The document describes the key parts and structures of leaves. It defines leaves and their main functions as photosynthesis, gaseous exchange, and transpiration. The summary describes: - Leaves have distinct structures including the lamina, petiole, stipules, base, apex, margins, and venation. - Leaves can be simple or compound. Compound leaves are further divided into pinnate and palmate types. - Leaves exhibit a variety of shapes, margins, bases, apices, surfaces, and phyllotaxy. Their venation can be parallel or reticulate. - Leaves undergo various modifications to enhance functions like support, protection, and storage.

1. PHARMACOGNOSY AND PHYTOCHEMISTRY-II
BATCH-B
Only B Batch 1

2. Define &
Characteristics
■ Leaves are flat, thin green, appendages to
the stem, containing supporting and
conducting strands in their structure. They
develop in such a way that older leaves are
placed at the base while the younger ones at
the apex.
 Leaf is a thin, expanded, green structure.
 The green colour of the leaf is due to the
presence of chlorophyll pigment.
 It is exogenous in origin.
 It is bome on the stem at the node.
 An auxiliary bud is often present in the axil of
each leaf.
 It has limited growth.
 It does not possess apical bud or a regular
growing point.
Only B Batch 2

3. [A] A typical angiospermic leaf
Only B Batch 3
Parts and Description Diagram
LEAF BASE OR HYPOPODIUM:
 The part of leaf attached to the stem or branch is known as leaf base.
It may assume different shape in different plants.
For example:- Pulvinus, Sheath, Stipules

4. [A] A typical angiospermic leaf
Only B Batch 4
PETIOLE:
 It is the stalk of leaf with which leaf blade is attached to the stem. It is
also known as mesopodium. It may be present in leaf or may be absent in
leaf.
 Leaves with petiole are called petiolate, and those without petiole sessile
 In few other cases, the petiole enlarges to such an extent to form the leaf
like structure as in Australian acacia and is known asphyllode.
 For example:- clematis.

5. [A] A typical angiospermic leaf
Only B Batch 5
LAMINA OR LEAF BLADE:-
 The flat expanded part of the leaf is lamina or leaf blade (Epipodium).
 Lamina may be thick as in xerophytic leaves.
 Lamina may be thin as in hydrophytes or intermediate as in mesophytes
 For Example:- Dicotyledonous leaves.
STIPULES:-
 A stipule is considered a "bud scale" if it is hard or scaly and protects
leaf buds as they form.
 A stipule is considered "tendrillar" if they are long thin tendrils, and are
generally used by climbing plants.
 For example:- Coffee plant

6. [A] A typical angiospermic leaf
Stipules
Function
Foliaceous Tendrillar Bud Spiny
Location
Free lateral Axillary Adnate
Ochreate
stipule
Inter-
petiolar
Only B Batch 6

7. FUNCTION TERMS
Tendrillar stipules:
The stipules get modified into coiled, tendrils helping the plant to
climb, i.e. Indian sarsaparilla (Smilax microphylla)
Foliaceous stipules:
In case of plants with compound leaves some of the leaflets get
converted into tendril and the stipules expand to form the flat surface
and carry on photosynthesis, i.e. Lathyrus or pisum
Bud stipules:
The development and unfolding of the leaf the bud stipule falls off
Spiny stipules:
The stipules get converted into spines and help against browsing
animals as in the case of Acacia and Zizyphus.
Only B Batch 7
[A] A typical angiospermic leaf

8. [A] A typical angiospermic leaf
LOCATION TERMS
Free lateral:
These are free and located on either side of the leaf as in China rose
Adnate:
When the stipules unite with the petioles forming wing like structure
are known as adnate stipules, i.e. Groundnut, rose, etc.
Inter-petiolar:
When stipules are located in between thetwo petioles of two leaves as
in ixora.
Axillary:
When two stipules unite becoming axillary to the leaves.
Ochreate stipules:
These form a hollow tube around the stem as in Polygonum.
Only B Batch 8

9. [B] Shape of the lamina of leaves
Only B Batch 9
 Various shapes of the leaves are due to various types or shapes of lamina. It may be one of the following:
TERMS
Acicular:
Needle like
e.g. pinus.
Subulate:
With acute apex and recurved point,
e.g. Ephedra sinica.
Linear:
When it is long, narrow and flat.
e.g. Grasses
Oblong:
Broad leaves with two parallel margins and abruptly tapering apex,
e.g. Banana
Lanceolate:
Which look like lance or spear shaped,
e.g. nerium, senna.

