fibres often
occur opposite each group of phloem.
(5) Phloem:
Which consist of sieve tubes, companion cells and phloem parenchyma
separated by radially, arranged medullary rays.
Bark

Bark
Fig, Stem structure of dicotyledons
(tronsverse section)
A. , primory structure showing seven
vascular
bundles;
B, development of complete combial ring
by formation of the interfascicular
cambium;
C, Beginning of secondary growth;
D, stem after a number of seasons of
growth, outer cork now present.
E-H,types of vascular bundle:
E-colloteral F-bicolloteral; G-amphivasal,
H-amphicribal., C-Cambium; c1-
fasciculor cambium c2 -interfascicular
cambium, ck-cork; ct, cortex en-
endodermis, ep- epidermis, g.r- growth
ring; pd- phelloderm pf- pericyclic fibres;
pg-phellogen , pg1-, developing
phellogen; pi-pith;r-rays; r1, primary
medullory ray;sc-sclerenchyma, xy-xylem
xy1, primary xylem; 1- phloem; 1a-
protophloem; 2- fascicular combium 3-
xylem3a-protoxylem

Method of collection of bark
Bark is generally collected in spring or early summer because the cambium is
very active and thin walled and gets detached easily .Following are the methods
of collection.
1.Felling method-The fully grown tree is cut down near the ground level by axe.
The bark is removed by making suitable longitudinal and transverse cuts on the
stem and branches .The disadvantage of these method are (a) the plant is fully
destroyed and (b)the root bark is not utilised
2.Uprooting method – The stem of definite age and diameter are cut down .The
root is dug up and bark is collected from the roots ,stems and branches .
In Java Cinchona bark is collected by this method.
3.Coppicing method – The plant is allowed to grow up to certain age and
diameter.The stems are cut at certain distance from ground level. Bark is
collected from stems and branches.The stumps remaining in the ground are
allowed to grow up certain level;again the shoots are cut to collect the bark in the
same manner.
Cascara bark and Ceylon cinnamon bark are collected by this method.
Bark

Barks may be described under the following headings:
Origin and preparation.
From trunk branches or roots. Whole or inner bark. Part used, genus, species & family.
Size and shape
Bark
Outer surface.
Lichens, mosses, lenticels(porous tissue consisting of
cells with large intercellular spaces in the periderm of the
secondarily thickened organs), cracks or furrows.
colour before and after scraping.
1- Cracks and fissures: arise owing to
continued increase in growth and to the lack
elasticity.
2- Wrinkles and furrows: The greater
shrinkage of the softer tissues result in
formation of wrinkles (because the shrinkage of
the barks during drying occur chiefly
transversely.
3- Smooth: when the cork is evenly developed
(or younger trees).
4- It may be scaly due to exfoliation of the
outer tissues

Inner surface
Colour, striations, furrows.
It is usually paler in color than outer surface and can be described as:
1- Smooth: due to the presence of uniform soft inner tissue
2- Striated Striated: when showing showing fine or coarse parallel
longitudinal ridges, produced as a result of transverse shrinkage
3- Corrugated: when showing transverse parallel wrinkles or folds produced
as a result of longitudinal shrinkage
Condition
fresh or dry; entire or broken pieces
Size
Measure height, width and thickness.
Bark

Fracture
“This term describes how the barks broken
transversely and the character of the broken surface.”
It is described as:
1- Short: When the fractured surface is smooth.
2- Splintery: When sharp and jagged projection are
formed. Splintery
3- Fibrous: When fine fibrous threads extend from the
broken surface.
4- Granular: When the surface exhibit small rounded
prominences.
5- Horny: When hard to broken and exhibiting hard
horn like broken surface.
6- Laminated: When breaks into arranged layers.
7- Flexible: When breaking only by tearing or twisting.
The fractrure depends largely on the number
and distribution of sclerids and fibres.
A bark frequently breaks with a short
fracture in the outer part and a fibrous fracture in
the phloem.
Bark

Touch
The park may be smooth or showing longitudinal or transverse furrows or
showing cracks or fissures.
Transverse surface
A smoothed transverse surface, especially if stained with phloroglucinol and
hydrochloric acid, will usually show the general arrangement of f the lignified
elements .medullaly rays and cork. Sections, however are more satisfactory and
can be used for a microscopical examination of calcium oxalate
Bark

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 from the plant
1- Flat: When derived from old trunk. It is
usually quite flat and very thick
2- Curved: When curved and slightly
concave on the inner side
3- Recurved: When the concave side is the
outer one
4- Channeled: When deeply concave on
the inner side.
5- Single quill: When deeply concave on
the inner side that the edges of the bark
nearly or quite overlap.
6- Double quill: When both edges are
separately in rolled
7- Compound quill: When single or double
quills are packed inside one another
Bark
3

• Histology of the bark
Bark

Monocot and Dicot
Based on the nature of embryo in the seed ,angiosperms (group of plant that
have flowers and produce seeds) are divided into dicots and monocots.
Dicotyledonae (Dicots ) consist of plant having seeds with two cotyledons and
the plant are called as dicotyledon plant.
Example : Mango,Neem.Sunflower, Tomatoes, Peppers, Apples, Carrots and
Celery.
Monocotyledonae (Monocots) consist of plant having seed with one cotyledon
and the plant are called as Monocotyledon plant
Example: Grassses,Sugercane,Maize and Wheat,, onion, Asparagus
Monocot and Dicot

Diffrence between monocotyledonous plants and dicotyledonous plant.
/ Monocot vs. Dicot
Monocots differ from dicots in distinct structural features: Seed, leaves, stems,
roots and flowers.
Seeds (Number of Cotyledons)
The actual basis for distinguishing the two classes of angiosperms is the number
of cotyledons found in the embryo, and is the Monocotyledonae (one cotyledon)
and Dicotyledonae (two cotyledons).
Roots: Fibrous vs. taproot
Once the embryo begins to grow its roots,
another structural difference occurs.
Monocots tend to have “fibrous roots”.
These fibrous roots occupy the upper
level of the soil in comparison to dicot
root structures that dig deeper and
create thicker systems.
Dicot roots also contain one main root
called the “ taproot ”, where other,
smaller roots branch off.
Monocot and Dicot

