PLANT

MORPHOLOGY
 INTRODUCTION
• Plant morphology deals with the study of forms and features
of different plant organs like roots, stems, leaves, flowers,
seeds, fruits etc.
• Most of the drugs in ancient times were derived from plants.
• Almost all parts of the plants are used i.e. leaves, stem, bark,
fruits and roots.
PLANT SYSTEM
The body of a typical angiospermic
plant is differentiated into an:
• underground root system
• aerial shoot system
The shoot system consists of stem
(including branches), leaves, flowers
and fruits.
The roots, stems and leaves are
vegetative parts, while flowers
constitute the reproductive part.
 ROOT
The primary root, or radicle, is the first organ to appear when
a seed germinates. It grows downward into the soil,
anchoring the seedling.

Roots are generally positively geotropic (grow toward gravity),

positively hydrotropic (grow toward water), and negatively
phototropic (grow away from light).
 GROWTH IN ROOT
• Root Cap
• Apical Meristem
• Region of Elongation
• Region of Maturation
 PLANT TISSUES
• The primary tissues of
the root are, from
outermost to
innermost, the
epidermis, the cortex,
and the vascular
cylinder.
 THE EPIDERMIS
• The epidermis is composed of thin-walled cells and is usually only one
cell layer thick.
• The absorption of water and dissolved minerals occurs through the
epidermis, a process greatly enhanced in most land plants by the
presence of root hairs—slender, tubular extensions of the epidermal
cell wall that are found only in the region of maturation.
• The absorption of water is chiefly via osmosis, which occurs because
1. water is present in higher concentrations in the soil than within the
epidermal cells (where it contains salts, sugars, and other dissolved
organic products).
2. the membrane of the epidermal cells is permeable to water but not to
many of the substances dissolved in the internal fluid.
 CORTEX
• The cortex conducts water and dissolved minerals across the root
from the epidermis to the vascular cylinder, whence it is
transported to the rest of the plant.
• The cortex also stores food transported downward from the leaves
through the vascular tissues.
• The innermost layer of the cortex usually consists of a tightly
packed layer of cells, called the endodermis, which regulates the
flow of materials between the cortex and the vascular tissues.
 VASCULAR CYLINDER
• The vascular cylinder is interior to the endodermis and is
surrounded by the pericycle, a layer of cells that gives rise to
branch roots.
• Theconductive tissues of the vascular cylinder are usually
arranged in a star-shaped pattern.
• Thexylem tissue, which carries water and dissolved minerals,
comprises the core of the star; the phloem tissue, which carries
food, is located in small groups between the points of the star.
 TYPES OF ROOT SYSTEMS
• Tap Root System
• Fibrous Root System
• Adventitious Root System
 ROOT MODIFICATION
1. Modified tap root for storage
• Fusiformroots - swollen in middle, tapering toward both ends, i.e., top
and bottom. eg Radish
• Conicalroots - base is broad and tapers gradually and steadily toward
the apex. eg Carrot
• Napiform - spherical at base, tapering sharply like a tail toward the tip,
has top-like appearance. eg Sugarbeet
• Tuberous roots - thick and fleshy with no definite shape eg Mirabilis
2. Nodulated root: Nodules are formed on branches of roots by nitrogen
fixing bacteria, (Rhizobium). eg. Plants of leguminosae family
(Papilionatae) – Pea
 ROOT MODIFICATION
• 3.
Pneumatophores or Respiratory roots - some roots grow
vertically up (negatively geotropic) into air. Exposed root tip
possesses minute pores through which roots respire and
appear like conical spikes coming out of water. eg.
Rhizophora, Heritiera, Sonaratia and other mangrove plant.
 ROOT MODIFICATION
• Modification of adventitious roots:
1. Storage adventitious roots
 Tuberous root - swollen roots developing from nodes of prostrate
stem eg. Sweet potato (Ipomea batata)
 Fasciculated - swollen roots developing in a cluster from the stem
eg. Dahlia, Asparagus
 Nodulose - only apices of roots become swollen like single beads
eg. Melilotus, Curcuma amoda.
 ROOT MODIFICATION
 Beaded or moniliform - roots alternately swollen and constricted,
presenting a beaded or moniliform appearance eg. Vitis, Momordica
(Bitter gourd), Portulaca
 Annulated: Look as if formed by a number of discs placed one above
the other eg. Psychrotia, ipecac.
 ROOT MODIFICATION
2. Stilt roots or brace roots: extra roots developing from nodes near
the base of stem grow obliquely and penetrate the soil giving strong
anchorage eg. Maize, Sugarcane, Pandanus (screwpine)
3. Prop root or pillar roots: roots develop from tree branches, hang
downward, and ultimately penetrate the ground, thus support heavy
branches eg. Banyan.
