Biology Today

80 Pages·2016·9.46 MB·English

by  Anil Ahlawat

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Vol. XVIII No. 5 May 2016
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CONTENTS
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8 PMT Essential (XI)
Morphology of Flowering Plants-II
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Practice Questions 2016
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MTBIOLOGY TODAY | MAY ‘16 7
The content for PMT Biology is
very vast and does not allow
students to engage in inquiry
and develop meaningful
knowledge. An essential topic
for PMT is presented here to
enable students grasp the
topic, analyse the type of
questions appearing in PMTs,
and SCORE HIGH.
MORPHOLOGY OF FLOWERING PLANTS-II
INFLORESCENCE
The arrangement and mode of distribution of flowers on the shoot system of a plant
is called inflorescence. The common axis bearing the flowers is called peduncle.
Stalk of the individual flower is called pedicel. Flowers develop on the peduncle in
the axis of bracts. The different types of inflorescence are :
Solitary
Flowers occur singly or are separated from other flowers of the same plant by
means of vegetative regions. It is of following types:
(i) Solitary terminal : Single flower on terminal part of the branch (cid:72)(cid:17)(cid:74)(cid:17), Poppy
(ii) Solitary axillary : Single flower in the axil of leaf,(cid:3)(cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:43)(cid:76)(cid:69)(cid:76)(cid:86)(cid:70)(cid:88)(cid:86)
Racemose
An indeterminate type of inflorescence with indefinite growth.(cid:3)The arrangement
of flowers on peduncle is either acropetal ((cid:76)(cid:17)(cid:72)(cid:17)(cid:15)(cid:3)younger towards the apex and
older towards the base) or centripetal (cid:11)(cid:76)(cid:17)(cid:72)(cid:17)(cid:15)(cid:3)younger towards the centre and Fig.: Solitary inflorescence of (cid:43)(cid:76)(cid:69)(cid:76)(cid:86)(cid:70)(cid:88)(cid:86)
older towards the periphery).
8 MTBIOLOGY TODAY | MAY ‘16

Simple Racemose
(Peduncle is unbranched)
Typical raceme Spike
Pedicellate bisexual flowers arranged in Sessile flowers arranged in acropetal succession
acropetal succession (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:37)(cid:85)(cid:68)(cid:86)(cid:86)(cid:76)(cid:70)(cid:68). (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:38)(cid:68)(cid:79)(cid:79)(cid:76)(cid:86)(cid:87)(cid:72)(cid:80)(cid:82)(cid:81)(cid:15)(cid:3)(cid:36)(cid:70)(cid:75)(cid:92)(cid:85)(cid:68)(cid:81)(cid:87)(cid:75)(cid:72)(cid:86)(cid:17)
Umbel
All the pedicellate flowers arise from a single
Corymb
point in a centripetal fashion. The peduncle
Older flowers have longer pedicel and
is very much reduced,(cid:3)(cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:43)(cid:92)(cid:71)(cid:85)(cid:82)(cid:70)(cid:82)(cid:87)(cid:92)(cid:79)(cid:72)(cid:15)(cid:3)
younger flowers have shorter pedicel. As a
(cid:51)(cid:85)(cid:88)(cid:81)(cid:88)(cid:86).
result all the flowers are brought to the same
level (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:44)(cid:69)(cid:72)(cid:85)(cid:76)(cid:86)(cid:17)(cid:3)
Catkin
Pendulous unisexual spike which bears naked
Spikelets pistillate or staminate flowers(cid:3)(cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:48)(cid:82)(cid:85)(cid:88)(cid:86)(cid:3)
Spikelets are small and few flowered spikes which are surrounded (cid:68)(cid:79)(cid:69)(cid:68)(cid:15)(cid:3)(cid:51)(cid:82)(cid:83)(cid:88)(cid:79)(cid:88)(cid:86)(cid:3)(cid:72)(cid:87)(cid:70)(cid:17)(cid:3)
at the base by two scales or glumes(cid:15) (cid:72)(cid:17)(cid:74)(cid:17)(cid:15) Family Gramineae
(= Poaceae).