Stems: Arranging the vascular tissue
As the monocots develop, their stems arrange the vascular tissue complexly
arranged. This is extremely unique compared to dicots’ arranges the tissue into a
ring like structure.
.
Secondary Growth
Most dicots increase their diameter through secondary growth, producing
wood and bark.
Monocots (and some dicots) on the other hand have lost the ability of
secondary growth, and so do not produce wood. Some monocots can
produce a substitute however, as in the palms and agaves.
Monocot and Dicot

Leaves: Parallel veins vs. branching veins
The leaves of monocots are often long and narrow, with parallel veins.
Sometimes, the veins run from the centre of the leaf to the edge, parallel to one
another.
While dicots form “branching veins.”
Leaves of dicots come in many different shapes and sizes. The veins go from the
central midrib to the edge of the leaf, crossing and joining to form a netted pattern
all over the leaf.
.
Monocot and Dicot

Flowers: Number of Flower Parts
Monocot flowers tend to have a number of parts that is divisible by three,
usually three or six.
Dicot flowers on the other hand, tend to have parts in multiples of four or five.
Pollen Structure:
In the monocots, the pollen are characterized with a single furrow or pore
through the outer layer (monosulcate), but most dicots have descended from a
plant which developed three furrows or pores in its pollen (tri-porate).
Monocot and Dicot

GERMINATION
When a monocot seed germinates, it produces a single leaf. It is usually long
and narrow, like the adult leaf. Even when it is quite a round shape, there is
only one seed leaf in a monocot.
When a dicot germinates, it produces two seed leaves. They contain the food
for the new plant, so they are usually fatter than the true leaves. The first true
leaves are often a different shape
Monocot and Dicot

Monocotyledonous plant Dicotyledonous plant
Embryo/ Seed has single cotyledon. Embryo / Seed has two cotyledons.
Adventitious root system are present. Tap root system are present.
Leaves has parallel venation. Leaves has net venation or reticulate
venation.
Flowers usually incomplete and trimerous
(Floral part are in the number of threes).
Floers usually complete and pentamerous
(floral parts are in number of fives).
Vasculaer numbers in stem are numerous
and scatered.
Vasculaer numbers in stem are few and
arranged in circles or rings.
No cambium ,no secondary growth in
stem.
Cambium is present. Secondary growth
occure.
Stem uaually hollow. Stem uaually solid.
Seed germination normally hypogeal. Seed germination either hypogeal or epigeal.
Pollen with single furrow or pore. Pollen with three furrows or pores
Secondary growth absent. Secondary growth present.
Monocot and Dicot

LEAVES OR IEAFLETS
The following features can be used to describe leaves.
Duration
Deciduous or evergreen
Leaf base
Stipulate (outgrowths borne on either side (sometimes just one side) of the base of a leafstalk ) or
exstipulate, if stipulate describe shape etc:
if sheath is present describe it (e.g. Amplexicual –stem clasping).
(Leaf sheath-the leaf base when it forms a vertical coating surrounding the stem.)
Leaf

Leaf
Petiole.
Petiolate or sessile. If present
describe size,shape. colour. hairs
etc.
Lamina
( a ) Composition. lf simple,
wheaether pinnate or palmate.If
compound wheather paripinnate
(with an equal number of leallets) or
imparipinnate .
(b) Incision. The leaf may be more or less cleft.

(c) Shape.If the shape is obscured by drying, soak the leaf in water and
spread it on a tile. The appropriate terms connected with leaf shapes are
given in Fig. .
Leaf

(d)Venation.Parallel, pinnate (feather-like). Palmate, reticulute (net- veined).
(e) Margin. See Fig. for terminology.
(f) Apex. See Fig. fbr terminology.
(g) Base. Symmetrical or asymmetrical: cordate, reniform. etc.
(h)Surface
Colour
Glabrous (fee from hairs) or pubescent (hairy)
If the latter whether hispid (with rough hairs), hirsute (with long distinct
hairs) ol with glandular hairslpunctate (dotted with oil glands).
Note any differences between the upper and the lower surfaces.
(i) Texture Brittle, coriaceous, papery, fleshy, etc.
Leaf

Leaf
Fig:Transverse section of
senna leaflet
c- collenchyma
c.r -calcium oxalates crystals,
cr.s-crystal sheath
l.e-lower epidermis
l.p – lower palisade
m-mucilage cell;
ph-phloem
p.f-pericyclic fibre;
s-stomata
s.m.-spongy mesophyll
t- trichome
t.s.- trichome scar;
u.e-upper epidermis
u.p-Upper palisade
v.b-vascular bundle
x; y - xylem vessels

Anatomy
The leaf (Fig.) is built up of a protective epidermis, a parenchymatous mesophyll
and a vascular system.
Epidermis
The shape,size and wall structure of the epidermal cells.
The form, distribution and relation to the epidermal cells of the stomata
The form, distribution and abundance of epidermal trichomes are all of
diagnostic importance.
Mesophyll
The mesophyll may or may not be diflerentiated into spongy mesophyll and
palisade tissue.
Palisade tissue - may be present below both surfaces or occur only below
the upper epidemis.
In all green leaves the mesophyll cells are rich in chloroplasts.
The mesophyll although typicality parenchymatous may contain groups of
collenchyma or sclelenchyma, secretion ducts or latex tissues ,oil or
mucilage cells,or hydathodes (water pores).
Cells may contain inclusions such as crystals or calcium oxalate, the form,size
and distribution of which may have importance.
Leaf

The vascular systems
The vascular systems of leaves fall into two main classes the reticulate venation
typical of dicotyledons and the parallel venation of monocotyledons.
In leaves with a well differentiated midrib the palisade tissue is usually
interrupted in the midrib region and collenchyma frequently occurs a bove
and below the midrib bundle.
The xylem laces towards the upper surface
The development of the pericycle is variable in some cases being
parenchymatous and containing secretion cells, in some cases consisting of a
sheath of pericyclic fibres with their long axes parallel to the vein.
For the investigation of the structure of a leaf it is necessary to examine
transverse sections of the lamina and midrib; portions of the whole leaf. including
leaf margin, cleared in chloral hydrate; and surface preparations of both
epidermis sections should be cleared, if necessary, and stained for cellulose
and lignin. In individual cases it may be necessary to apply microchemical tests
for mucilage. Tannin,cutin. volatile oil, calcium oxalate or carbonate.
Leaf