4. Butteress root - such roots appear from the basal part of stem and
spread in different directions in the soil. – eg. Ficus, Bombax,
Terminalia. It is a characteristic feature of tropical rain forest.
 ROOT MODIFICATION
5. Climbing roots - weak climbers twine around and clasp the
support with the help of climbing roots arising from their nodes
– eg. Money plant (Pothos), Betel, Black pepper, Techoma.
6. Foliar roots or Epiphyllous roots - aerial roots of epiphytes are
greenish and covered with spongy tissue (velamen) with which they
absorb atmospheric moisture – eg. Bryophyllum, Bignonia.
7. Sucking or haustorial roots or Parasitic roots: parasitic plants
give out sucking roots or haustoria which penetrate living host plant
and suck food. eg. Dendrophthoe, Cuscuta, Viscum.
 FUNCTIONS OF ROOTS
The main functions of the root system include:
• Absorption of water and minerals from the soil
• Providing a proper anchorage to the plant parts
• Storing reserve food material
• Synthesis of plant growth regulators
• Conduction of water
• Photosynthesis and respiration
 APPLICATION IN
PHARMACOGNOSY
• Bioactivecompounds obtained from plant roots and tubers
demonstrate health benefits presenting antioxidative,
antimicrobial, hypoglycaemic, hypocholesterolaemic, and
immunomodulatory properties.
• Roots of many medicinal plants have been used for the
treatment of disease and formulation of drugs, and they are
also known for their commercial value, being used as an
ingredient in the pharmaceutical and cosmetic industries.
 ROOTS OF MEDICINAL
IMPORTANCE
• Medicinal plants having the active compounds like glycosides,
alkaloids, terpenoids, flavonoids, etc., are the potential
hyperglycemic agents. Medicinal plants having hyperglycemic
agents can be used as potential antidiabetic agents as these are
less toxic and free from side effects.
• Desmodium gangeticum is extensively used in Ayurveda for the
treatment of various diseases like typhoid fever, urinary
discharges, piles, and inflammations. It is also used in the
treatment of ischemic heart disease in Indian system of
medicine.
• Raphanus sativus also known as Radish is considered to be
an antiseptic, antirheumatic, appetite stimulant, diuretic,
diaphoretic, and rubefacient. Radish is an excellent source
of vitamin C and a powerful immune booster. It is used for
the treatment of gastrointestinal and cardiovascular
disorders. It is also used in inflammations, hiccough, leprosy,
and cholera too
 STEM
• Thestem is the ascending part of the axis bearing branches,
leaves, flowers and fruits.
• It
develops from the plumule of the embryo of a germinating
seed. The stem bears nodes and internodes.
• The region of the stem where leaves, branches, flower bud,
and bracts are born are called nodes while internodes are
the portions between two nodes.
• The stem bears buds, which may be terminal or axillary.
 STRUCTURE OF A STEM
• Internally,
it contains three basic types of tissues: Dermal
tissue, Ground tissue, and Vascular tissue all of which are
made of simple cells.
 STRUCTURE OF A STEM
• Epidermis: The epidermis is a single layer of cells that
make up the external tissue of the stem called dermal tissue.
This tissue covers the stem and protects the underlying
tissue. Woody plants have an extra layer of protection on
top of the epidermis known as bark.
• Ground tissue is divides into two- the central portion is
known as the pith and the cortex which lies between the
vascular tissue and the epidermis.
 STRUCTURE OF A STEM
• The cortex can be further divided into three layers:
• Hypodermis: It is the outermost layer of the cortex. It is formed of 4
to 5 cell thick layer of collenchymatous cells. These cells are living
and contain chloroplasts.
• Generalcortex: Lies below the hypodermis. It consists of thin-walled
parenchymatous cells with intercellular spaces. Some of the cells
have chloroplasts and are known as chlorenchyma.
• Endodermis: The innermost layer of the cortex. It is made up of a
single row of compact barrel-shaped cells without intercellular spaces.
The cells of endodermis store starch grains and so they are known as
the starch sheath. Casparian strips are distinctly visible in
endodermal cells.
 STRUCTURE OF A STEM
• The vascular tissue of the stem consists of the complex
tissues xylem and phloem which carry water and nutrients
up and down the length of the stem and are arranged in
distinct strands called vascular bundles.
• Cambium is a strip of thin-walled cells that lie between the
xylem and phloem in dicot plants.
• Cambium is made up of merismatic cells and is responsible
for secondary growth. It is absent in monocots.