Spadix
Spathe
Capitulum or Racemose head Spike with fleshy peduncle and having both
Sterile portion
The flattened peduncle called male and female flowers. It is surrounded by of spadix
as receptacle bears numerous a large green or coloured bract called spathe.
small sessile flowers called as The two types of flowers are separated by Male flowers
florets arranged in a centripetal downwardly directed sterile hair or neuter Neuter flowers
fashion. Florets can be ray florets flowers, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:38)(cid:82)(cid:79)(cid:82)(cid:70)(cid:68)(cid:86)(cid:76)(cid:68)(cid:15)(cid:3)(cid:36)(cid:85)(cid:88)(cid:80). Female flowers
(unisexual, ligulate, sessile, strap
shaped, petaloid, zygomorphic
flowers arranged on the periphery of Corymbose raceme
receptacle) or disc florets (tubular, The young flowers appear to be arranged like a
bisexual, sessile, actinomorphic corymb but in mature state, the longer pedicels
flowers occupying central position of the lower flowers do not bring them to the
on the receptacle). level of upper ones, (cid:72)(cid:17)(cid:74)(cid:17), mustard.
Compound Racemose
An indefinite or indeterminate inflorescence in which the peduncle is branched
repeatedly once or twice in a racemose fashion. It can be Panicle (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:39)(cid:72)(cid:79)(cid:82)(cid:81)(cid:76)(cid:91),
(cid:38)(cid:68)(cid:86)(cid:86)(cid:76)(cid:68)(cid:3)(cid:73)(cid:76)(cid:86)(cid:87)(cid:88)(cid:79)(cid:68)(cid:15) Compound corymb (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:37)(cid:85)(cid:68)(cid:86)(cid:86)(cid:76)(cid:70)(cid:68)(cid:3)(cid:82)(cid:79)(cid:72)(cid:85)(cid:68)(cid:70)(cid:72)(cid:68) var. (cid:69)(cid:82)(cid:87)(cid:85)(cid:92)(cid:87)(cid:76)(cid:86) (cauliflower),
Compound umbel (cid:72)(cid:17)(cid:74)., (cid:41)(cid:82)(cid:72)(cid:81)(cid:76)(cid:70)(cid:88)(cid:79)(cid:88)(cid:80)(cid:3)(cid:89)(cid:88)(cid:79)(cid:74)(cid:68)(cid:85)(cid:72), (cid:38)(cid:82)(cid:85)(cid:76)(cid:68)(cid:81)(cid:71)(cid:85)(cid:88)(cid:80)(cid:3)(cid:86)(cid:68)(cid:87)(cid:76)(cid:89)(cid:88)(cid:80) etc., Compound
spike (cid:72)(cid:17)(cid:74)., (cid:36)(cid:80)(cid:68)(cid:85)(cid:68)(cid:81)(cid:87)(cid:75)(cid:88)(cid:86), wheat, Compound spadix (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:38)(cid:82)(cid:70)(cid:82)(cid:86), date palm or
Compound capitulum (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:40)(cid:70)(cid:75)(cid:76)(cid:81)(cid:82)(cid:83)(cid:86), (cid:54)(cid:83)(cid:75)(cid:68)(cid:72)(cid:85)(cid:68)(cid:81)(cid:87)(cid:75)(cid:88)(cid:86).