Powdered leaves.
The following are consistently present:
epidermis with stomata
cellulose parenchyma: not very abundant
small sized vascular elements and chlorophyll (except in bulb leaves).
Structures frequently present are epidermal trichomes, glands, palisade
cells, crystals of calcium oxalate, collenchymas and pericyclic fibres .
For the differentiations of closely allied leaves it may be necessary to make
determinations of such differential characters as vein islet number stomatal
number, stomatal index and palisade ratio.
Leaf

Root
Root
Plant roots are structures specialized for anchorage, storage, absorption,
and conduction.
The roots are characterised by their downward growth (decending
part) into the soil. They do not have nodes and inter-nodes.
LOCATION- grows underground
TYPES OF ROOTS
1) Primary- formed directly from axis of embryo plant.
2) Lateral- arises from primary

Types
Fibrous root system
A diffuse or fibrous root system, found in most monocots, is very
fine, with lots of branches and usually is fairly shallow.
Taproot system
Common grasses and corn are examples of monocots. A taproot
system, found in most dicots, usually has a thick main root directly
under the stem and fine lateral roots that develop off of it.
Adventious roots
They develop from organs
Root

Morpholody
(1) Type / Kind.-True (i.e. developed from the radicle or its branches ) or
adventitious.
Tap root,Fibrous root, Adventitious root
(2) Size and shape. Tuberous,conical, cylindrical,etc.
(3) Surface characters. Colour; cracks. wrinkles, annulations. lenticels. etc.
(4) Fracture and texture.
(5) Transverse section. Note absence of pith, whether the wood is markedly
radiate or not, and any abnormalities such as are found in jalap and
senega.
Ashvagandha root Liquorice root
Root

Anatomy
The root is made up of three basic tissue
systems: epidermis, cortex, and vascular tissue.
Root

The primary root (Fig. A) shows the following strlrctlure
Epidermis
Piliferous layer composed of a single layer of thin-walled cells, devoid of cuticle
and bearing root hairs formed as lateral outgrowths of the cell
Root
Cortex
The parenchymatous cortex occupies the largest
area of most annual roots.
Endodermis
The innermost layer of the cortex consists of a
single layer of cells
Stele
(vascular cylinder or stele )
The stele is the innermost region of the root system
and contains the xylem, which transport water and
minerals from the roots to the shoots, and phloem,
which transport photosynthates from the shoot to
the roots
.Other charactristics - Medulary rays(Ipecac; Rouwolfia,Snega)
Starch-Ashvagandha

Stem
The stem is an ascending axis of the plant developed from the
plumule. It consists of nodes, internodes and buds and it gives rise to
branches, leaves and flowers.
The stem may be aerial, sub-aerial and underground.
Depending upon the presence of mechanical tissues, the stems
may be weak, herbaceous or woody.
1. Weak stems : When the stems are thin and long, they are
unable to stand erect, and hence may be one of the following types.
(a) Creepers or prostate stems : They grow flat on the ground
without roots. e.g. grasses, gokharu, etc.
(b) Climbers : These are too weak to stand alone. They climb
on the support with the help of tendrils, hooks, prickles or roots. e.g. Piper
betel, Piper longum, Gymnema.
(c) Twinners : These coil the support and grow further. They
are thin and wiry. e.g. Ipomoea and Phaseolus.
2. Herbaceous or woody stems : These are the normal stems
and may be soft or hard and woody. e.g. sunflower, sugarcane, ephedra, etc.
Stem

Morphology
Stem
Colour
Odour
Taste
Size
Shape
Surface-
Nodes
Internides
Scar
Lentices-
one of many raised pores
in the stem of a woody plant that
allows gas exchange between the
atmosphere and the internal tissues

Anatomy
The primary stem (Fig 42.1A) shows the following structure epidermis, cortex
,medullary rays, medulla and a vascular system
Epidermis
The epidermis is composed of a single layer of compactly arranged cells and bears
stomata.
Cortex
The cortex is usually parenchymatous, the outer layers of cells in aerial stems
containing chloroplasts. The layers of cortex cells immediately underlying the
epidermis may be collenchymatous, constituting a hypodermis.
Endodermis
The endodermisis usually not well-differentiated in aerial stems, although a layer of
cells containing starch (starch sheath) and corresponding in position to the
endodermis may be defined.
Underground stems often resemble roots in showing a more or less well-
differentiated endodermis with characteristic Casparian strips. The pericycle may
take the form of a complete or a discontinuous ring of fibres or may be
parenchymatous and ill-defined. Pericycle fibres may form a cap outside each
primary phloem group. The vascular bundles ofthe dictyostelea re usually collateral.
but are in some cases bicollateral (Cucurbitaceae, Solanaceae,Convolvulaceae
Stem

Stem
E, stem after a number of seasons of growth, outer cork now present.
ck-cork;
pg-phellogen ,
pd- phelloderm ,
sc-sclerenchyma ,
pf- pericyclic fibres;
ph- phloem;
c-cambium ,
xy-xylem,
r-medullory ray;
g.r.-growth rings,
xy1- primary xylem ,
pi-pith;
A, primory structure showing
seven vascular bundles;
B, development of complete
combium ring by formation of
the interfascicular cambium
ct, cortex , en- endodermis,
ep- epidermis,

FLOWER
The flower is a modified shoot meant for production of seeds. A typical flower
consists of four different circles (whorls) arranged in a definite manner. A flower
is built upon stem or pedicel with the enlarged end known as thalamus or
receptacle. The four whorls of the flowers are as follows.
1. Calyx : It is the outermost whorl of
flower and is generally green in colour.
The individual member of calyx is
called sepal.
2. Corolla : It is the second whorl of
flower and is either white or bright
coloured. Each member of corolla is
known as petal. The number of petals
varies with the type of flower.
3. Androecium : It is the third circle of flower and constitutes the male part. The
individual component is called as stamen & each stamen consists of filament,
anther and connective.
4. Gynoecium :This is the fourth circle of the flower & constitutes the female
part.Each component is known as carpel or pistil,made up of stigma,style & ovary
.
Flower
Receptacle - Thickened part of a stem (pedicel) from which the flower organs grow.