 GROWTH IN A STEM
• Growth in stems occurs in two ways:
• Primary growth occurs at the apical tips of the stem by
virtue of the rapidly dividing merismatic tissue in these
regions of the stem.
• Secondary growth is actually the increase in the thickness
of the stem by virtue of the lateral meristems. These are
absent in the herbaceous plants as they lack cambium
which is responsible for this type of growth.
 TYPES OF STEM
• Aerial stem
• Subaerial stem
• Underground stem
 AERIAL STEM
These stems are found above the ground and perform varied
functions.
• Reduced – Stem reduced to a disc. eg., Radish, Carrot, Turnip.
• Erect stem - It is strong and upright e.g., maize, wheat, mango.
• Weak stems – These are thin, soft and weak and need support.
They can be upright or prostrate.
 WEAK STEMS
• Creepers– The stem creeps on earth and the roots arise at the
nodes, e.g., Grasses, Strawberry, Oxalis.
• Lianas(Stem climber) - They twin themselves around tall trees to
secure sunlight, e.g., Hiptage, Bauhinia vahlii (Phanera).
• Climbers – Plants are with long weak stem and have organs of
attachment to climb the object. Eg. Rootlet climbers, Hook climbers,
Tendril Climbers.
• Twiners – The stem body twines around the support without any
special organ of attachment. e.g., Cuscuta, Dolichos.
 SUBAERIAL STEM
Subaerial stems are the stems that do not rise up but grow just above
the ground.
• Runner: when stem grows and spread on the surface of soil eg.
Oxalis.
• Stolon: in it branches are small and stem condensed and grow in all
direction eg. Peppermint tree.
• Sucker: in it the main stem grow in the soil horizontally and
branches develop obliquely from nodes above the soil, eg.
Pineapple.
• Offset: a lateral branch with short internode and each node bearing
 STRUCTURE OF A STEM
• Underground stems are modified plant parts that derive
from stem tissue but exist under the soil surface.
• Many plants have underground modified stems that may be
mistaken for roots. Examples of underground stems include
corms, such as taro; rhizomes, such as ginger; and tubers,
such as potatoes.
 FUNCTIONS OF STEM
• Spreading out branches bearing leaves, flowers and fruits.
• It conducts water, minerals and photosynthates.
• Some stems perform the function of storage of food, support,
Protection and of vegetative propagation.
 STEMS OF MEDICINAL
IMPORTANCE
• Chondrodendron tomentosum gives tuboqurarine, which is skeletal
muscle relaxant used in general anesthesia.
 LEAF
• The leaf is a lateral generally flattened
structure borne on the stem. It develops at
the node and bears a bud in its axil.
• Theirmain function is photosynthesis and
food making, axillary buds are found in its
axil.
• All
the leaves of a plant is known as
phyllome.
• Axillary bud later develops into a branch.
• Leavesoriginated from shoot apical
meristem and are arranged in acropetal
order.
PARTS OF A LEAF
PARTS OF A LEAF
 PARTS OF A LEAF
Leaf is divided into three main parts
• Leaf base (Hypopodium)
 Leaves are attached to stem by leaf base and may bear two lateral
small leaf like structures called stipules.
 Inmonocotyledons, the leaf base expands into a sheath covering
the stem partially or wholly.
 In
some leguminous plants the leafbase may become swollen,
which is called the pulvinus.
 PARTS OF A LEAF
• Petiole (Mesopodium)
 Thepart of leaf connecting the lamina with the branch of
stem.
 Petiole help to hold the blade to light.
 Long thin flexible petioles allow leaf blades to flutter in wind,
thereby cooling the leaf and bringing fresh air to leaf surface
 PARTS OF A LEAF
• Lamina (Epipodium)
• It is a broad and flattened part of leaf.
• Its main functions are photosynthesis and transpiration.
• There is, usually, a middle prominent vein, which is known as the
midrib.
• Veinsprovide rigidity to the leaf blade and act as channels of
transport for water, minerals and food materials.
• The shape, margin, apex, surface and extent of incision of lamina
varies in different leaves.
 LAMINA (EPIPODIUM)
• Acicular – Lamina is long and pointed, like a needle. eg.
Pinus
• Lanceolate– In this type lamina is pointed or narrower at
the ends while broader in the middle. eg. Bamboo, Nerium
• Linear
– The lamina is long and narrow having parallel
margins. eg. Grass
• Ovate– In this type lamina is egg-shaped having broad
base with slight narrow top. eg. Ocimum, Banyan, China
rose.
• Cordate – Its shape is like a heart. eg. Betel.
