morphology of flowering plant of flowering plant... · 2020. 8. 3. · plant l no 5 std : xi...
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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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