In pharmacognosy, the drugs to be studied as flowers are either entire flowers in
botanical sense or the inflorescence or single part of the flower, used
medicinally.
The following are few examples of different parts of flowers.
(i) Inflorescence
(a) Raceme Digitalis, mustard
(b) Panicle (compound raceme) Gold mohar
(c) Capitula (Head) Chamomile, arnica, artemisia,
Sunflower, pyrethrum
(d) Umbel Caraway, fennel
(e) Cymose Jasmine
(f ) Hypanthodium Fig
(ii) Stigmas Saffron
(iii) Corolla and stamens Elder flowers
(iv) Petals Rose, red poppy
(v) Flower buds Cloves
Flower

Anatomy
The flower stalk or pedicel has a stem structure and in the powdered form
exhibits the appropriate elements.
The bracts, (small leaf at the base of flower stalk) calyx and, to a lesser extent corolla
have a leaf structure and will yield such elements as epidermis with stomata,
glandular and covering hairs, mesophyll cells, oil glands and crystals.
The epidermal cells of the corolla often have a papillose or striated cuticle.
Delicate coloured fragments of the corolla can often be distinguished in coarsely
powdered drugs.
A characteristic papillose epidermis may sometimes be present on the stigmas
of the gynaecium.
Characteristic fragments of the anther wall are diagnostic of the presence of
flowers. Shape and wall structure of pollen grains.
With powdered flowers the pollen grains, portions of the fibrous layer of the anther
wall and the papillose epidermis of the stigmas are obvious features.
Flower

Microscopic characteristics of the flower
bud of Tussilago farfara L.
(Kuandonghua)
(1) pollen grain;
(2) epidermal cells of stigma;
(3) nonglandular hair;
(4) lobes of tubular salverform;
(5) epidermal cell of bract
Flower

FRUIT
Ovules of the flowers
The ovules of the flowers, after fertilization, are converted into seeds, whereas
the ovary wall develops further to form the protective covering over the seeds,
which is known as fruit.
In botany, this particular coating is also called pericarp.
Pericarp consists of three different layers.
1. Epicarp : It is the outermost coating of the pericarp and may be thin,
thick or woody.
2. Mesocarp : A layer in between epicarp and endocarp, usually pulpy or
made up of spongy parenchymatous tissue.
3. Endocarp : The innermost layer of the pericarp, may be thin, thick or
even woody.
Fruit
Fertilization Seeds
Ovary wall develops further to form the
protective covering over the seeds
Fruit

If the ovules do not fertilize, the seedless fruits are formed.
Depending upon the number of carpels present in the flowers, the fruits fall
into following categories :
1. Simple fruits,
2. Aggregate fruits, and
3. Compound fruits.
1. Simple fruits : These are formed from the single carpel or from
syncarpous gynoecium. Depending upon the mesocarp, whether it is dry or
fleshy, they are classified as dry fruits and fleshy fruits. Dry fruits are further
classified into dehiscent and indehiscent fruits.
2. Aggregate fruits : These fruits are formed from many carpels or
apocarpous gynoecium.
3. Compound fruits : In this particular case, many more flowers come
together and form the fruits.
Fruit

False fruits : Sometimes, apart from the ovary, the other floral parts like
thalamus, receptacle or calyx grow and form the part of the fruit and such a
fruit is known as false fruit or pseudocarp.
Following are few examples of pseudocarp in which other parts of the flower
forming important part of the fruits are shown in the bracket.
Strawberry (thalamus).
Cashew nut (Peduncle and thalamus).
Apple (thalamus).
Marking nut (peduncle).
Pharmaceutical fruits
Differ from botanical fruits, in the respect, that pharmaceutical fruits may or may
not contain all the three layers.
e.g. Lemon and orange consist of only epicarp, tamarind and bael consist
of mesocarp, while fennel and dill contain all the layers, enclosing seed.
Fruit

Morphology
Under the macroscopical evaluation of the fruits following characteristics are studied.
Colour
Odour
Taste
Size
Shape
Texture
Ridge –Primary ,Secondary
Fruit

Microscopy
The whole fruit consist of two zones ,namely pericarp and the seed or
sometimes three parts namely epicarp, mesocarp and endocarp.
Epidermis of epicarp is similar to that of leaves, and shows specialised
parenchymatous cells, sclerides,oil cell and vascular bundle .
In umbelliferrous fruits oil cell are present in mesocarp as vitae.in many cases,
the endocarp is oily in nature containing oil globules,aleurone grains and reserve
starch.
Fruit

• Care must be taken to distinguish seeds from fruits or parts of fruits containing a
single seed (e.g. mericarps of the Umbelliferae).
• The seed is attached to the placenta by a stalk or funicle.
• The hilum is the scar left on the seed where it separate from the stalk.
• The raphe is a ridge of fibrovascular tissue formed in more or less anatropous
ovules by the adhesion of funicle and testa.
• The micropyle is the opening in the seed coats which usually marks the position
of the radicle.
Fruit

. .
Seeds are characterised by the presence of three parts known as embryo,
endosperm and seed-coat.
Endosperm is the nutritive tissue nourishing the embryo.
Endosperm may or may not be present in the seeds. Therefore, seeds are
classified as follows :
1. Endospermic or albuminous seeds : A part of the endosperm remains
until the germination of seed and is partly absorbed by embryo. It shows distinct
presence of endosperm, e.g. colchicum, isapgol, linseed, nux-vomica,
strophanthus, etc.
2. Non-endospermic or exalbuminous seeds : During the development of
seed, the endosperm is fully absorbed by embryo and endosperm is not
represented in the natural seeds.
e.g. sunflower, tamarind, cotton, soyabean, etc.
3. Perispermic seeds : Herein, the nucleus develops to such an extent that it
forms a big storage tissue and seeds are found to contain embryo, endosperm,
perisperm, and seed coat. e.g. pepper, cardamom, nutmeg, etc.
Seed
Seeds are mature, fertilized ovules. Ovules are structures of seed plants containing the female
gametophyte with the egg cell, all being surrounded by the nucellus and 1-2 integuments. In
angiosperms (flowering plants) the double fertilization results in formation of the diploid embryo and
the triploid endosperm
SEED

