68 CBSE New Pattern Biology XI ~ (Term-I)

05
Morphology of
Flowering Plants
Quick Revision
l Morphology deals with the study of external The Flower
features, forms and relative position of plant Flower is the reproductive unit in the angiosperms. It is
organs. meant for sexual reproduction. Morphologically, it is
l Plants adopt various morphological features considered as a shoot bearing nodes and modified floral
according to the surrounding environment. leaves.
The two main plant parts are the underground l A flower arises in the axil of a leaf-like structure
root system and the above ground shoot called bract. Flowers with bracts are called
system. bracteate and those without bracts are called
ebracteate.
Inflorescence l The terminal and swallen part of the axis of the
It is the arrangement of flowers on the floral axis of flower is the receptacle or thalamus. The
stem. receptacle contains sepals, petals, stamens and
The inflorescence can be of following three types carpels. If the leaves are present on the pedicel,
l Racemose inflorescence In this type of they are called bracteoles.
inflorescence, the main axis continues to grow l Flowers that do not have distinct calyx and corolla
and the flowers are borne laterally in an are called perianth.
acropetal or centripetal succession. l A flower is either unisexual (having either stamen
l Cymose inflorescence In this inflorescence, or pistil) or bisexual (having both stamen and
the tip of the main axis terminates in a flower pistil).
and further growth continues by one or more l On the basis of the number of floral appendages
lateral branches, which also behave like the present, a flower may be trimerous, tetramerous
main axis. The flowers are borne in a or pentamerous.
basipetal order. Hence, it is limited in growth. l Insertion of floral parts (forms of thalamus)
l Special inflorescence It mainly involves Based on the position of ovary with respect to
highly modified and densely crowded other floral whorls (calyx, corolla and androecium),
inflorescence. It can be divided into following the flowers are of following three types
types, i.e. cyathium, verticillaster n
Hypogynous flower Ovary is present at the top of
and hypanthodium (Ficus relegiosa). thalamus.
CBSE New Pattern Biology XI ~ (Term-I) 69

n
Perigynous flower Margin of thalamus grows n
Imbricate Both margins of one petal/sepal
upwards forming a cup-like structure. overlaps and another petal/sepals are
n
Epigynous flower Having fused thalamus and overlapped, rest other are twisted, e.g.
ovary. Cassia.
n
Vexillary/Papilionaceous Large petal
(standard) overlaps the two lateral petals
(wings), which in turn overlap the two
smallest anterior petals (keel), e.g. Pisum.

(a) (b) (c) (d)

