एक सर्वसमावेशक ब्लॉग

Friday 2 December 2022

9. Morphology of Flowering Plants -

Part 01 - ROOT

Angiosperms :

Angiosperms are one of flowering plants from phanerogams.

Types of Angiosperms [on the basis of habitat] :

Hydrophytes - Growing in aquatic habitat e.g. H ydrilla
Xerophytes - Growing in regions with scanty or no rainfall like desert e.g. Opuntia
Psammophytes - Growing in sandy soil e.g. Elymus
Lithophytes - Growing on rock e.g. Couchidium
Halophytes - Growing in saline soil e.g. Mangroove plants like Rhizophora

In angiosperms seed germinates under favourable environmental conditions and produces a seedling which develops into a new plant.

Morphology :

Morphologically plant shows vegetative structures like - root, stem, leaf and reproductive structures such as flowers, fruits and seeds.

Root :

Root is descending axis of plant body which is positively geotropic and hydrotropic but negatively phototropic and aerotropic.
Root grows beneath the soil surface towards gravity.
Roots are generally non-green, cylindrical and without nodes and internodes.

Typical Root Structure :

A typical root has different regions :-

Root cap
Region of cell division or meristematic region
Region of elongation
Region of root hair / absorption/piliferous zone
Region of cell maturation or differentiation

1. root cap :

A parenchymatous multicellular structure in the form of cap, present over young growing root apex is known as root cap.
Cell of root cap secrete mucilage for lubricating passage of root through the soil.
Cells of root cap show presence of starch granules which help in graviperception and geotropic movement of root.
Usually single root cap is present in plants. But in plants like Pandanus or screw pine multiple root caps are present.
In hydrophytes root caps are replaced by root pocket e.g. Pistia, Eichhornia etc.

2. region of cell division or meristematic region :

Due to presence of root cap the growing apex of root is subterminal in position.
The apex of the root is a growing point about 1 mm in length protected by root cap. This region is called as region of cell division or meristematic region.

3. Region of elongation :

The structure is developed by compactly arranged thin walled actively dividing meristematic cells.
These cells bring about longitudinal growth of root.
It is followed by Region of elongation. This region of cells is present just above zone of cell division.

4. A Region of root hair / absorption/piliferous zone :

The cells are newly formed and show rapid elongation to bring about increase in length of the root.
The cells help in absorption of mineral salts.
A Region of root hair / absorption/piliferous zone is made up of numerous hair like outgrowths.

5. Region of cell maturation or differentiation :

The epiblema or piliferous layer produces tubular elongated unicellular structures known as root hair.
They are in close contact with soil particles and increase surface area for absorption of water.
Root hair are short lived or ephimeral and are replaced after every 10 to 15 days.
Region of cell maturation or differentiation is major portion of root is developed by this region.
The cells of this region are quite impermeable to water due to thick walled nature.
The cells show differentiation and form different types of tissues. This region helps in fixation of plant and conduction of absorbed substances.
Development of lateral roots also takes place from this region.

Function of Root :

Roots carry out several functions which can be categorized into primary and secondary functions.
Primary functions of root are -

fixation or anchorage of plant body in the soil
absorption of water and minerals from soil and
conduction of absorbed materials up to the stem base etc.

Types of Root :

On the basis of origin, roots can be classified as -

Tap roots or true roots and
Adventitious roots.

a. Tap root :

The root which develops from the radicle of an embryo during seed germination is known as tap root or true root.
The main root is called as primary root; its branches of first order are called as secondary roots whereas branches of second order are called as tertiary roots e.g. Pea, Bean, Sunflower etc.
The main root with all its branches is known as tap root system.
Tap root system is commonly seen in dicotyledonous plants.

b. Adventitious roots :

A root that develops from any part other than radicle is known as adventitious root.
Such root may develop from the base of the stem, nodes or from leaves.
In monocots, radicle is short lived and from the base of stem a thick cluster of equal sized roots arise. This is adventitious root system. eg.Maize, Wheat, Sugarcane etc.
It is also known as fibrous root system as they look like fibre.
The growth of roots is superficial.
Adventitious root in some plants are used for vegetative propagation. eg. Euphorbia, Carapichea ipecacuanha (Ipecac) etc.

Modification of root :

When roots have to perform some special type of function in addition to or instead of their normal function they develop some structural changes. Such roots are called as metamorphosed roots.