SEED STRUCTURE
External
Seed coat (testa)
Hilum
Embryo
Cotyledon
Epicotyl / Hypocotyl
Pumule
Radical
Seed

• Seed coat (Testa)
The seed coat protects the embryo
Can be of varying thicknesses, depending on the seed type
• Hilum
Scar / mark at which the seed was attached via the funicul to the ovary tissue
This is the point of attachment of seed to stalk.
• Embryo
The embryo is what forms the new plant.
The mature embryo consists of
cotyledons (seed leaves),
hypocotyl (stem-like embryonic axis below the cotyledons),
radicle (embryonic root).
• Cotyledon
The cotyledon is the first leaf that germinates.
It is filled with stored food that the plant uses before it begins photosynthesis.
Some plants have 1 cotyledon (monocot) and some have 2 cotyledons (dicot).
Seed

• Epicotyl /Hypocotyl
The basis for the plant’s stem.
It is known as the epicotyl above the cotyledon and
a hypocotyl below the cotyledon.
These grow upward in response to light.
• Plumule
The shoot tip with a pair of miniature leaves.
• The Radicle
The part of the seed where the root develops.
Seed

• Raphe :
Raphe is described as longitudinal marking of
adherent stalk of anatropous ovule.
• Micropyle
It is the minute opening of the tubular structure,
wherefrom water is provided for the germination of seeds.
• Endosperm:
Food storage tissue
Seed

Special Structures :
In some instances, apart from regular growth of seeds, additional growth is visible in
the form of appendages.
1. Aril : Succulent growth from hilum covering the entire seeds, as
observed in nutmeg (mace).
2. Arillode : Outgrowth originating from micropyle and covering the
seeds, as seen in cardamom.
3. Arista (awn): Stiff-bristle-like appendage with many flowering glumes of
grasses, as found in strophanthus.
4. Caruncle : It is warty outgrowth from micropyle. e.g. castor, croton, viola.
5. Strophiole : Enlarged funicle. e.g. Datura fastuosa and colchicum seed.
6. Hairs : Gossypium and Calotropis are the examples of this type of
outgrowth.
These appendages are found to perform special functions, at times. For example,
hairs and awns of seeds help their dispersal.
Seed

The description of a seed may be arranged as follows:
Size, shape and colour, odour, and taste
Some features like funicle, raphe, hilium, and micropyle can be studied.
Hilum and micropyle-
Size and positions.
Seed coats-
Number, If present, describe arillode, caruncle or strophiole.
Thickness and texture of testa; whether uniform in colour or not:
Smooth, pitted or reticulate.
If hairs are present. describe their length. texture and arrangement
Perisperm - Present or absent Nature of food reserves.
Endosperm- Present or absent Nature of food reserves.
Embryo- Size and position (e.g. Straight in Strophanthus curved in stramonium).
Size, shape, number and venation of cotyledonsSize and shape
Seed

Anatomy
Embryo
The embryo is the fertilised ovule, an immature plant from which a new plant
will grow under proper conditions.
Endosperm
The stored food as a tissue called the endosperm, filled with proteinaceous
aleurone grains.
Seed coat
The seed coat helps protect the embryo from mechanical injury, predators and
drying out.
Seed

• The testas of seeds often yield highly diagnostic characters. A highly
diagnostics slerenchymatous layer is often present number of cell layers, and
their structure, arrangement, colour and cell contents subject to characteristic
variations
• The storage tissues perisperm and endosperm and in other case
cotyledons. are composed of uniform cells often containing characteristic cell
contents ( e.9.aleurone , starch, calcium oxalate,fixed oil, volatile oil. The cell
wall arc often considerably thickened (e.g. nux vomica).
Seed

WOODS
Wood consists of the secondary tissues produced by the cambium on its
inner surface .
Thus, it consists mainly of secondary xylem and smaller amount of other tissues.
The cells forming these tissues are highly lignified.
This central region is called the heartwood. while the outer wood, is called
sap wood.
Wood

Morphology
Woods may be described under the following headings.
Size and colour.
Note any differentiation into sapwood and heart wood. The latter may not be
coloured uniformly (e.g. logwood).
Relative density.
Woods vary considerably in this respect (e.g. guaiacum has a relative density of
1.33and poplar one of 0.38).
Hardness and behaviour when split
Wood

Anatomy
• ln transverse section woods usually show annual rings each of which normally
represents a season's growth.
• The width and height of medullary rays are of diagnostic importance
• The grain of wood primarily results fiom the arrangement of the annual rings
and medullary rays.
• Transverse surface, The lignified elements may show a markedly radiate
arrangement or they may be irregularly scattered.
• Note distribution of wood fibres and wood parenchyma and of true and false
annual rings. Measure the distances between medullary rays and between
annual rings.
• Longitudinal surfaces. Measure height of medullarly rays.
Wood

Rhizome
Rhizomes are modified stems found as an underground part of the plant. The
subterranean parts generally grow verically , horizantally or oblique direction from
the stem.
e.g. Ginger Rhubarb, Gentian,
Morphology
Rhizome may not look quite similar as similar as stem. The colour, odour, taste, size
and shape are general characteristic.
Rhizomes show presence of stem and scar (scars of fallen aerial leaves or root
scars and number of vegetative buds along with cracks ,wrinkles and lenticels. The
fracture may be hard ,flexible, horny or splintery.
They are thick, fleshy and are charactrised by presence of nodes and internodes and
scale leaves, e.g. Ginger, turmeric, Rhubarb
Rhizome

Microscopy
As rhizome is modified stem ,transverse section shows the presence of central
pith along with bark and wood in case of secondary growth. The presence of
secondary and primary vascular elements of xylem and phloem may be noted.
Larger and smaller zones of central pith indicate its relativity to stem.
Monocot rhizome shows the cork, outer cortex and inner cortex, seperated by
endo-dermis .Monocot rhizomes also shows scattered vascular bundles
throughout the inner cortical region.Cork and outer cortex is sometimes absent in
the peeled rhizomes.Dicotyledon rhizome shows circular vascular bundle and a
central pith.
In rhizome ,the transverse surface never shows a central solid mass of xylem, a
usefull character which helps to distinguish rhizomes from roots.
Rhizome