 LAMINA (EPIPODIUM)
• Oblong – Long and broad lamina. eg. Banana
• Sagittate – The lamina is triangular in shape. eg. Sagittaria
• Spathulate – The lamina is broad spoon shaped. eg. Calendula
• Orbicular or Rotund – In this type the lamina is spherical. eg.
Lotus.
• Elliptical
or Oval – In this type the middle part of lamina is broad
while the ends are narrow and oval. eg. Guava.
• Oblique– In this types midrib divides, lamina into two unequal
halves. eg. Bignonia, Neem.
 VENATION OF LAMINA
• Thearrangement of veins and veinlets in leaves (Lamina) is
known as venation. It is of 2 types
• Reticulate:
It is found in dicots. Exception – Calophyllum,
Eryngium. It has parallel venation.
• Parallel:
It is found in monocots. Exception – Smilax, Dioscorea,
Alocasia, Colocasia. It has reticulate venation.
 RETICULATE VEIN
• Unicostate or pinnate – In this type of venation leaf have only one
principal vein or midrib that give off many lateral veins which
proceed toward margin and apex of lamina of the leaf and form a
network. eg. Mango, guava, Peepal.
• Multicostateor palmate – In this type of venation many principal
veins arising from the tip of petiole and proceed towards tip of
lamina.
 Multicostate divergent – Many principal veins arising from the tip
of petiole, diverge from the another toward the margin of leaf blade
eg. Cotton, Caster, Cucurbita, grape.
 RETICULATE VEIN
 Multicostate convergent – Many principal veins arising from
the tip of petiole. At the base of leaf they are closely
arranged but diverage from one another in middle part and
converge towards the apex of leaf. eg. Camphor, Zizyphus,
Tejpat, Chinarose, plum.
 PARALLEL VENATION
• In this type of venation, all veins run parallel to each other and they
do not from network.
• Unicostate or pinnate – This type of pattern having only one principal
vein, that gives off many lateral veins, which proceed toward the
margin of leaf blade in a parallel manner but they donot have veinlets.
eg. Banana, Ginger, Canna.
• Multicostate or palmate – Having many principal veins arising from
the tip of the petiole and proceeding upwards (towards the margin).
 Multicostate divergent – They do not divide into veinlets and do not
form network. eg. Coconut, Date palm
 Multicostate convergent – Many principal veins arising from
the tip of petiole run in a curved manner in lamina and
converge towards the apex of leaf blades. eg. – Wheat,
Sugar-cane, Bamboo.
• Furcate venation – The veins branch dichotomously but the
reticulum is not formed by the finer branches. eg. Adiantum
(fern).
 TYPES OF LEAF
• Simple Leaf – A leaf which may be incised to any depth, but not
down to the midrib or petiole, then this type of leaf called simple leaf.
eg. Mango, Chinarose, Ficus, etc.
• Compound leaf – A leaf in which the leaf blade is incised up to the
midrib or petiole, thus dividing it into several small parts, known as
leaflets. This type of leaf is known as compound leaf.

A bud is present in the axil of

petiole in both simple and
compound leaves, but not in the axil
of leaflets of the compound leaf.
 COMPOUND LEAF
• Pinnatelycompound leaf – In this type of leaf mid rib is known as
rachis. Leaflets are arranged on both sides of rachis. eg. Neem.
 Unipinnate – In this type of leaf, division occurs only once and
leaflets are directly attached on both sides of rachis.
 If
the number of leaflet is even, then leaf is known as paripinnate.
eg. Cassia fistula, Sesbania
 If
the number of leaflet is odd, it is known as imparipinnate. eg.
Rose, Neem
 Bipinnate – A twice pinnate compound leaf eg. Acacia, Gulmohar,
Mimosa.
 Tripinnate – A thrice pinnate compound leaf eg. Moringa.
 COMPOUND LEAF
• Decompound – A compound leaf, which is more than thrice
pinnate. eg. Carrot, Coriander.
 COMPOUND LEAF
• Palmate compound leaf – In this type incision of leaf are directed
from leaf margin to apex of petiole and all leaflets are attached on
the upper end of petiole.
 Unifoliate – When single leaflet is found. eg. Lemon
 Bifoliate – eg. Bauhinia, Regnelidium, Bignonia.
 Trifoliate – eg. Oxalis, Aegle, Trifolium
 Tetrafoliate – eg. Marsilea.
 Multifoliate – eg. Silkcotton.
 LEAVES OF MEDICINAL
IMPORTANCE
• Leaves:
• Theleaves of Digitalis Purpurea are the source of Digitoxin
and Digoxin, which are cardiac glycosides.