Modifications of tap root
a. Food storage :

When tap root stores food it becomes swollen fleshy and also develops definite shape.
Main or primary root is the main storage organ but sometimes hypocotyl part of embryo axis also joins the main root.
Secondary roots remain thin. Stem in such cases remain reduced, discoid and leaves are radicle leaves.
On the basis of shape swollen tap roots are classified as -

Fusiform
Conical and
Napiform.

Fusiform root :

It is swollen in the middle
tapering towards both ends forming spindle shaped structure.
e.g. Radish (Raphanus sativus)

Conical root :

It is broad at its morphological base
narrows down towards its apex is called as conical root.
e.g. Carrot (Daucus carota)

Napiform root :

The base of root is highly swollen
almost spherical in shape and
abruptly narrows down towards its apex.
e.g. Beet (Beta vulgaris)

b. For Respiration : Pneumatophores or Respiratory Roots :

Halophytes are the plants which grow in -

saline swamps
marshy places and
salt lakes.

These plants produce special kind of roots called as pneumatophores or breathing roots.
The main root system of these plants do not get sufficient air for respiration as soil is water logged.
Due to this, mineral absorption of plant also gets affected.
To overcome this problem underground roots develop special roots which are negatively geotropic; growing vertically upward.
These roots are conical projections present around main trunk of plant.
The roots show presence of lenticels i.e. minute pores for gaseous exchange ( Pneuamatic - Hollow, phore - stalk)
e.g. Rhizophora, Avicennia, Sonneratia, H eritiera (ver. sundri) etc.

Modifications of Adventitious Roots :
a. Food storage :

Fibrous roots also show food storage like tap root.
The main difference is that fibrous root usually do not develop definite shape.
These roots are further classified as -

Simple tuberous
Fasciculated tuberous,
Beaded and
Nodulose roots.

Simple tuberous roots

become swollen and do not show definite shape.
They are produced singly.
The roots arise from nodes over the stem and penetrate into the soil.
E.g. sweet potato or shakarkand (I pomoea batatas).

Fasciculated tuberous root :

A cluster of roots arising from one point which becomes thick and fleshy due to storage of food is known as fasciculated tuberous root.
These clusters are seen at the base of the stem.
E.g.Dahlia, Asparagus, etc.

Beaded roots :

Beaded roots are also called as moniliform roots.
These roots are swellings at regular intervals like beads of a necklace.
e.g. Spinacia oleracea (Indian Spinach).

Nodulose roots

The cluster of long slender roots become enlarged at the tips forming nodules is known as nodulose roots.
E.g. Arrow (Maranta root) Amhaldi (Curcuma amada)

do you know :

A banyan tree growing in the Indian Botanical Garden, howrah (Kolkata) has nearly 1700 such prop roots.
The crown of tree has a large circumference.
The tree is about 200 years old.

b. For mechanical support :

1. Prop roots :

These roots arise from horizontal branches of tree like Banyan tree (Ficus benghalensis) and grow vertically downwards till they penetrate the soil.
These prop roots show secondary growth, become thick.
Act like pillars to provide mechanical support to the heavy branches.

2. Stilt roots :

These roots normally arise from a few lower nodes of a weak stem in some monocots shrubs and small trees.
They show obliquely downward growth penetrating soil and provide mechanical support to the plant.
In the members of family Poaceae, the plants like Maize, Jowar, Sugarcane etc. produce stilt root in whorl around the node.
These roots provide additional support to the plant body.
In Screwpine or Pandanus (Kewada), stilt roots arise only from the lower surface of obliquely growing stem for additional support.
These roots show multiple root caps.

3. Climbing roots :

Different climbers with weak stem produce roots at their nodes by means of which they attach themselves to support and there by raise themselves above the ground
e.g. Betel leaf or Pan, black pepperor Piper nigrum (Kali Mirch), Pothos or money plant.

4. Clinging Roots :

These tiny roots develop along internodes, show disc at tips, which exude sticky substance.
This substance enables plant to get attached with walls of buildings.
They do not damage substratum.
e.g. English Ivy (Hedera helix).

5. Plank Roots/Buttresses :

Often develop at the base of large trees form plank like extensions around stem. e.g. Silk cotton, Pipal etc.

6. Buoyont roots :

Roots developed at the nodes of aquatic herbs like (Jussiaea repens), become highly inflated and spongy providing buoyancy and helping the plant to float.

c. For special functions :
1. Epiphytic roots :

Small epiphytic plants such as orchids growing on the branches of huge trees in dense rain forests and are unable to obtain soil moisture.
They produce specialized root to hang in the air.
The roots are provided with a spongy membranous absorbent covering of the velamen tissue.
The cells of velamen that absorb moisture from air.
A tissues are hygroscopic and have porous walls The roots may be silvery white or green but without root cap.
e.g. Vanda, Dendrobium etc.