Mountants
• These reagents are used to mount the tissues or section and to prevent the
drying of sections. e.g. Glycerin or mixture of glycerin and water.
• Mounting media are needed for making permanent slides.
• The mounting medium holds the specimens in place between the cover
slip and the slide.
• Generally, mounting media for permanent slides can be categorized into water-
based and organic solvent based mounting media.
• While many water-based mounting media for permanent slides solidify and
hold the specimen firmly in place, some others remain in a liquid state. In this
latter case, it is necessary to prevent the liquid from flowing out by sealing the
four sides of the cover slip. Nail polish can be used for this.
Mountants

Properties of an Ideal Mounting Media (Mountant)
• Refractive Index I should be as close as possible to that of glass, i.e., 1.5.
• It should be colorless and transparent.
• It should not cause stain to diffuse or fade.
• It should be dry to a non-stick consistency and harden relatively quickly.
• It should not shrink back from the edge of cover-glass.
• It should have no adverse effect on tissue components.
• It should be resistant to contamination (particularly microorganism growth).
• It should protect the section from physical damage and chemical activity
(oxidation and changes in pH).
• It should be completely miscible with dehydrant or clearing agent.
• It should set without crystallizing, cracking or shrinking (or otherwise deform
the material being mounted) and not react with, leach or induce fading in stains
and reaction products (including those from enzyme histochemical, hybridization,
and immunohistochemical procedures).
• Finally, once set, the mountant should remain stable (in terms of the features
listed above).
Mountants

Classification of Mounting Media
1. Resinous (hydrophobic/adhesives/organic/non-aqueous)
2. Aqueous media (hydrophilic/non-adhesive)
Resinous/non-aqueous/adhesive media
• These are natural or synthetic resins dissolved in benzene, toluene or xylene and are
used when a permanent mount is required and frequently used in routine H and E
staining procedures.
• In general, adhesives harden through solvent evaporation and thereby fix the
accompanying cover slip to the slide. During this process the RI of the medium alters,
moving away from that of the solvent and toward that of the dry mountant.
Natural resinous media
• Canada balsam (RI = 1.52-1.54) • Phenol balsam (variant of Canada balsam)
• Dammar balsam (RI = 1.52-1.54) • Euparal (RI = 1.48).
Synthetic resinous media
The most commonly used are the polyesterenes, such as Kirkpatrick & Lendrum’s
mountant and Gurr’s distrene plasticizer xylene (DePex). 1. DPX (DePeX [Distrene 80: A
commercial polystyrene, a plasticizer, e.g., dibutyl phthalate and xylene]) (RI = 1.52) 2.
Histomount (RI = 1.49-1.50) 3. Cover bond (RI = I.53) 4. Gurr’s neutral mounting medium
(RI =1.51) 5. Histoclad (RI = 1.54) 6. Permount (RI = 1.526) 7. Pro-texx (RI = 1.495) 8.
Technicon Resin (RI = 1.62) 9. Uv-inert (RI = 1.517) 10. XAM (RI = 1.52).[
Mountants

Aqueous Mounting Media
• Aqueous mounting medium are used for mounting sections from distilled water
when the stains would be decolorized or removed by alcohol and xylene as
would be the case with most of the fat stains (Sudan methods). These media are
of three types: The syrups, Gelatin media, and Gum Arabic media.[5]
• Some of the metachromatic stains tend to diffuse from the sections into
mounting media shortly after mounting: this may be prevented by using fructose
syrup. Gome stains, e.g., methyl violent tend to diffuse into medium after
mounting. This can be avoided by using Highman’s medium. Aqueous mounting
media require the addition of bacteriostatic agents such as phenol, crystal of
thymol or sodium merthiolate to prevent the growth of fungi.
• 1. Water (RI = 1.333). 2. Glycerine jelly (RI = 1.47). 3. Glycerine-Glycerol (RI =
1.47). 4. Apathy’s medium (RI = 1.52). 5. Farrant’s medium (RI = 1.43). 6.
Highman’s medium (RI = 1.52). 7. Fructose syrup (RI = 1.47). 8. Polyvinyl
alcohol.
Mountants

Different types of mounting media.
• Water-insoluble mounting media that solidify
Euparal
It contains the substances sandarac, eucalyptol, paraldehyde, camphor, and
phenyl salicylate. Euparal possesses a nice odor due to the natural oils that are
included. Euparal is commonly used to mount histological specimens and insects.
One big advantage of Euparal is, that the specimens can be transferred directly
from the alcohol in which they are stored. Do not embed specimens which contain
water, this may result in a clouding of the mounting medium.
• Canada Balsam: The optical properties are nearly identical with those of glass.
For this reason, Canada Balsam was used for many years as a kit to hold optical
lenses in place. Canada Balsam has the advantage that its optical properties do
not deteriorate with age. Permanent slides mounted with Canada Balsam have
been stored for a century and are still useful.
The disadvantage of Canada balsam is, that the specimen must be placed into
xylene (toxic) before embedding. Wet specimens must first be dehydrated in
alcohol and then transferred to xylene. Transferring specimens directly from
alcohol to Canada balsam won’t work, because the alcohol won’t dissolve the
Canada balsam.
Mountants

• Eukitt and other resin-based media: Eukitt is a very fast drying general-purpose
resin-based mounting medium. Eukitt will solidify within about 20 minutes. The
specimens must be free of water and placed first in alcohol and then in xylene
prior to mounting. The use of xylene is a disadvantage, as it is harmful when
inhaled. Eukitt itself can also be diluted by xylene to adjust it viscosity.
Besides Eukitt, a range of other resin-based mounting media are commercially
available, such as Diatex, Entellan, Malinol, Rhenohistol and Depex. They differ in
their refractive index. All of these mounting media require the specimen to be first
dehydrated in alcohol and then transferred to xylene. Some of these resins shrink
significantly during the drying process.
• Clear nail polish: Nail polish can be used to seal the sides of the coverslip when
using aqueous mounting media. It can also be used directly as a mounting
medium. The specimens must first be dehydrated in alcohol and can then be
directly mounted (without xylene) in nail polish.
The advantage of nail polish is, that it is readily available and that it avoids the use
of toxic organic solvents to treat the specimens. One disadvantage is, that it
seems to shrink a lot when making very thick mounts
Mountants