10. [B] Shape of the lamina of leaves
Only B Batch 10
DESCRIPTION
Obovate:
Broad apex and narrow base, e.g. Jangalibadam.
Obcordate:
Inversely heart shaped, i.e. base is narrow but apex is broad, e.g.
Oxalis.
Spathulate:
Like spatula or spoon shaped as in calendula and drosera
Cuneate:
Wedge shaped e.g. pista.
Cordate:
Heart shaped, e.g. betel

11. [B] Shape of the lamina of leaves
Only B Batch 11
DESCRIPTION
Runcinate
With the lobes convex before and straight behind, pointing backward like
the teeth of the double saw, e.g. dendelion leaf.
Rotund (Orbicular)
When the blade is circular or round, e.g. lotus
Elliptical or oval
When the leaves are narrow at the base and apex but broad in the
middle e.g. guava, vinca, etc.
Peltate
When the lamina is shield shaped and fixed to the stalk by the centre.
Sagittate
Arrow shaped e.g. arum.
Hastate
When the two lobes of sagittate leaf are directed outwards e.g. ipomoea.

12. [B] Shape of the lamina of leaves
Only B Batch 12
DESCRIPTION
Ovate
Egg shaped or broad base and narrow apex,
e.g. China rose, Buchu.
Lyrate
When it is lyre shaped or the blade is divided into lobes
with large marginal lobe, e.g. radish mustard.
Reniform
Kidney shaped, e.g. Indian pennywort.
Auriculate
When the leaf has got ear like projections at the base

13. [C] Leaf margins
Only B Batch 13
Leaf margin may be of the following types:
DESCRIPTION TERMS
When it is even and smooths, i.e. senna, eucalyptus. Entire
With slight undulations like Ashok. Sinuate or wavy
When the teeth are round as in digitalis Crenate
Toothed margin, teeth directing outwards such as margosa, melon Dentate
When it is like the teeth of the saw such as rose, China rose, etc Serrate
It is fringed with hairs. Ciliated
Lobed serrate margin Biserrate

14. [C] Leaf margins
Only B Batch 14

15. [D] Leaf apices
Only B Batch 15
The apex of the leaf may be one of the following kinds:
DESCRIPTION TERMS
Rounded tip, i.e. banyan Obtuse
When it is pointed to form acute angle, but not stiff, i.e. hibiscus Acute
Pointed tip with much elongation, peepal. Acuminate
When the apex is curved backward Recurved
With spiny tip like date palm. Cuspidate
Rounded apex ending abruptly in a short point i.e vinca, ixora. Mucronate
Broad tip with slight notch, i.e. pistia. Retuse
When tip is deeply notched as in bambinia. Emarginate
Tip forming a tendril such as Gloriosa-superba. Tendrillar

16. [D] Leaf apices
Only B Batch 16

17. [E] Leaf bases
Only B Batch 17
The lower extremity of the lamina of the leaf may exhibit one of the following shapes
DESCRIPTION TERMS
Equal as in vasaka.. Symmetrical
Unequal as in senna or datura. Asymmetrical
As in digitalis. Decurrent
As in betel Cordate

18. [F] Leaf surface
Only B Batch 18
It may be of the following types:
DESCRIPTION TERMS
When surface is smooth and free of hair or any outgrowth, e.g vasaka, datura Glabrous
When harsh to touch, digitalis.. Rough
When covered with hairs Hairy
When covered with sticky substance, tobacco. Glutinous
When covered with waxy coating, castor. Glaucous
Covered with straight, short hair, e.g. senna. Pubescent

19. [G] Types of leaves
Only B Batch 19
Leaves
Simple
leaves
Compound
leaves
Pinnate
Unipinnate Tripinnate Decomposed
Palmate
Unifoliate Trifoliate Multifoliate

20. [G] Types of leaves
■ SIMPLE LEAVES:-
1) A leaf which has only one leaf blade or
lamina is called a simple leaf.
2) It may be stipulate or exstipulate, petiolate
or sessile, but always possess axillary bud
in its axil.
3) It may have an undivided lamina or may be
lobed.
4) e.g. vasaka, digitalis, eucalyptus, datura,
carica, castor and argemone.
■ COMPOUNDS LEAVES:-
1) A compound leaf consists of more than
one leaf blade or the lamina.
2) The compound leaf is divided into several
segments called leaflets or pinnae.
3) e.g. senna, tamarind, acacia
Only B Batch 20
Taking into consideration the nature of the lamina of the leaves, they are classified into
two mains groups:

21. [G] Types of leaves
Only B Batch 21
There are Two kind of leaves:-

22. [G] Types of leaves
(a) Pinnate Compound
Leaves
1. These are sub-classified as under
depending upon the number of
rachis.
2. (an axis bearing the leaflets in
pinnate compound leaf is known as
rachis)
3. They are further divided as:
(b) Palmate Compound
Leaves
1. In this type the leaflets are born by
the petiole of the leaf.
2. Depending upon the number of
leaflets in a compound palmate
leaf.
3. They are further divided as:
Only B Batch 22
Compound leaves have been further classified as (a) pinnate compound leaves and (b) palmate
compound leaves.