2. Sucking roots or Haustoria :

Specialised microscopic sucking roots developed by parasitic plants to absorb nourishment from the host.
Viscum album is a partial parasite.
It develops haustoria which penetrate into xylem of host plant for absoptional food.
In Cuscuta reflexa or Dodder (Amarvel) haustoria penetrates vascular strand and suck food from phloem, water and minerals from xylem.
Cuscuta is leafless plant with yellow stem. It is a total parasite.

Part 02 - STEM

Stem :

The aerial part of the plant body is know as shoot system.
Stem is the main axis of this shoot system.
Stem is the ascending part of the plant body which develops from plumule and reproductive units and is differentiated into nodes and internodes.
It is usually positively photorophic, negatively geotropic and negatively hydrotropic.
It shows different types of buds (axillary, apical, accessory, etc.).
At nodes it produces dissimilar organs such as leaves and flowers and similar organs such as branches.
Young stem is green and capable of photosynthesis.
The primary functions of the stem are -

To produce and support branches, leaves, flowers and fruits;
conduction of water and minerals and
transportation of food to plant parts.

Modifications of stem :

Stem develops some modifications for additional or accessory functions. To perform such function stem shows different modifications :

a. Underground stem :

In some herbaceous plants stem develops below the soil surface called as underground stem.
Underground stem remains dormant during unfavourable condition and on the advent of favourable condition produces aerial shoots.
Underground stem is known to store food, helps in perinnation and vegetative propagation.

1. Rhizome :

It is prostrate dorsiventrally thickened and brownish in colour.
It grows either horizontally or obliquely beneath the soil.
Rhizome shows nodes and internodes, bears terminal and axillary buds at nodes.
Terminal bud under favourable conditions produces aerial shoot which degenerates at the end of favourable condition.
Growth of rhizome takes place with lateral buds such growth is known as sympodial growth.
e.g. Ginger (Zingiber officinale), Turmeric (Curcuma domestica), Canna etc.
In plants where rhizomes grows obliquely, terminals bud brings about growth of rhizomes. This is known as monopodial growth.
e.g. Nymphea, Nelumbo (Lotus), Pteris (Fern) etc.

2. Stem Tuber :

Special underground branches of stem at their tips become swollen due to storage of food material which is mostly starch.
Presence of distinct nodes but not internodes classifies tuber as stem.
At nodal part scale leaves are present with axillary buds commonly known as ‘eyes’.
‘Eyes’ can produce aerial shoots under favourable conditions.
Tubers are porpogated vegetatively e.g. Potato (Solanum tuberosum), Matalu (H elianthus tuberosus).
Tuber has two distinct ends viz. apical end and basal end called as rose and heel end respectively.
The number of nodes and eyes is more towards rose end.

3. Bulb :

Bulb is an underground spherical or pyriform stem.
Stem is highly reduced and discoid. It bears a whorl of fleshy leaves.
The scale leaves or fleshy leaves show concentric arrangement over the stem. These store food material.
Some outer scale leaves become thin and dry.
The reduced stem produces adventitious roots at its base.
The bulb is of different types Tunicated or layered bulb is made up of fleshy leaves arranged in concentric manner with outer dry scale leaf.
e.g. Onion.
In garlic the bulb is scaly or non-tunicatied.The fleshy scales are arranged in overlapping pattern.

4. Corm :

Corm is swollen underground spherical or subspherical vertically growing stem.
It is condensed structure with circular or ring like nodes.
Presence of axillary buds and scales is observed.
Adventitious buds are produced which help in vegetative propagation.
Adventitious roots are produced at lower part of stem
e.g. Colocasia (Arbi), Amorphophallus (Zamikand or Elephant foot) etc.

b. Sub aerial stem :

The stems are generally weak or straggling stems growing over the ground and need support for perpetuation.
Sometimes these stems are found to grow beneath the soil surface also. Thus they show contact with both air and soil.
Sub aerial stems are meant for perennation and vegetative propagation.
Scale leaves and axillary buds are present over stem surface. The later produces aerial shoots.

Different types of sub aerial shoots ::

1. Trailer :

The shoot spreads over the ground without intervals.
The branches are either flat i.e. procumbent or partly vertical i.e. documbent
e.g. Euphorbia, tridax etc.