• Water-insoluble mounting media that remain liquid
Various oils (immersion oil and paraffin oil) use as a mounting medium, they are
generally not used to make permanent slides. The specimen must be dehydrated
with alcohol and then transferred to xylene so that the liquid mounting medium (the
oil) is able to reach all the parts of the specimen.
• Water-soluble mounting media that solidify
Glycerol jelly: This is a water-based (aqueous) mounting medium. The handling of
this mounting medium, is also not too easy. The bottle with the solid glycerol jelly
must first be warmed in a water bath to make it liquid. Do not make it too hot,
otherwise it will not solidify any more. The specimen is submerged in the warm jelly
and the cover glass is placed on top. Bubbles are a problem with this medium. The
edges of the cover glass now must be sealed with nail polish to prevent drying out.
Glycerol jelly is one of the most difficult mounting mediums to use, but sometimes
there is no other satisfactory alternative to an aqueous mounting medium.
• Water-soluble mounting media that remain liquid
Glycerol: It is possible to make a permanent mounts by embedding the specimen
either in pure liquid glycerol or a specified glycerol-water mixture. The glycerol-water
mixture can be adjusted to an appropriate refractive index.
Mountants

Clearing agents
A substance that increases the transparency of tissues prepared for microscopic
examination.
These agent remove cell content such as starch protein resin volatile
oil,chlorophyll etc. which obsecure other more important characteristics of cell
structure.
Clearing may be done by mixing, shaking, washing or boiling with the reagents.
Removal of such cell contents make remaining part more transparent and reveal
details of the other characteristics.
The sections or the powdered drug samples are cleared by clearing agents,
mostly by chloral hydrate solution, before mounting on the slide
Clearing Agents

Clearing Reagents Merits & Demerits
Chloral hydrate solution
Chloral hydrate + Water (5:2)
Removes many common cell contents including chlorophyll
No marked distoration of tissues.
Very useful mountant for calsium oxalate crystal ,as it attack
them very slowly (about 20 days for complete dissolution)
Induce reswelling of cell walls.
On heating tends to crystallise( for prevention add 1-2 drops of
glycerine)
Oily clearing agent
i)Cedar wood oil
ii)Clove oil
Dissolve fixed oil
Use for preparation of permament mount.
Great penetration power
No swelling of tissues, some time cause shrinkage
Phenolic clearing agent
(alone or in combination)
Cresol
Lactophenol
Removes many common cell content
Make the starch almost transperant
Usefull mountant for Nux vomica hairs, chalk, kieaselguhr
,pollens etc.
Does not tend to crystallise
Usefull for mounting silk aloes ,etc
Does not tend to crystallise
Clearing Agents

Clearing Reagents Merits & Demerits
Sodium hydroxide and potassium
hydroxide solution
Removes starch and protein
Disintegrates certain cellulose tissues
Cause distortion of cell wall
Hydrochloric acid(20% v/v) Removes starch on hydrolysis on
boiling
Organic solvents
Lipid solvents like ether, pet, ether etc
Removes foxed oil,fats
Clearing Agents

Micro chemical reagents
The tests are carried out on section or powder of the drugs with small quantity of
reagents (e.gPhloroglycenol + Conc. Hcl (1:1) colour change (Pink ) is observed
with the microscope.
Micro chemical reagents
Name of Reagent Component 0 bservation
Eosin Cellulose Red Or Pink Colour
Conc. Sulphuric Acid + Iodine Colour Pale Blue Colour
Phloroglycenol + Conc.Hcl (1:1) Lignin Red Or Pink Colour
Safranin Lignin Red Or Pink Colour
Rheuthenium Red Mucilage Red Or Pink Colour
Alcoholic Picric Acid Protein Yellow Colour
Sudan Red -III Vol.oil Fixed Oils And
Fats
Yellowish Brown Colour
Dilute Iodine Starch Deep I Pale Blue
Conc. Sulphuric Acid Saponins /Stone Cells Green Colour
Ferric Chloride Tannins Blue I Black Colour

DIGITALIS
Synonyms
Digitalis leaves, Foxglove leaves.
Biological Source
Digitalis consists of dried leaves of Digitalis purpurea, family
Scrophulariaceae,
Morphological & microscopic difference

Macroscopic Characters
Colour - Dark greyish-green
Odour - Slight
Taste - Bitter
Size - 10 to 40 cm long and 4 to 20 cm wide
Shape - Ovate-lanceolate to broadly ovate; with irregularly
crenate or serrate or occasionally dentate margin.
Extra features
The leaves are slightly pubescent on both the surfaces with pinnate venation and
prominent veinlets on the under surface. Generally, the leaves are broken and
crumpled.

Microscopic Characters
Digitalis is a dorsiventral leaf. It has anomocytic stomata on both surfaces and
water pores at the apex of most of the marginal teeth. The trichomes are
uniseriate, multicellular (3 to 5 cells) and bluntly pointed. There are also
glandular trichomes with unicellular stalk and unicellular or bicellular head. The
glandular trichomes are generally located over the veins. Collapsed celled
covering trichome is an important characteristics of digitalis. Digitalis is
free of calcium oxalate and sclerenchyma. Starch grains are present in the
endodermis. There is collenchyma at 3 different places i.e. at the upper
epidermis, lower epidermis, and pericyclic part, which is also characteristic to
digitalis.
Steriodal and Triterpenoidal drugs

. DIGITALIS LANATA
Synonyms
Woolly fox glove leaf, Austrial Digitalis.
Biological Source
These are the dried leaves of Digitalis lanata Ehrhart, belonging to family
Scrophulariaceae,

The leaves are oblong, lanceolate, sessile
with entire margin. It is about 21 cm in length
and 6 cm in width.
The plant is a biennial herb about 1 meter in
height.