23. [G] Types of leaves
Only B Batch 23
(a)Pinnate Compound Leaves
Unipinnate compound leaves: Where in only one rachis
bearing the leaflets is present.
o When an even number of leaflet is present, it is known as
paripinnate, e.g. tamarind, gulmohor e.t.c
Bipinnate compound leaves: It consists of primary rachis and
secondary rachis.
oThe secondary rachis only bears the leaflets, e.g. acacia
Tripinnate compound leaves: These contain primary,
secondary and even tertiary rachis. Tertiary rachii only bear
the leaflets as in moringa, oroxylon
Decompound leaf: Wherein compound leaf is much
divided irregularly as in coriander, carrot, anise, etc.

24. [G] Types of leaves
Only B Batch 24
(b) Palmate Compound Leaves
Unifoliate compound leaf: Lemon.
Trifoliate compound leaf: Bael, wood apple.
Multifoliate compound leaf: Bombax, alstonia

25. [H] Venation
Only B Batch 25
 The arrangement of veins and veinlets in the lamina is known as venation.
 The veins are in facts conducting strands of lamina.
 They are concerned with the conduction of water, mineral salts and food and form the
structural framework of the lamina.
Parallel venation Reticulate venation:-

26. [H] Venation
Only B Batch 26
Venation
Reticulate
Unicostate-
reticulate
Multicostate-
reticulate
Parallel
Unicostate
parallel
Multicostate
parallel

27. [H] Venation
 Reticulate venation:-
1. When the veins and veinlets form a network, it is called reticulate venation.
2. The prominent vein in the centre of the leaf is known as midrib.
3. Here the midrib is centrally placed and veins and distributed laterally.
4. It is found in dicotyledonous plants.
5. In the flowering plants two types of venations exist:
a) Unicostate-reticulate – With a single mid-vein e.g.Mango
b) Multicostate-reticulate – With two or more prominent veins e.g. Zizyphus.
-- It may be convergent or divergent.
Only B Batch 27

28. [H] Venation
 Parallel venation:-
1. In this type of venation, veins in lamina run almost parallel to one another.
2. It is found commonly in monocotyledonous plants.
3. It is of the following two types:
A. Unicostate-Parallel:- The veinlets and veins arise parallel to one another on each
side as in banana and canna.
B. Multicostate-parallel:- many number of main veins of equal strength arise from the
tip or the petiole and run parallel to each other. E.g. grass, rice, bamboo, etc.
Only B Batch 28

29. [I] Phyllotaxy
■ Phallotaxy is the arrangement of leaves on the stem and branches.
Only B Batch 29

30. [I] Phyllotaxy
 Alternate phyllotaxy:-
1) In this type, single leaf arises at each node.
2) The leaves arise laterally on the stem or branches.
3) E.g. sunflower, mango, china rose, Mustard etc.
 Opposite Phyllotaxy:-
In this type, two leaves arise from each node in opposite direction. It is of Two types:
i. Decussate:- When one pair of leaf is placed at right angle to next or lower pair of
leaf., It is said to be opposite decussate phyllotaxy. E.g. Calotropis, Ocimum, etc.
ii. Superposed:- In this type, all the pairs of leaves on the stem are arranged one
above the other. E.g. jamun, Guava, etc.
Only B Batch 30

31. [I] Phyllotaxy
 Whorled:-
In this type more than two leaves arise from each node and form a whorl around it
e.g.Nerium, aistania.
 Leaf mosaic:- In this type, the leaves are so arranged that there will not be any over
shading and all the leaves are exposed properly. e.g. Oxalis and acalypha
Only B Batch 31

32. [J] Modifications of Leaves
Function of leaf
Primary
function
photosynthesis
gaseous
exchange
transpiration
Secondary
function
support protection
storage of food
material
Only B Batch 32
To perform these secondary functions the leaf undergoes structural and physiological
changes called modifications

33. [J] Modifications of Leaves
Only B Batch 33
Modifications
of Leaves
Leaf spines Leaf tendrils Phyllode
Pitcher and
bladder
Scale Leaves

34. [J] Modifications of Leaves
Leaf tendrils: Leaves get modified into slender, coiled and wiry
structures as seen in Lathyrus peas and gloriosa for support to the
plant
Leaf spines: For the sake of protection certain leaves get
converted into spines as seen in Aloe, argemone, acacia,etc
Phyllode: Petiole gets modified to flat leaf-like phyllode to reduce
the transpiration, e.g. Australian acacia.
Scale Leaves: In ginger and potato they protect the terminal buds,
while in onion and garlic they store food material.
Pitcher and bladder: These are specially developed modifications
of leaves to capture and digest insects in case of carnivorous
plants, e.g. Utricularis Bladder wort and Nepenthes.
Only B Batch 34

35. REFERENCE
 Biren Shah, Avinash Seth-Textbook of Pharmacognosy and Phytochemistry-Elsevier
India (2012) Page no. 47
 www.google.com
Only B Batch 35