2. Runner :

They are special narrow, prostrate or horizontal green branches which develop at the base of erect shoots known as crown.
Runners spread in all directions to produce new crowns with bunch of adventitious roots.
Presence of nodes with scale leaves and axillary buds is observed.
Eg. Cynodon (Lawn grass) Centella (Hydrocotyl), Oxalis etc.

3. Stolons :

The slender lateral branch arising from the base of main axis is known as stolon.
In some plants it is above ground (wild strawberry).
Primarily stolon shows upward growth in the form of ordinary branch, but when it bends and touches the ground terminal bud grows into new shoot and adventitious roots
e.g. Jasmine, Mentha etc.

4. Sucker :

It is non green runner like branch of stem. It which develops from underground base of roots.
It grows horizontally below soil and finally comes above the soil surface to produce a new plant.
Sucker can be termed as underground runner
eg. Chrysanthemum, Banana etc.

5. Offset :

These are one internode long runners in rosette plants at ground or water level.
Offset helps in vegetative propagation
e.g. Water hyacinth or Jal kumbhi (Eichhornia) and Pistia.

c. Aerial modification :

Stem or it's vegetative part modify to carry out specialized functions.
They develop various modifications for this purpose. Such modified stems are called as metamorphosed stems.

Different modifications :

1. Thorn :

It is modification of apical or axillary bud.
Thorn is hard pointed and mostly straight structure (except Bougainvillea where it is curved and useful for climbing)
It provides protection against browsing animals and also helps in reducing transpiration.
Apical bud develops into thorn in Carrisa whereas axillary bud develops into thorn in Duranta, Citrus, Bougainvillea, etc

2. Phylloclade :

Modification of stem into leaf like photosynthetic organ is known as phylloclade.
Being stem it possesses nodes and internodes.
It is thick, fleshy and succulent, contains mucilage for retaining water
e.g.Opuntia, cylindrical in Casuarina and ribbon like in Muehlenbeckia.

3. Cladodes :

The branches of limited growth i.e. one internode long and performing photosynthetic function are called as cladodes.
True leaves are reduced to spine or scales.
E.g.Asparagus.

4. Cladophylls :

These are leaf like structures bore in the axil of scale leaf.
It has floral bud and scale leaf in the middle i.e. upper half is leaf and lower half is stem.
e.g. Ruscus.

Stem tendrils :

Tendrils are thin, wiry, photosynthetic, leafless coiled structures.
They give additional support to developing plant.
Tendrils have adhesive glands for fixation.
Apical bud in Vitis quadrangularis gets modified in to tendril. The further growth is carried out by axillary bud. This branching pattern is termed dichotomous.
Axillary tendril in Passiflora axillary bud gets modified in tendril.
Extra axillary bud is the one which grows outside the axil. This bud in cucurbita gets modified in to tendril.
Normally floral buds are destined to produced flowers.But in plants like Antigonon they produce tendrils.

5. Bulbils :

In plants like Agave, Dioscorea etc. axillary bud becomes fleshy and rounded due to storage of food called as bulbil.
When it falls off it produces new plant and help invegetative propagation.

Part 03 - LEAF

Leaf :

Leaves are the most important appendages as they carry out photosynthesis and also help to remove excess amount of water from plant body.
Leaf develops from leaf primordium.
Leaf is dorsiventrally flattened lateral appendage of stem. It is produced at nodal region.
Leaf is thin, expanded and green due to presence of photosynthetic pigments. It shows exogenous origin.
Axil of leaf shows presence of axillary bud.
Leaf shows limited growth, does not show apical bud or a growing point.

1. Typical leaf structure :

It shows presence of three main parts-

Leaf base or Hypopodium,
Petiole or Mesopodium and
Leaf lamina/ blade or epipodium.

Leaf base :

The point by which leaf remains attached to stem is known as leaf base.
The nature of leaf base is varies in different plants.
It may be pulvinus (swollen), sheathing or ligulate etc.
In some plants leaves possess a pair of lateral outgrowths called as stipules.
The leaf with stipule is said to be stipulate and without stipule is exstipulate.
Stipules are normally green protective structure.

Petiole or mesopodium :

The part of leaf which connect leaf lamina with the leaf base is known as petiole of leaf.
A leaf with petiole is petiolate and a leaf without petiole is termed as sessile leaf.
Petiole helps lamina to get exposed to light and also helps in conduction.