Microscopy
1. Upper epidermis:
Single layered, covered with a thick cuticle, cells have wavy and thick walls;
two kinds of trichomes are seen, multicellular, uniseriate covering trichomes and
glandular trichomes with unicellular stalk. Stomata are also seen occasionally
on the upper epidermis.
2. Mesophyll:
It is differentiated into palisade and spongy parenchyma. Calcium oxalate
crystals are absent.
3. Palisade:
Two layered, loosely arranged and does not form a continuous band
throughout as it is absent above the vascular bundles of lamina.
4. Spongy parenchyma:
Many layered and shows distinct transversely cut vascular bundles as in the
midrib.
5. Lower epidermis:
Identical to upper epidermis but numerous stomata

6. Midrib:
The dorsal surface of the midrib is strongly convex and as usual the
epidermis layers of lamina are in continuity with that of midrib but the cells of the
latter are smaller in size. Below the upper epidermis and above the lower
epidermis are seen thin strips of collenchymas. Rest of the midrib is filled
with cortical parenchyma.
An are shaped vascular bundle is present more towards the ventral surface
(upper epidermis) of the midrib. The vascular bundle is surrounded by distinct
endodermal layer, the cells of which contain abundant starch. Distinct phloem
tissue can be seen on the dorsal surface and well developed xylem tissue
towards the ventral surface of the midrib is seen thin.

BACOPA / JALBRAHMI
Synonym
BRAHMI
Biological Source
It consists of the fresh leaves and the stems of the plant known as Bacopa
moniera Linn. (Herpestis moniera), belonging to family Scrophulariaceae.
Geographical Source
It is a prostrate, succulent herb found throughout India, in wet, damp and marshy
places, upto 1200 m elevation.

Colour - Green
Taste - Bitter
Size - (Leaves) About 2 cm
Shape - The leaves are fleshy obovate, alternate, simple, entire,
with broad apex,sessile and their lower surface is dotted.

Hydrocotyle / BRAHMI
Synonym
Mandukparni
Biological source
It is the herb of Centella asiatica (Hydrocotyl asiatica), belonging to family
Umbelliferae (Apiaceae).
Geographical source
Mandukparni grows in wet areas in India, Sri Lanka, Pakistan, Indonesia and
Madasgascar, Africa, Australia, China and Viet-nam, upto an altitude of 650 m.

Colour – Greyish green
Odour – Characteristic
Taste – Bittersweet
It is also a creeping plant, but the leaves are bigger and long petiolate. The leaves
are entire, crenate, orbicular and reniform. Leaves are 1.5-6.5 cm in diameter,
petioles 7.5-15 cm in length, stipules are short forming sheathing base. It bears an
umbel inflorescence with 3 - 4 pink sessile flowers. The stems are red and show
long internodes. Like Jalbrahmi, rooting occurs at nodes.

CINNAMON
Synonyms
Cinnamon bark; Kalmi-Dalchini, Ceylon cinnamon , Sri Lanka cinnamon
Biological Source
Cinnamon consists of the dried inner bark of the shoots of coppiced trees of
Cinnamomum zeylanicum Nees., (Syn. Cinnamomum verum J. S. Presl)
belonging to family Lauraceae. It should not contain less than 1.0% of volatile oil.
.

Colour - Outer surface Dull yellowish-brown,
Inner surface Dark yellowish-brown.
Odour - Fragrant
Shape - Found in the form of compound quills.
Size - About 1 m in length and 1 cm in diameter. The thickness
of the bark is approximately 0.5 mm.
Taste - Aromatic and sweet followed by warm sensation.
Fracture - Splintery
The outer surface of the bark is marked by wavy longitudinal striations with small
holes of scars left by the branches. The inner surfaces also shows the
longitudinal striations. Bark is free of cork.

Substitutes and Adulterants
Jungle cinnamon : It is the bark obtained from wild growing trees, which is dark
in colour, less aromatic than the cultivated trees, and slightly bitter.
Cinnamon chips : These are pieces of untrimmed bark. They can be
distinguished from genuine drug by the presence of abundant cork cells and
by poor yield to 90% alcohol.
Saigon cinnamon : It consists of the bark of the trees of Cinnamomum loureirii
(Lauraceae). It is exported from the port of Saigon. It is also grown in China and
Japan. The bark is greyish-brown in colour with light patches and sweet taste.
Quills are 30 ´ 4 ´ 0.7 cm, unpeeled and contain 2.5% of volatile oil.
Java Cinnamon : It is derived from Cinnamomum burmanii (Lauraceae). Bark is
less aromatic, peeled and found in the form of double quills. Histologically,
medullary rays contain small tubular crystals of calcium oxalate, not found
in C. zeylanicum. It contains about 75% of cinnamaldehyde in the oil. It also gives
poor yield to 90% alcohol as compared to Sri Lanka cinnamon.

Tinospora
Biological Source
The genus Tinospora Miers (Menispermaceae) has about 32 species distributed
in tropical Africa, Madagascar, Asia to Australia and the Pacific Islands .
In India, the genus is represented by four species; two species, T. cordifolia
(Thunb.) Miers and T. sinensis (Lour.) Merr, are known to occur in South India
and other two T. Crispa (L.) Hook.f. & Thomson and T. glabra (Burm.f.) Merr, are
reported from Northeast India and the Andaman Islands.
In T. cordifolia the sclerenchymatous sheath becomes disintegrated into
scattered irregular patches in the cortical regions whereas in T. sinensis it is
broken into areas ,capping the vascular bundle and remains persistent even
after further secondary growth.
Crystals are absent in T. cordifolia while in T. sinensis a large crystal of
calcium oxalate is present within the lumen of each cork cell.
Mucilaginous cells are more in T. cordifolia as compared to T. sinensis.

Vascular strands are fewer in T. cordifolia while greater in T. sinensis.
Xylem is well developed in each strip of vascular strand in T. cordifolia while it
is poorly developed in T. sinensis.
Pith is very narrow and composed of thin walled cells in T. cordifolia while it is
wide in T. sinensis.
Starch content is more in T. cordifolia as compared to T. Sinensis.

Morphological and histological characteristics of crude drugs

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Morphological and histological characteristics of crude drugs