Cymose Compound spadix Compound
of coconut umbel
A determinate inflorescence where main axis (peduncle) terminates into a flower
and further growth takes place by lateral branches. The arrangement of flowers
is basipetal ((cid:76)(cid:17)(cid:72)(cid:17), younger towards the base and older towards the apex) or
centrifugal, ((cid:76)(cid:17)(cid:72)(cid:17), younger towards the periphery and older towards the centre). It
is of following types:
(i) Uniparous or monochasial cyme
A single lateral branch arises from the peduncle of old flower which terminates in a
flower. The lateral branch also terminates in a flower. It is of two types: (a) Helicoid
cyme – All the flowers are borne on the same side forming a sort of helix, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)
(cid:39)(cid:85)(cid:82)(cid:86)(cid:72)(cid:85)(cid:68)(cid:15)(cid:3)(cid:37)(cid:72)(cid:74)(cid:82)(cid:81)(cid:76)(cid:68)(cid:15)(cid:3)(cid:48)(cid:92)(cid:82)(cid:86)(cid:82)(cid:87)(cid:76)(cid:86). (b) Scorpioid cyme - Flowers are alternately borne Helicoid cyme
on both the sides, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:55)(cid:72)(cid:70)(cid:82)(cid:80)(cid:68)(cid:15)(cid:3)(cid:53)(cid:68)(cid:81)(cid:88)(cid:81)(cid:70)(cid:88)(cid:79)(cid:88)(cid:86)(cid:15)(cid:3)(cid:43)(cid:72)(cid:79)(cid:76)(cid:82)(cid:87)(cid:85)(cid:82)(cid:83)(cid:76)(cid:88)(cid:80).
10 MTBIOLOGY TODAY | MAY ‘16
(ii) Biparous or dichasial cyme
The main axis terminates in a flower. A pair of lateral
branches arise below the terminal flower which too,
terminate into a flower. The process is repeated several
times, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:44)(cid:91)(cid:82)(cid:85)(cid:68), (cid:54)(cid:68)(cid:83)(cid:82)(cid:81)(cid:68)(cid:85)(cid:76)(cid:68), (cid:39)(cid:76)(cid:68)(cid:81)(cid:87)(cid:75)(cid:88)(cid:86), jasmine, etc.
(iii) Multiparous or polychasial cyme
More than two lateral branches continue the growth
of inflorescence when the parent axis ends in a
flower, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:43)(cid:68)(cid:80)(cid:72)(cid:79)(cid:76)(cid:68)(cid:15)(cid:3)(cid:38)(cid:68)(cid:79)(cid:82)(cid:87)(cid:85)(cid:82)(cid:83)(cid:76)(cid:86).
(iv) Cymose head Dichasial cyme Polychasial cyme Cymose head
of Dianthus of Hamelia of Acacia
Sessile or subsessile flowers are borne centrifugally
around a receptacle, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:36)(cid:79)(cid:69)(cid:76)(cid:93)(cid:93)(cid:76)(cid:68)(cid:15)(cid:3)(cid:36)(cid:81)(cid:87)(cid:75)(cid:82)(cid:70)(cid:72)(cid:83)(cid:75)(cid:68)(cid:79)(cid:88)(cid:86)(cid:3)(cid:70)(cid:68)(cid:71)(cid:68)(cid:80)(cid:69)(cid:68)(cid:15)(cid:3)(cid:36)(cid:70)(cid:68)(cid:70)(cid:76)(cid:68).
(v) Scapigerous head
The leafless flowering axis known as scape bears clusters of flowers that form a head which is covered by spaths,
(cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:36)(cid:79)(cid:79)(cid:76)(cid:88)(cid:80)(cid:3)(cid:70)(cid:72)(cid:83)(cid:68).
Hypanthodium
The receptacle (peduncle) is fleshy and forms hollow structure with an apical opening (orifice) guarded by hairy
structures. Three types of flowers develop on the inner surface of the receptacle.
The female flowers are towards the base, male flowers are towards the orifice and the short styled sterile female
flowers (gall flowers) are present in between, (cid:72)(cid:17)(cid:74)., (cid:41)(cid:76)(cid:70)(cid:88)(cid:86)(cid:3)(cid:85)(cid:72)(cid:79)(cid:76)(cid:74)(cid:76)(cid:82)(cid:86)(cid:68) (peepal), (cid:41)(cid:76)(cid:70)(cid:88)(cid:86)(cid:3)(cid:69)(cid:72)(cid:81)(cid:74)(cid:75)(cid:68)(cid:79)(cid:72)(cid:81)(cid:86)(cid:76)(cid:86) (banyan), (cid:41)(cid:76)(cid:70)(cid:88)(cid:86)(cid:3)
(cid:70)(cid:68)(cid:85)(cid:76)(cid:70)(cid:68)(cid:3)(fig).
