MORPHOLOGY OF FLOWERING PLANT

L No 5

Std : XI Science

Parts of a Typical Flowering Plant

Morphology of Root

Function of Roots • Roots are used for fixation, anchorage,

absorption of water & minerals

• For food storage

• After becoming green some roots perform photosynthesis

• In parasitic plants like cascuta. Adventitious root penetrate the host stem to obtain food & water

• Roots take part in vegetative reproduction

• Aerial roots absorb moisture from air.

• Prevents soil erosion

Types of Roots

Types of Roots Tap Root

• Develops from radicle of embryo

• Persistent primary root

• Grows deep in the soil.

• Always underground

• Secondary & tertiary root are developed from tap root

• Tap root is thick

Adventitious Root

• Develops from any other part than radicle

• Primary root is short lived

• Does not grow that deep in soil

• Underground & aerial

• Adventurous root develops from stem

• Adventitious root is comparatively thin.

Modifications of Tap Root • For food storage

Tap root becomes swollen & fleshy

Secondary root remains thin

Hypocotyl may also join in storing food

Stem is reduced & discoid in beginning & bears radical leaves

3 subtpes

Modifications of Tap Root • FUSIFORM ROOT Root is swollenin middle

part & tapers towards base & apex is called Fusiform root

Eg: Raddish

Modifications of Tap Root

• CONICAL ROOT

Broad at the base & gradually tapering towards apex is called conical root

Eg Carrot

Modifications of Tap Root

• NAPIFORM ROOT

Base of root is much swollen, almost spherical, tapers into narrow apex

Eg: Beet

Modifications of Tap Root • FOR RESPIRATION

Plants growing in swamps, marshy places, & salt lakes called halophytes & they develop special kind of roots called pneumatophores

Roots grow vertically upwards i.e. negatively geotropic& come out of soil in form of conical spikes

Large number around tree trunk & are provided with pores called lenticles

Modifications of Adventitious Roots

SIMPLE TUBEROUS ROOT

Roots become swollen & no definite shape

Always born singly

Roots arise from nodes of stem

Eg: Sweet potato/ shakarkand

FASCICULATED TUBEROUS ROOT

Roots of some plants become thick & fleshy due to storage of food

There are many tuberous roots

Roots arise from base of stem

Eg: Dahlia, Aspargus

FOR FOOD STORAGE

Modifications of Adventitious Roots

Prop Root

• Roots arise from horizontal branches of trees & grow till they penetrate soil

• Secondary growth occurs, become thick& gives mechanical support

• Eg : Banyan Tree

Stilt Root

• Roots arise from nodes

• They grow obliquely downwards & penetrate in soil

• Eg: maize, sugarcane, bajara, jowar

FOR MECHANICAL SUPPORT

Climbing Root

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Climbing plants like piper Produce roots from their Nodes by means of which they attach themselves to some support & climb over it. Eg: Money plant, Kali mirch, pan( beetle leaves)

Underground Stem Modification • RHIZOME

It is a prostrate, dorsiventral, thickened brownish stem which grows horizontally under surface of the soil

Shows distinct nodes & internodes

Possesses terminal bud

Rhizome remains dormant

Eg: ginger, turmeric, lotus, fern

Underground Stem Modification • STEM TUBER

They are swollen due to storage of food (carbohydrate like starch)

Tuber show nodes & internodes

Under favourable conditions ‘eyes’ sprout & produce aerial shoots

It helps in vegetative propagation

They do not produce adventitious root hence they differ from rhizome

Eg: potato

Underground Stem Modification • BULB

It is condensed, disc like underground stem, which does not store food

Overlapping scaly leaves present

Lower surface of stem produces adventitious roots

Some times have concentric rings are called tunicated bulb. Eg: onion

Sometimes they may partially overlap by their margins such bulbs are called scaly bulb. Eg: garlic

Underground Stem Modification

CORM

Corm is short, stout, fleshy upright & thickened underground stem

It bears many buds in the axils of scale leaves which develop inton daughter corms

At bases or even from sides of stem adventitious roots develop

It is condensed form of rhizome

Eg: Arbi, Zamikand

Sub Aerial Modification RUNNER

These are special, narrow, green,horizontal which develop at the base of erect shoots called crowns

They spread in different directions & bear new crowns above & adventitious roots below.