Position of floral parts on thalamus : (a) Hypogynous,
(b) and (c) Perigynous, (d) Epigynous
l Symmetry of a flower The symmetry of a
flower depends upon the shape, size and
arrangement of the floral parts. On the basis of
this, it can be actinomorphic (radial symmetry,
e.g. Datura) or zygomorphic (bilateral symmetry, (a) (b) (c) (d)
e.g. Cassia).
Types of aestivation in corolla : (a) Valvate,
l Placentation is the arrangement of ovules inside (b) Twisted, (c) Imbricate, (d) Vexillary
an ovary. Placenta refers to the parenchymatous
cushion present inside the ovary where ovules are 3. Androecium (stamen) male reproductive part
borne. These may be marginal (e.g. peas), axile of flower. Each stamen consists of a filament
and an anther. The anther contains pollen sacs
(e.g. China rose), parietal (e.g. Cucurbita),
where pollen grains are formed.
free-central (e.g. Dianthus) and basal (e.g. Aster).
n
On the basis of cohesion and adhesion of their
Parts of a Flower parts, stamens may be monadelphous
l A typical flower consists of four distinct parts, i.e. (filaments united to form one bundle, e.g.
the calyx, corolla, androecium and gynoecium. Hibiscus), diadelphous (filaments united to
The calyx and corolla are accessory or form two bundles, e.g. Pisum), polyadelphous
non-essential parts and the androecium and (filaments united to form more than two
gynoecium are essential parts. bundles, e.g. Citrus), syngenesious (only
anthers are united in bundle, e.g. Helianthus),
l Different parts of flowers are as follows
synandrous (both anthers and filament united
1. Calyx is the outermost, green in colour, leaf-like to form bundle, e.g. Cucurbita).
whorl that protects the bud stage of flower. The n
When stamens are adhered to petals the
individual members are sepals. The calyx may conditions is known as epipetalous (e.g.
be gamosepalous (sepals united) or Solanum) and when stamens are attached to
polysepalous (sepals free). perianth the condition is called epiphyllous,
2. Corolla is the whorl of brightly coloured petals e.g. lily. If stamens or anthers are attached to
to attract insects for pollination. Petals are also gynoecium condition is known as
either fused (gamopetalous) or free gynandrous (e.g. Calotropis).
(polypetalous). 4. Gynoecium (pistils or carpels) female
l Aestivation It is the arrangement of sepals or reproductive part of flower consisting of the
petals in relation to one another in a floral bud. receptive and sticky stigma, the elongated
n
Valvate Units in a whorl just touch at stalk style and the enlarged base ovary that
margin, without overlapping, e.g. Calotropis. bears ovules. When more than one carpels are
n
Twisted One margin of unit overlaps that of present they may be apocarpous (free) as in
the next one, e.g. Hibiscus. Viscum or syncarpous (united) as in Hibiscus.
70 CBSE New Pattern Biology XI ~ (Term-I)

Semi-Technical Description of a Typical Flowering Plant

l Flower is the distinct identifying feature of a plant. To describe the characteristics of a flower in brief,
floral formula and floral diagram are used. They use some specific symbols as
Br – Bracteate P – Perianth (Unit-tepals)
Ebr – Ebracteate A – Androecium (Unit-stamens)
⊕ – Actinomorphic or regular flower G – Gynoecium (Unit-carpels)
% – Zygomorphic or irregular flower G – Superior ovary
%
& – Bisexual flower G – Inferior ovary
– Female flower 1, 2, 3, 4, … ∞ – Number of units
&
% – Male flower () – Fused
K – Calyx (Unit-sepals)
C – Corolla (Unit-petals) CA – Epipetalous condition

Description of Some Important Families

Characteristics Solanaceae Liliaceae

General Commonly known as potato family. It Commonly called as lily family. It is a
description is distributed in tropics and subtropics. representative of monocots.
Plant structure Herb, shrub and small trees. Perennial herb.
Stem structure Herbaceous, rarely woody, hairy, hollow, Stem may be underground partially.
underground (potato).
Inflorescence Solitary, axillary or cymose. Solitary/cymose often umbellate clusters.
Flower Bisexual and actinomorphic, rarely Bisexual and actinomorphic.
zygomorphic.
Calyx Sepal five united, persistent, valvate. Perianth [6 tepals arranged in two whorls
( 3 + 3). Free or rarely united, valvate].
Corolla Five united, valvate. —
Androecium Stamens five, epipetalous. Stamens 6 (3 + 3), epipetalous
Gynoecium Bicarpellary, syncarpous and superior. Tricarpellary, syncarpous and superior.
Fruit Berry or Capsule. Capsule and rarely berry.
Seed Many and endospermic. Endospermic.
Floral formula ⊕ %K ( 5)C( 5) A ( 5) G ( 2) Br⊕ % P( 3 + 3) A 3 + 3G ( 3)
+ +
Economic Plants of this family are source of food Plants of this family are used as ornament
importance (potato underground stem), tomato and and medicines Aloe, vegetable (Asparagus)
brinjal, spices (chilli), medicines and colchicine (Colchicum autumnale).
(Belladonna), fumigatory (tobacco).
Floral diagram
CBSE New Pattern Biology XI ~ (Term-I) 71