Hypanthodium of fig
Special Inflorescence
Verticillaster Cyathium
A modified condensed The inflorescence looks like a flower. The bracts or
dichasial cyme like the involucre become fused to form a cup shaped
inflorescence in which two structure. The inflorescence contains pedicellate,
whorls of 3 to 9 flowers achlamydeous, unisexual flowers of both the
are borne in dichasial cyme types, male and female. The cup encloses a single
Cyathium of Euphorbia
like manner on either side female flower surrounded by a large number of
of a node, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:50)(cid:70)(cid:76)(cid:80)(cid:88)(cid:80)(cid:3) Verticillaster male flowers. (cid:40)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:40)(cid:88)(cid:83)(cid:75)(cid:82)(cid:85)(cid:69)(cid:76)(cid:68)(cid:3)(cid:83)(cid:88)(cid:79)(cid:70)(cid:75)(cid:72)(cid:85)(cid:85)(cid:76)(cid:80)(cid:68).
inflorescence
(cid:86)(cid:68)(cid:81)(cid:70)(cid:87)(cid:88)(cid:80). of Ocimum Cyathium of Euphorbia
Mixed
Two or more types of inflorescence get mixed up. It is of following types: (i) Mixed panicle (cid:72)(cid:17)(cid:74)., (cid:47)(cid:76)(cid:74)(cid:88)(cid:86)(cid:87)(cid:85)(cid:88)(cid:80)(cid:3)(cid:89)(cid:88)(cid:79)(cid:74)(cid:68)(cid:85)(cid:72),(cid:3)(ii) Panicle
of spikelets, (cid:72)(cid:17)(cid:74)., (cid:50)(cid:85)(cid:92)(cid:93)(cid:68)(cid:3)(cid:86)(cid:68)(cid:87)(cid:76)(cid:89)(cid:68) (rice), (iii) Corymb of capitula (cid:72)(cid:17)(cid:74)., (cid:36)(cid:74)(cid:72)(cid:85)(cid:68)(cid:87)(cid:88)(cid:80)(cid:3)(cid:70)(cid:82)(cid:81)(cid:92)(cid:93)(cid:82)(cid:76)(cid:71)(cid:72)(cid:86), (iv) Mixed spadix (cid:72)(cid:17)(cid:74)., (cid:69)(cid:68)(cid:81)(cid:68)(cid:81)(cid:68)
and (v) Thyrsus (cid:72)(cid:17)(cid:74). grapevine.
(cid:115)(cid:0) Capitulums are of two types (cid:89)(cid:76)(cid:93)., homogamous and heterogamous :
(cid:115)(cid:0) Homogamous head – The head/capitulum consists of only one type of florets (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:61)(cid:76)(cid:81)(cid:81)(cid:76)(cid:68)(cid:15)(cid:3)(cid:38)(cid:75)(cid:85)(cid:92)(cid:86)(cid:68)(cid:81)(cid:87)(cid:75)(cid:72)(cid:80)(cid:88)(cid:80) – all ray
florets; (cid:57)(cid:72)(cid:85)(cid:81)(cid:82)(cid:81)(cid:76)(cid:68)(cid:15)(cid:3)(cid:49)(cid:82)(cid:87)(cid:82)(cid:81)(cid:76)(cid:68) – all disc florets.