The nodes bear scale leaves & axillary bulbs

Eg: Lawn Grass, Oxalis

Sub Aerial Modification STOLON

Stolon is slender lateral branch that arises from base of main axis

Initially stolon hrows upwards like ordinary branch & thenb bends down & touches the soil where its terminal bud give rise to a new shoot & adventitious roots

Eg: Jasmine, mentha, strawberry & colocasia

Sub Aerial Modification Offset

It is commonly called the runner of aquatic plant

It is shorter & thicker than runner

It helps in vegetative propagation in aquatic plants

Eg: water hyacinth & Jalkumbhi & pistia

Sub Aerial Modification SUCKER

Sucker is a runner like non-green branch which develops from axil of scaleleaf in underground stem

It grows horizontally below the soil obliquely & produces green leaves to form aerial shoots]

The sucker can therefore be called underground runner

Eg: Chrysanthemum, Mint ( Pudina)

Aerial Modification Stem tendril

Axillary bud modifies to form thin, wiry & highly sensitive structure called tendril

It helps attach to itself to support & climb

They are found in plants with weak stem

The tendrils are leafless, coiled structures with sensitive adhesive glands for fixation

Eg:Passiflora, Cucurbita, antigonon

Aerial Stem Modification

THORN

Thorn is hard , pointed usually straight structure produced by modification of axillar bud

Leaves, branches & flowers are developed on thorns at the nodes indicating that is a modified stem

It provides protection against browsing animals

Citrus, Bouganvillae, Duranta, Carrisa etc.

Aerial Stem Modification PHYLLACODE/ CLADOPPHYLL

A stem which gets transformed into stem like structure

It is green Flat structure with distinct nodes & internodes

Eg: Opuntia, Muehlenbeckia

Aerial Stem Modification Cladode

These are green branches of limited growth which have taken up the function of photosynthesis

True leaves are reduced to scales or spines

Eg: Asparagus

Aerial Stem Modification Bulbils

When axillary bud becomes fleshy & rounded due to storage of food is called bulbil

It gets detached from the plant falls on ground & develops into new plant

Eg: Dioscorea

Characteristics of foliage leaf Leaf Base or hypodium

Petiole/ mesodium

Lamina/ leaf blade or Epipodium

Leaf Venation Reticulate Venation

• Veins are in bigger size

• Veins have network of branched veins

• 2 cotyledon

• Leaves break in indefinite shape

Parallel Venation

• Veins are comparatively smaller

• Veins run parallel

• One cotyledon

• Leaves break in definite shape

Simple Leaf

• Simple leaves are those in which single leaf blade or lamina is present

• Eg: mango, Peepal, Papaya

Compound Leaf Compound leaves are those in which the leaf

blade or lamina is divided into a number of segments known as leaflets or pinnae

The leaflet never bears axillary bud in their axil

Thet are of 2 types: A) Pinnately compund

Palmately compound

Types of Compound leaves Pinnately Compound Leaves

Leaflets are present laterally on common axis called rachis which remains midrib of the leaf

Four kinds:

a) Unipinnate

b) bipinnate

c) tripinnate

d) Decompound

Palmately Compound Leaves

Leaflets of the palmately compound leaves are attached at a common point i.e at the tip of petiolelike fingers of the palm

Five types

a) unifoliate

b) Bifoliate

c) Trifoliate

d) Quadrifoliate

e) Multifoliate

Modification Of Leaves Leaf Spines

In some xerophytic plants like Opuntia, the entire leaf gets modified into a small, stiff, pointed structure called spine to check transpiration.

Sometimes only a part of leaf such as stipules, get modified into spines, to protect plants from grazing animals

Eg: Zizypus, Acacia

Modification Of Leaf Leaf tendrils

In certain plants having weak stem, entire leaf or its part of it gets modified into a elongated, thin, cylindrical, coiled, wiry, sensitive structure known as tendril

These tendrils help the plant to climb up on some support

Modification Of Leaf Leaf Hooks

In Bignonia unguis-cati, the terminal 3 leaflets get modified into 3 leaflets get modified into 3 stiff curved & pointed hooks which looks like cat’s nail.