• Leavesof Eucalyptus give oil of Eucalyptus, which is
important component of cough syrup.
• Tobacco leaves give nicotine.
• Atropa belladonna gives atropine.
 PHYLLOTAXY
• Phyllotaxy
is the pattern of arrangement of leaves on the stem or
branch. This is usually of three types – alternate, opposite and
whorled.
• Inalternate type of phyllotaxy, a single leaf arises at each node
in alternate manner, as in china rose (figure a), mustard and sun
flower plants.
• Inopposite type, a pair of leaves arise at each node and lie
opposite to each other as in Calotropis and guava plants (figure
b).
• If
more than two leaves arise at a node and form a whorl, it is
called whorled, as in Alstonia (figure c).
 FLOWER
•A flower is a modified shoot wherein the shoot apical
meristem changes to floral meristem. Internodes do not
elongate and the axis gets condensed.
• The apex produces different kinds of floral appendages
laterally at successive nodes instead of leaves.
• When a shoot tip transforms into a flower, it is always
solitary (does not grow in groups or colonies).
 INFLORESCENCE
• The arrangement of flowers on the floral axis is termed as
inflorescence.
• Racemose – In this type of inflorescence the main axis continues to
grow and does not terminate in a flower and give off flower laterally
in acropetal manner where old flowers are arranged toward base
and young flowers are at tip. When peduncle is broad then flowers
are centripetally arranged.
 INFLORESCENCE
• In cymose type of inflorescence, the peduncle terminate in
a flower. In it the older flowers are present at tip and young
buds are arranged towards base. .The flowers are borne in
a basipetal order.
 PARTS OF A FLOWER
• The flower is the reproductive unit in the angiosperms.
•A typical flower has four different kinds of whorls arranged
successively on the swollen end of the stalk or pedicel, called
thalamus or receptacle.
• These are calyx, corolla, androecium and gynoecium.
• Calyx
and corolla are accessory organs, while androecium and
gynoecium are reproductive organs.
 PARTS OF A FLOWER
• The calyx is the outermost whorl of the flower and the
members are called sepals. Generally, sepals are green,
leaf-like and protect the flower in the bud stage. The calyx
may be gamosepalous (sepals united) or polysepalous
(sepals free).
 PARTS OF A FLOWER
• Corolla
is composed of petals. Petals are usually brightly
coloured to attract insects for pollination.
• Likecalyx, corolla may also be gamopetalous (petals united)
or polypetalous (petals free).
• Theshape and colour of corolla vary greatly in plants.
Corolla may be tubular, bellshaped, funnel-shaped or
wheel-shaped.
 PARTS OF A FLOWER
• Aestivation:The mode of arrangement of sepals or petals in
floral bud with respect to the other members of the same
whorl is known as aestivation. The main types of aestivation
are valvate (a), twisted (b), imbricate (c) and vexillary (d).
 PARTS OF A FLOWER
• Androecium is composed of stamens. Each stamen which
represents the male reproductive organ consists of a stalk
or a filament and an anther. Each anther is usually bilobed
and each lobe has two chambers, the pollen-sacs. The
pollen grains are produced in pollen-sacs. A sterile stamen
is called staminode.
• When stamens are attached to the petals, they are
epipetalous as in brinjal, or epiphyllous when attached to
the perianth as in the flowers of lily.
• The stamens in a flower may either remain free
(polyandrous) or may be united in varying degrees
(monoadelphous, diadelphous, polyadelphous).
 PARTS OF A FLOWER
• Gynoecium is the female reproductive part of the flower and is
made up of one or more carpels. A carpel consists of three parts
namely stigma, style and ovary.
• Ovary is the enlarged basal part, on which lies the elongated tube,
the style.
• The style connects the ovary to the stigma.
• The stigma is usually at the tip of the style and is the receptive
surface for pollen grains.
• After fertilisation, the ovules develop into seeds and the ovary
matures into a fruit.
• In some flowers like lily, the calyx and corolla are not
distinct and are termed as perianth.
• When a flower has both androecium and gynoecium, it is
bisexual.
•A flower having either only stamens or only carpels is
unisexual.
• When a flower can be divided into two equal radial halves in
any radial plane passing through the centre, it is said to be
actinomorphic, e.g., mustard, datura, chilli.
• When it can be divided into two similar halves only in one
particular vertical plane, it is zygomorphic, e.g., pea,
gulmohur, bean, Cassia.
•Aflower is asymmetric (irregular) if it cannot be divided into
two similar halves by any vertical plane passing through the
centre, as in canna.
•Aflower may be trimerous, tetramerous or pentamerous
when the floral appendages are in multiple of 3, 4 or 5,
respectively.