(cid:115)(cid:0) Heterogamous head – The head/capitulum consists of different types of florets (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:55)(cid:85)(cid:76)(cid:71)(cid:68)(cid:91)(cid:15)(cid:3)(cid:43)(cid:72)(cid:79)(cid:76)(cid:68)(cid:81)(cid:87)(cid:75)(cid:88)(cid:86)(cid:15)(cid:3)(cid:38)(cid:82)(cid:86)(cid:80)(cid:82)(cid:86). In
the heterogamous heads, ray florets are towards the periphery and disc florets are at the centre of the inflorescence. The
inflorescence becomes conspicuous and attractive due to the brightly coloured ray florets.
(cid:115)(cid:0) Head inflorescence (or capitulum) is considered to be the highly evolved type of inflorescence because there is:
– Economy of biological materials
– Enhancement of attraction due to aggregation of florets
– Maximum protection of flowers is ensured
– A single visit of the insect can pollinate many flowers
MTBIOLOGY TODAY | MAY ‘16 11
FLOWER
It is a specialised condensed shoot meant for carrying out the sexual reproduction. It bears floral leaves and gives rise to
seeds and fruits. The study of flowers is called anthology.
Stamen is the male reproductive part Carpel Carpel or female reproductive part forms
of a flower. It is made up of two parts, Stigma the innermost whorl of a flower. The free
Stamen
a stalk like filament and a knob like occurring unit of gynoecium is called
Style
terminal anther. Each anther has two pistil, which consists of basal swollen
Anther
lobes which are attached at the back Ovary ovary, a stalk like style and a terminal
Filament
by a sterile band called connective. receptive part called stigma.
They constitute the upper
accessory whorl of floral
organs called corolla which is
brightly coloured to attract
insects for pollination. In a
petal, the lower part is usually
narrow and is termed as claw
whereas the expanded portion Petal Sepal
of the petal is called limb.
They constitute the lower accessory
whorl of mostly green, flattened
Thalamus is a modified branch, that Ovule or foliaceous floral organs called
represents the axis of the floral whorls calyx which is mainly meant for
with undeveloped or suppressed Thalamus protecting other floral parts in
internodes between them. the bud condition.
(cid:115)(cid:0) In some flowers, the thalamus becomes elongated showing distinct nodes and internodes, (cid:72)(cid:17)(cid:74)., in (cid:42)(cid:92)(cid:81)(cid:68)(cid:81)(cid:71)(cid:85)(cid:82)(cid:83)(cid:86)(cid:76)(cid:86), (cid:38)(cid:68)(cid:83)(cid:83)(cid:68)(cid:85)(cid:76)(cid:86),
etc.
(cid:115)(cid:0) A floral bud like a vegetative bud is either terminal or axillary in position.
(cid:115)(cid:0) Arrangement of sepals, petals, stamens and pistil, etc., on the thalamus is the same as that of the leaves on the stem or
the branch, (cid:76)(cid:17)(cid:72)., alternate, opposite or whorled.
e Bisexual Pistillate
b
n Both the essential organs are present Only female flowers are present
a
c
r Unisexual
e Only one of the two
w
o Neuter essential organs is present Staminate
fl Both the essential organs are absent Only male flowers are present
A

A plant can be (i) monoecious - if male and female flowers develop on the same plant (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)maize, castor or (ii) dioecious - if
male and female flowers borne on separate plants (cid:72)(cid:17)(cid:74)., mulberry, date palm.
(cid:115)(cid:0) When male and bisexual flowers are present on the same plant it is called andromonoecious (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:57)(cid:72)(cid:85)(cid:68)(cid:87)(cid:85)(cid:88)(cid:80).
(cid:115)(cid:0) When female and bisexual flowers are present on the same plant it is called gynomonoecious (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)plants with
heterogamous head inflorescence in Family Asteraceae.
FLORAL SYMMETRY
The arrangement of floral organs around the axis of a flower is known as floral symmetry. The shoot on which the flower is
borne is called mother axis. The side of the mother axis is posterior while the side of the bract is anterior. In terminal flowers,
a distinction into anterior and posterior sides is absent.