Lamina or epipodium :

Large expanded, flat and green part of leaf.
The lamina surface plays important role in photosynthesis, gaseous exchange and transpiration.
The leaf is either dorsiventral or isobilateral.
Dorsiventral leaf is common in Dicots and isobilateral in Monocots.
Centric or cylindrical leaves are those in which both the surfaces of leaf cannot be distinguished distinctly.
Leaf lamina varies greately in shpe, margin and apex.

2. Leaf venation :

Arrangement of veins and veinlets in leaf lamina is known as venation.
Veins are responsible for conduction of water and minerals as well as food.
The structural framework of the lamina is developed by veins.

3. Types of leaf :

Based on incision of lamina leaves are of two main types. i.e.

simple and
compound.

The leaf with entire lamina is called simple leaf
Leaf in which lamina is divided into number of leaf lets called as compound leaf.

Types of Compound leaf :
a. Pinnately compound :

Leaflets are present laterally on a common axis called rachis, which represents the midrib of the leaf.

b. Palmately compound :

In which all the leaflets are attached at tip of petiole.

4. Modification of leaves :

Apart from photosynthesis leaf also performs transpiration gaseous exchange and perception of light for flowering.
However leaves may undergo modifications to perform several other functions.
As per the modification their are different types of leaves shown below.

a. Leaf spines:

Sometimes entire leaf is modified into spines (Opuntia) or margin of leaf becomes spiny (Agave) or stipule modifies into spine (Acacia) to check the rate of transpiration or to protect plant from grazing.
E.g. Zizyphus etc.

b. Leaf tendril:

In some weak stems for providing addtitional support; leaf, leaflet or other part modifies to produce thin, green, wiry, coiled structure called as leaf tendril.
It helps in climbing.

c. Leaf hooks:

In plants like Bignonia unguiscati (Cat’s nail) the terminal three leaflet get modified into three stiff curve and pointed hooks used to cling over bark of tree.

d. Phyllode:

When petiole of leaf becomes flat, green and leaf like it is called as phyllode.
In Acacia auriculoformis the normal leaf is bipinnately compound and falls off soon.
The petiole modifies itself into phyllode. It is xerophytic adaptation.

5. Phyllotaxy :

Arrangement of leaves on the stem and branches in a specific manner is known as phyllotaxy.
It enable leaf to get sufficient light.
Alternate Single leaf from each node E.g. Mango
Whorled Many leaves from each node E.g. Nerium
Opposite decussate - A pair of leaf from each node and the consecutive pair at right angle E.g. Calotropis
Opposite superposed - A pair of leaf from each node and the consecutive pair is arranged just above. E.g. Jamun

Part 04 -INFLORESCENCE

Inflorescence :

A specialised axis or branch over which flowers are produced or borne in definite manner is known inflorescence.
Inflorescence has two parts Penduncle and flowers.
All the flowers do not mature at same time. Chances of pollination increase and large number of flowers can be pollinated in single visit also makes the plant attractive.

Types of inflorescence :
a. Racemose :

Growth of peduncle is infinite or unlimited.
Apical bud is free for continuous growth.
Flowers are borne in acropetal succession. (Mature flowers at the base) Order of opening is centripetal.

b. Cymose :

Growth of peduncle is finite limited.
Apical meristem terminates into flower.
Flowers are borne in basipetal succession. (Mature flowers at the apex) Order of opening is centrifugal.

Part 05 - FLOWER AND SEED

Flower :

Flower is highly modified and condensed shoot meant for sexual reproduction.
On the basis of position a flower can be

axillary or
terminal.

In a typical flower, the thalamus (Consists of four compactly arranged nodes and three highly condenseed internodes.
From each node of thalamus, a circle or whorl of modified leaves is produced.
A flower may show presence of bract at base of pedicel or over the pedicel, such a flower is said to be bracteate.
A flower may not show presence of bract at base of pedicel, such a flower is said to be ebracteate.
A flower with pedicel is said to be pedicellate flower.
Without pedicel is called as sessile flower.
Flower with bilateral symmetry or Clitoria is called zygomorphic flower e.g. Sweet pea.
Flower with radial symmetry is called actinomorphic flower e.g. Sunflower.