Objective Questions
Multiple Choice Questions 6. Identify the given diagram and choose
1. A flower is a modified shoot because the incorrect option.
(a) certain flowers have well-developed nodes
and internodes
(b) it arises in the axile of plants
(c) the growing point of thalamus may give rise
to shoots
(d) All of the above
(a) The main axis terminates into a flower
2. When a shoot tip transforms into a (b) Flowers are basipetally arranged
flower, it is always (c) Growth of the peduncle is determined
(a) solitary (d) Older flowers are towards the base and
(b) axillary younger at the apex
(c) racemose 7. In an inflorescence, where flowers are
(d) cymose borne laterally in an acropetal
3. Inflorescence is the arrangement of succession, the position of the youngest
(a) leaves on the floral axis floral bud shall be (NCERT Exemplar)
(b) buds on the floral axis (a) proximal (b) distal
(c) flowers on the floral axis (c) intercalary (d) any where
(d) petioles on the floral axis 8. A typical flower has four different kinds
4. Depending on whether the apex gets of whorls arranged on end of the stalk
converted into a flower or continues to or pedicel called
grow, how many major types of (a) peduncle (b) thalamus
inflorescences are defined? (c) receptacle (d) Both (b) and (c)
(a) Two (b) Three 9. Perianth is the condition in which
(c) Four (d) Five (a) calyx and corolla are not distinct
5. In racemose inflorescence, (b) calyx is present, but corolla is absent
(c) corolla is present, but calyx is absent
I. the main axis continues to grow into a
flower. (d) calyx and corolla are not present
II. flowers are borne in acropetal manner. 10. I. When flower has both an androecium
III. young flowers are present towards the and gynoecium, it is called ... A.... .
base and older at the apex. II. When flower has either stamens or
only carpel, it is called ... B.... .
Choose the correct option to complete
the statement. Fill up the blanks by choosing
(a) Only I
appropriate options for A and B.
(b) II and III (a) A–bisexual, B–unisexual
(b) A–unisexual, B–bisexual
(c) Only III
(c) A–bisexual, B–hermaphrodite
(d) I and II
(d) A–hermaphrodite, B–bisexual
72 CBSE New Pattern Biology XI ~ (Term-I)

11. Choose the incorrect match. (a) the margin of thalamus grows upwards
enclosing
(a) Actinomorphic flower — Mustard
(b) ovary is said to be inferior
(b) Zygomorphic flower — Gulmohar
(c) the flower is said to be perigynous
(c) Asymmetrical flower — Bean
(d) it is seen in the flowers of guava and
(d) All of the above cucumber
12. Which of the following statement is 16. Match the following columns.
correct?
(a) Actinomorphic are bilaterally symmetrical Column I Column II
flowers (Parts of flower) (Description)
(b) Zygomorphic are radially symmetrical A. Calyx 1. Female
flowers reproductive part
(c) Asymmetric are irregularly symmetrical B. Corolla 2. Male
flowers reproductive part
(d) All of the above
C. Androecium 3. Outermost whorl
13. Which of the following represents of flower
hypogynous condition? D. Gynoecium 4. Composed of
petals
Codes
A B C D
(a) 4 1 3 2
(b) 3 2 1 4
(a) (b)
(c) 3 4 2 1
(d) 2 1 3 4
17. Read the following statements and
choose the option with correct
statements.
I. Generally sepals are green, leaf like
(c) (d) and protect the flower in the bud stage.
II. Petals are usually bright coloured to
14. Select the correct match with respect to attract insect pollinators.
the position of floral parts on thalamus.
III. The shape and colour of corolla vary
(a) Hypogynous — Half inferior — Guava
greatly in plants.
(b) Epigynous — Superior — Cucumber
(c) Perigynous — Inferior — Ray florets of IV. Corolla may be tubular, bell-shaped,
sunflower funnel-shaped or wheel-shaped.
(d) Hypogynous — Superior — China rose (a) I and II (b) III and IV
15. All statements are correct with respect (c) I, III and IV (d) I, II, III and IV
to the figure given below, except. 18. Match the following columns.
Column I Column II
A. Sepals free 1. Gamopetalous
B. Petals united 2. Gamosepalous
C. Petals free 3. Polysepalous
D. Sepals united 4. Polypetalous
CBSE New Pattern Biology XI ~ (Term-I) 73