These hooks cling to bark of tree & help the plant for climbing.

Modification Of Leaf PHYLLODE

In some plants, petiole becomes flat, green & leaf like & performs photosynthesis which is known as phyllode

Phyllotaxy Phyllotaxy is the arrangement of leaves on the stem

& branches in some definite manner.

The main purpose of phyllotaxy is to provide sufficient light ot all leaves

INFLOROSCENCE A natural group (cluster) of flowers produced on a

special reproductive axis (peduncle) of a plant is called as infloroscence

When flower produced singly – solitary flower

Significance of Inflorescence It makes flowers more conspicuous & attractive

Therefore it attracts more pollinating agentslike birds & insects

Many flowers can be pollinated in single visit

Flowers open successively & not simultaneously.this elongates flowering period

It is on of the criteria for identification & classification of flowering plants*

Types of Inflorescence RACEMOSE/INDEFINITE INFLOROSCENCE

Flowers are arranged in acropetal succession on peduncle-i.e. older flower on lower axis mature earlier while flower at apex mature later

Flower arrangement is centripetal

Eg: Gulmohar, Caesalpinia

Types of Inflorescence CYMOSE/ DEFINITE INFLOROSCENCE

Flowers are arranged in basipetal succession i.e. older flower is at apex and younger flower is at the base. ( Central flower is oldest)

Flower arrangement is always centrifugal

Eg: Jasmine, Clerodendron

Parts of a typical Flower

Parts of a typical Flower Complete Flower: all 4 whorls

Incomplete Flower: Any one whorl absent

Unisexual flower: Any one essential whorl absent

Neuter: Both essential whorl absent

Monoecious Plants: Both type of unisexual flower

Dioecious Plants :Only 1 type of unisexual flower

Polygamous Plant: all flowers i.e. bisexual, staminate & neuter

SYMMETRY OF FLOWERS Actinomorphic Regular/Radial Symmetry Flower:

All floral whorls are can be divided into 2 equal halves from any plane eg: mustard, China rose

Zygomorphic Monosymmetrical or bilaterally Symmetry: Flower can be divided into 2 equal halves along one plane. Eg: pea, Ocimum

Assymetrical or irregular Flower: Flowers which cannot be divided into 2 equal halves eg: Canna

Fruits Parthenocarpic fruit: Fruits produced without

fertilization. ( seedless fruits). Eg: grapes, banana

True Fruit: Fruit produced exclusively from ovary. Eg: mango

False Fruit/ Pseudocarps: Any other floral part like thalamus or receptacle except ovary is called false fruit. Eg: apple & pear

TYPICAL PARTS OF FRUITS • True Fruit False fruit

Classification of Fruits

Classification of Fruits SIMPLE FRUIT

When ovary of a single flower develops into single fruit is called simple fruit.

Further divided to : A) Dry B) Fleshy fruit

Dry fruits are further divided into :

a) Dehiscent: eg: Legumes like peas

b) indehiscent; eg: Capsule like lady’s finger

Fleshy fruits are mostly indehiscent

Fleshy fruits are further divided into:

a)Drupe(1 seeded): eg: peach

b) Berry(many seeded): eg: berry like tomato

Classification of Fruits AGGREGATE FRUIT

A fruit which has developed from polycarpelllary apocarpous(carpels free from each other) gynoecium of a single flower is called aggregate fruit.

Eg: Custard Apple

Classification of Fruits COMPOSITE OR MULTIPLE FRUIT

A fruit develops from entire inflorescence.

In such fruits along with ovaries & other floral parts the peduncle also takes part in formation of fruit

Classified into 2 types: a) Sorosis: Eg: pineapple

b) Syconus : Eg: Fig

SEED • A seed is defined as a fertilized and

metamorphosed ovule containing an embryo enclosed in resistant protective coats.

STRUCTURE OF DICOT SEED • A typical dicot seed consists of seed coat made up

of 2 layers- outer thick & resistant layer is called testa while inner thin & membranous layer called tegmen

Structure of Monocot Seed

• In monocot seed coat & fruit wall are inseperable

• A thin layer lying around the grain is formrd of seed coat & fruit wall which is called hull

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