12 MTBIOLOGY TODAY | MAY ‘16
Zygomorphic flower
It can be divided into two equal
halves by only one vertical
division, (cid:72)(cid:17)(cid:74)(cid:17), pea, (cid:50)(cid:70)(cid:76)(cid:80)(cid:88)(cid:80)
On the basis of
floral symmetry
Actinomorphic flower Asymmetrical flower
It can be divided by any vertical plane It cannot be divided into
into two equal and similar halves, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3) two equal halves by any
mustard, (cid:38)(cid:68)(cid:87)(cid:75)(cid:68)(cid:85)(cid:68)(cid:81)(cid:87)(cid:75)(cid:88)(cid:86)(cid:3)(cid:85)(cid:82)(cid:86)(cid:72)(cid:88)(cid:86). vertical plane, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:38)(cid:68)(cid:81)(cid:81)(cid:68).
Heteromerous Isomerous
Number in all the whorls is neither Whorls have equal number of parts or number in one whorl is multiple of
On the basis of number
the same nor any multiple. the number of other whorl.
of floral parts It can be bimerous (floral part in 2 or multiple of 2), trimerous (floral parts
in 3 or multiple of 3), tetramerous (floral parts in 4 or multiple of 4) or
pentamerous (floral parts in 5 or multiple of 5).
Floral phyllotaxy
Floral organs are borne on the thalamus either in spirals (acyclic or spiral, (cid:72)(cid:17)(cid:74)., (cid:48)(cid:68)(cid:74)(cid:81)(cid:82)(cid:79)(cid:76)(cid:68)(cid:15)(cid:3)(cid:49)(cid:92)(cid:80)(cid:83)(cid:75)(cid:68)(cid:72)(cid:68)), whorls (cyclic, (cid:72)(cid:17)(cid:74)., (cid:51)(cid:72)(cid:87)(cid:88)(cid:81)(cid:76)(cid:68))
or with some organs in spirals and other organs in whorls (spirocyclic or hemicyclic, (cid:72)(cid:17)(cid:74)., (cid:53)(cid:68)(cid:81)(cid:88)(cid:81)(cid:70)(cid:88)(cid:79)(cid:88)(cid:86)).
BRACTS
Bract is a small leaf like structure present on the peduncle which bears a flower in its axil. The floral buds are usually protected
by the bracts. Flower with a bract is described as bracteate and the flower without a bract is known as ebracteate.
Types
Foliaceous Petaloid Epicalyx Involucre
of bract
Leaf like, Petals-like large, One or more whorls of bracteoles A large number of bracts
expanded coloured bracts(cid:3)(cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3) are found at the base of calyx, form compact one or more
green bract (cid:37)(cid:82)(cid:88)(cid:74)(cid:68)(cid:76)(cid:81)(cid:89)(cid:76)(cid:79)(cid:79)(cid:72)(cid:68)(cid:15)(cid:3)(cid:40)(cid:88)(cid:83)(cid:75)(cid:82)(cid:85)(cid:69)(cid:76)(cid:68)(cid:3) (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)china rose, strawberry. whorls around a flower or an
(cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:36)(cid:71)(cid:75)(cid:68)(cid:87)(cid:82)(cid:71)(cid:68)(cid:15)(cid:3) inflorescence, (cid:72)(cid:17)(cid:74)., sunflower.
(cid:42)(cid:85)(cid:82)(cid:86)(cid:86)(cid:68)(cid:81)(cid:71)(cid:85)(cid:68)(cid:17)
Scaly Spathy Glumes
A membranous small A large modified The bracts found on the
bract present at the bract which encloses rachilla of spikelets. They
base of involucral spadix inflorescence may be sterile glumes or
bract, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)sunflower totally or partially (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3) fertile glumes (lemma),
(cid:36)(cid:79)(cid:82)(cid:70)(cid:68)(cid:86)(cid:76)(cid:68)(cid:15)(cid:3)(cid:48)(cid:88)(cid:86)(cid:68)(cid:15)(cid:3)etc(cid:17) (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:50)(cid:85)(cid:92)(cid:93)(cid:68)(cid:3)(cid:86)(cid:68)(cid:87)(cid:76)(cid:89)(cid:68).