Codes 23. Find out the pairs, which are correctly

A B C D
matched with respect to aestivation of
(a) 3 1 2 4
(b) 3 4 1 2
petals.
(c) 2 1 4 3 I. Valvate – Calotropis
(d) 3 1 4 2 II. Twisted – Bean
19. The mode of arrangement of sepals or III. Imbricate – Cassia
petals in a floral bud with respect to the IV. Vexillary – China rose
other members of same whorl is known (a) II and IV (b) I and II
as (c) I and III (d) III and IV
(a) aestivation (b) cohesion
(c) placentation (d) adhesion 24. Staminode is a fertile stamen.
(a) True
20. Which type of aestivation occurs when (b) False
sepals or petals in a whorl just touch
(c) Cannot say
one another at the margin without
(d) Partially true or false
overlapping?
(a) Imbricate aestivation 25. The technical term used for the
(b) Valvate aestivation androecium in a flower of China rose
(c) Twisted aestivation (Hibiscus rosa-sinensis) is
(d) Vexillary aestivation (a) monadelphous (b) diadelphous
(c) polyandrous (d) polyadelphous
21. Arrange in correct order according to
the given figures. 26. Match the following columns.
Column I Column II
A. When stamens 1. Epipetalous
unite into more
A B C D than two bundles
(a) A – Imbricate, B – Vexillary, C – Valvate, B. When stamens 2. Epiphyllous
D – Twisted are attached to
(b) A – Vexillary, B – Valvate, C – Twisted, the petals
D – Imbricate
C. When stamens 3. Diadelphous
(c) A – Valvate, B – Twisted, C – Vexillary are attached with
D – Imbricate perianth
(d) A – Valvate, B – Twisted, C – Imbricate,
4. Polyadelphous
D – Vexillary
Codes
22. Aestivation of petals in the flower of A B C A B C
cotton is correctly shown in (a) 3 1 2 (b) 4 1 2
(c) 3 2 1 (d) 4 2 1
(a) (b) 27. Select the incorrect pair out of the
following.
(a) Epipetalous – Brinjal
(b) Diadelphous – Cucurbita
(c) (d) (c) Polyadelphous – Citrus
(d) Epiphyllous – Lily
74 CBSE New Pattern Biology XI ~ (Term-I)