Calyx and corolla together constitute accessory floral whorls. Depending upon the presence or absence of these whorls flower
can be
(i) Achlamydeous : Accessory floral whorls are absent (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:51)(cid:76)(cid:83)(cid:72)(cid:85)(cid:17)
(ii) Monochlamydeous : Only one accessory whorl (either calyx or corolla) or perianth (a collective term given to a group of
undifferentiated calyx and corolla), is present (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:51)(cid:82)(cid:79)(cid:92)(cid:74)(cid:82)(cid:81)(cid:88)(cid:80) (Polygonaceae), onion (Liliaceae).
(iii) Dichlamydeous : Both the accessory whorls are present (cid:72)(cid:17)(cid:74)(cid:17)(cid:15) (cid:43)(cid:76)(cid:69)(cid:76)(cid:86)(cid:70)(cid:88)(cid:86)(cid:3)(cid:85)(cid:82)(cid:86)(cid:68)(cid:16)(cid:86)(cid:76)(cid:81)(cid:72)(cid:81)(cid:86)(cid:76)(cid:86)(cid:17)
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CALYX
Calyx is the outermost whorl made up of sepals. It may be polysepalous (with free sepals) or gamosepalous (with fused sepals).
On the basis
of duration
Caducous Deciduous Persistent
Sepals fall off just after opening the Sepals fall off along with petals just Sepals remain attached with the ripe fruit,
bud, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15) (cid:36)(cid:85)(cid:74)(cid:72)(cid:80)(cid:82)(cid:81)(cid:72)(cid:15)(cid:3)(cid:51)(cid:68)(cid:83)(cid:68)(cid:89)(cid:72)(cid:85)(cid:3)etc. after fertilisation, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15) mustard. (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:51)(cid:76)(cid:86)(cid:88)(cid:80)(cid:15)(cid:3)(cid:50)(cid:70)(cid:76)(cid:80)(cid:88)(cid:80), Family Solanaceae.
Pappus
SpinouHsooded Sepals modified
into hairy structure
In (cid:36)(cid:70)(cid:82)(cid:81)(cid:76)(cid:87)(cid:88)(cid:80), one
which helps in
of the sepals is
dispersal of fruits,
modified into a
(cid:72)(cid:17)(cid:74)(cid:17)(cid:15) sunflower.
hood which covers
the whole flower.
Leafy and petalloid
Modification In (cid:48)(cid:88)(cid:86)(cid:86)(cid:68)(cid:72)(cid:81)(cid:71)(cid:68), one of
of sepals the sepals is modified
into a large leaf-like
coloured structue.
In (cid:47)(cid:68)(cid:85)(cid:78)(cid:86)(cid:83)(cid:88)(cid:85), from the
base of one of the In (cid:55)(cid:85)(cid:68)(cid:83)(cid:68), the calyx is
sepals arises a tubular persistent and modified
outgrowth called spur. into two spines.
Spurred Spinous
COROLLA
Corolla is the second whorl of a flower made up of petals. It may be polypetalous (petals free) or gamopetalous (petals
fused).
Cruciform Campanulate
Four free clawed petals are arranged Corolla is bell-shaped, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:51)(cid:75)(cid:92)(cid:86)(cid:68)(cid:79)(cid:76)(cid:86)
diagonally or in the form of a cross, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)
mustard, candytuft, etc.
a
oll Papilionaceous
r
o
c Five unequal or irregular petals are arranged like a butterfly.
Caryophyllaceous us The posterior large bilobed petal called standard or vexillum,
Corolla consists of five petals with distinct o
limbs and claws. The claw and the limb of al overlaps the two smaller lateral petals named wings or alae. The
et latter overlap the two anterior petals, which are fused laterally
each petal remain more or less at right yp by the upper anterior margins to form a boat shaped structure
angle to each other, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:39)(cid:76)(cid:68)(cid:81)(cid:87)(cid:75)(cid:88)(cid:86)(cid:17) ol called keel or carina. It is the characteristic of sub-family
p
f Papilionaceae, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15) pea, bean etc.
o
s
e
p
y
Rosaceous T
Five or more sessile or shortly clawed
petals are bent horizontally like a
saucer, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:53)(cid:82)(cid:86)(cid:68)(cid:3)(cid:76)(cid:81)(cid:71)(cid:76)(cid:70)(cid:68)(cid:3)(rose).
14 MTBIOLOGY TODAY | MAY ‘16
Infundibuliform
SpinouTsubular
Corolla is funnel-
Corolla is tubular shaped, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:39)(cid:68)(cid:87)(cid:88)(cid:85)(cid:68)
or cylindrical, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)
central florets
of sunflower
Rotate or wheel shaped
Tube of the corolla is
Ligulate orS sptirnaopu-sshaped
narrow and short and the
The upper part of corolla limbs are at right angles
is flattened like a strap to the tube,(cid:3)(cid:72)(cid:17)(cid:74)., brinjal
with the lower part
forming a short-tube, (cid:72)(cid:17)(cid:74)(cid:17),
Types of
outer florets of sunflower
gamopetalous
Salver shaped or hypocrateriform
corolla
PersonaStpei nooru msasked
Tubular corolla with spreading
Corolla is bilabiate but lobes, (cid:72)(cid:17)(cid:74)(cid:17), (cid:38)(cid:79)(cid:72)(cid:85)(cid:82)(cid:71)(cid:72)(cid:81)(cid:71)(cid:85)(cid:82)(cid:81)
the lips are so near to
each other as to close
the mouth of the corolla,
(cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:36)(cid:81)(cid:87)(cid:76)(cid:85)(cid:85)(cid:75)(cid:76)(cid:81)(cid:88)(cid:80)
Corolla is divided into two Corolla is like bell or inverted
lips-the upper lip and lower cup, (cid:72)(cid:17)(cid:74)(cid:15)(cid:3)(cid:38)(cid:68)(cid:80)(cid:83)(cid:68)(cid:81)(cid:88)(cid:79)(cid:68)
lip with the mouth gaping
Campanulate
wide open, (cid:72)(cid:17)(cid:74)., (cid:50)(cid:70)(cid:76)(cid:80)(cid:88)(cid:80)
Bilabiate
AESTIVATION
The mode of arrangement of sepals or petals with respect to one another in the floral bud is termed as aestivation.
Quincuncial
Aestivation of 5 parts,
Imbricate
where two are exterior,
Aestivation of five
two interior and the
parts, where one is Valvate
fifth is having one
exterior, one is interior Margins of adjacent
margin exterior and
and rest three are sepals or petals or tepals
the other interior.
having one margin just touch each other
exterior and without any overlapping,
other interior. (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)(cid:37)(cid:85)(cid:68)(cid:86)(cid:86)(cid:76)(cid:70)(cid:68)(cid:17)
Types of
aestivation
Descending
imbricate or vexillary Twisted or contorted To know about
One margin of each petal
The standard petal is Seven kingdom
overlaps the margin of
large and overlaps the
an adjacent petal and classification go to
two wing petals which
in turn overlap the keel the other margin being page no. 83
petals (cid:72)(cid:17)(cid:74)(cid:17)(cid:15) sub-family overlapped by margin of
another adjacent petal, (cid:72)(cid:17)(cid:74)(cid:17)(cid:15)(cid:3)
Papilionaceae.
(cid:43)(cid:76)(cid:69)(cid:76)(cid:86)(cid:70)(cid:88)(cid:86)(cid:3)(cid:85)(cid:82)(cid:86)(cid:68)(cid:16)(cid:86)(cid:76)(cid:81)(cid:72)(cid:81)(cid:86)(cid:76)(cid:86)(cid:17)
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