28. In a carpel, …A… is the enlarged basal 34. Match the following columns.
part, on which lies the elongated tube,
…B… . The …C… is the tip of carpel, Column I Column II
(Placentations) (Examples)
which is receptive for pollen grains.
(a) A–stigma, B–style, C–ovary A. Basal 1. Mustard
(b) A–ovary, B–style, C–stigma B. Axile 2. China rose
(c) A–style, B–stigma, C–ovary C. Parietal 3. Dianthus
(d) A–stigma, B–ovary, C–style
D. Free-central 4. Sunflower
29. The expression ‘gynoecium is Codes
apocarpous’ implies that the
A B C D
(a) gynoecium comprises only one pistil which (a) 2 3 4 1
is fused with the stamen (b) 1 2 3 4
(b) gynoecium comprises more than one (c) 4 2 1 3
carpel, all of which are free (d) 3 4 1 2
(c) gynoecium comprises only one carpel
which is free 35. In a multicarpellary syncarpous
(d) gynoecium comprises more than one carpel unilocular ovary, if the ovules are borne
which are fused on the central axis and septa are absent
30. Gynoecium with fused carpels is called this is defined as
(a) marginal placentation
(a) syncarpous (b) apocarpous
(b) parietal placentation
(c) syngenesious (d) None of these
(c) axile placentation
31. Placentation can be defined as an (d) free-central placentation
arrangement of
(a) ovules within the ovary
36. In the diagram of types of placentation
given below, A, B, C and D,
(b) synergids within the ovary
respectively represent
(c) carpels in a flower
(d) pistils in a flower
32. In marginal placentation, the ovules are
arranged
(a) along the inner wall of carpel in a
syncarpous ovary A B
(b) along the margin of single carpel
(c) in the middle of the ovary
(d) to the base of the ovary
33. Axile placentation is found in
syncarpous ovaries. In this placentation,
C D
the ovules are arranged along the
(a) base of the ovary (a) A–Basal, B–Axile, C–Parietal, D–Free-central
(b) margin of the ovary (b) A–Free-central, B–Parietal, C–Basal, D–Axile
(c) axis in the centre of the ovary (c) A–Axile, B–Basal, C–Parietal, D–Free-central
(d) None of the above (d) A–Parietal, B–Axile, C–Free-central, D–Basal
CBSE New Pattern Biology XI ~ (Term-I) 75

37. When both essential floral organs 42. Brinjal, datura and tobacco belong to
(stamens and carpels) are present in a family
flower, we write …… in its floral (a) Liliaceae (b) Fabaceae
formula. (c) Solanaceae (d) Leguminosae
%
(a) & (b) %
43. The correct floral formula of chilli is
(c) & (d) ⊕
(a) r&
% K2 +2 C4 A2 + 4 G(2)
38. & stands for ...A... . (b) Br %K4C4A1G1
⊕ stands for ...B... . % K(5) C(5) A5 G(2)
(c) r &
% stands for ...C... . (d) r &
% P3 + 3 A3 + 3 G(3)
Here, A to C refer to 44. I. Plants belonging to the family…A…
(a) A–Female, B–Actinomorphic, possesses a persistent calyx.
C–Zygomorphic II. The family …B… mainly contains
(b) A–Male, B–Actinomorphic, C–Zygomorphic monocotyledonous plants.
(c) A–Male, B–Zygomorphic,
C–Actinomorphic Choose the correct option to fill in the
(d) A–Female, B–Zygomorphic, blanks ‘A’ and‘B’.
C–Actinomorphic A B
(a) Fabaceae Poaceae
39. What would we interpret if % is given
for a flower in its floral formula? (b) Solanaceae Fabaceae
(c) Solanaceae Liliaceae
(a) Any vertical section passing through its
(d) Asteraceae Solanaceae
centre divides it into two equal vertical
halves 45. Bicarpellary obligated placed
(b) Only one vertical section divides it into syncarpous ovary with axile
equal vertical halves placentation is found in
(c) Cannot be divided into equal vertical halves
(a) potato family (b) lily family
by any vertical section
(c) pea family (d) mustard family
(d) Only one vertical section passing through
its centre divides it into two equal vertical 46. Given are two floral diagrams A and B.
halves
40. Give the symbol of bicarpellary
syncarpous, inferior ovary
(a) G (2 ) (b) G0
(c) G2 (d) G (2 )
41. Which of the following statements is
correct with reference to the flowers of A B
family–Solanaceae? The correct floral diagram of the family
(a) Pentamerous, actinomorphic, unisexual, to which tulip and tomato belongs are
hypogynous …… and ……, respectively.
(b) Pentamerous, zygomorphic, bisexual, (a) A, B (b) B, B (c) B, A (d) A, A
epigynous
(c) Pentamerous, bisexual, actinomorphic, 47. Tricarpellary, syncarpous gynoecium is
hypogynous found in flowers of Solanaceae.
(d) Trimerous, actinomorphic, bisexual, (a) True (b) False
hypogynous (c) Cannot say (d) Partially true or false