Terminologies related to flower :

Complete : Presence of all four floral whorls.
Incomplete : Absence of any one of the floral whorl.
Perfect : Both androecium and gynoecium are present, also called as hermophrodite or bisexual flower.
Imperfect : Any one reproductive whorl is present also called as monophrodite or unisexual flower.
Unisexual : It can be either staminate (male)/ pistillate (female) flower
Neuter : When both reproductive whorls are absent, it is said to be neuter flower e.g. Ray floreti of sunflower.
Monoecious plant : Male and female reproductive flowers are borne on same plant. E.g. Maize.
Dioecious plant : Only one type of unisexual flowers are present on plant e.g. Date palm.

a. Insertion of floral whorls :

The position and arrangement of rest of the floral whorls with respect to gynoecium on the thalamus is known as insertion of floral whorls.
In a typical flower thalamus consist of four compactly arranged nodes and three internods.
Slope of thalamus decides insertion of floral whorls.

a. Hypogyny :

When the convex or conical thalamus is present in flower, ovary occupies the highest position while other floral parts are below ovary.
Ovary is said to be superior and flower is called as hypogynous flower.
E.g. Brinjal, Mustard, China rose etc.
It is denoted as G in floral formula.

b. Perigyny :

When cup shaped or saucer shaped thalamus is present in a flower, ovary and other floral parts occupy about same position.Such an ovary is said to be semi- superior or semi-inferior.
All floral whorls are at the rim of thalamus.
Flower is perigynous
e.g. Rose, Pea, Bean, etc.
It is denoted as G- in floral formula.

c. Epigyny :

When thalamus completely encloses ovary and may show fusion with wall; the other floral parts occupy superior position and ovary becomes inferior. Such flower is said to be epigynous flower,
e.g. Sunflower, Guava etc.
It is denoted as G - in floral formula.

b. Floral parts and their structure :

All floral parts develop from thalamus from different nodes.
From each node of thalamus circle or whorl of modified leaves is produced. Thalamus is called as torus or receptacle.
Thalamus is green in colour hence it can perform the process of photosynthesis.

1. Calyx (K) :

It is outermost floral whorl and individual members are known as sepals.
Sepals are usually green in colour and perform photosynthesis.
If all the sepals are united, the condition is gamosepalous and if they are free, the condition is called as polysepalous.
Gamosepalous calyx is found in china rose and polysepalous calyx is found in Brassica.
The main function of sepals is to protect inner floral parts in bud condition.
Sometimes sepals become brightly coloured (petaloid sepals) and attract insects for pollination e.g.Canna, Mussaenda etc.
Calyx i.e. Sepals modify into hairy structures called as pappus. Such calyx helps in dispersal of seeds or fruits. E.g. Sonchus.

2. Corolla (C):

It is second floral whorl from outer side and variously coloured.
The individual member is called as petal.
Petals may be sweet to taste, posses scent, odour, aroma or fragrance etc.
The condition in which petals are free is said to be polypetalous (e.g. Rose) and if they are fused it is called as gamopetalous (e.g. Datura).
The main function of corolla is to attract different agencies for pollination.

Perianth (P) :

Many times calyx and corolla remain undifferentiated. Such member is known as tepal.
The whorl of tepals is known as Perianth.

Do you know ?

Mango is polygamous plant and produces all types of flowers, staminate, bisexual and neuter.

Arrangement of sepals, petals or tepals :
Valvate :

Margins of sepals or petals remain either in contact or lie close to each other but do not overlap.
e.g. Calyx of Datura, Calotropis.

Twisted :

Margins of each sepal or petal is directed inwards and is overlapped.
While the other margin is directed outwards and overlap the margin of adjacent.
e.g. Corolla of China rose,Cotton etc.

Imbricate :

One of the sepals or petals is internal and is overlapped at both the margins.
One is external i.e. completely outside Rest of the members.
Overlap and get overlapped. e.g. Cassia, Bauhinia, etc.

Vexillary :

Corolla is butterfly shaped and consists of five petals.
Outermost and largest is known as standard or vexillum, two lateral petals are wings and two smaller fused forming boat shaped structures keel. e.g Pisum sativum

If all the tepals are free the condition is called as polyphyllous and if they are fused the condition is called as gamophyllous.
Sepaloid perianth shows green tepals while petaloid perianth brightly coloured tepals.
E.g. Lily, Amaranthus, Celosia, etc.
It protects other floral whorls.
Petaloid tepal helps in pollination and sepaloid tepals can perform photosynthesis.

Aestivation :

The mode of arrangement of sepals, petals or tepals in a flower with respect to the members of same whorl is known as aestivation.

Epicalyx :

It is an additional whorl of sepal like structures formed by bractiole which occurs on the outside of calyx.
These are 5-8 in number. It is a characteristic feature of family - Malvaceae.
They are protective in function. e.g. Ladies finger

3. Androecium (A):

It is third floral whorl from outer side.
Androecium is male reproductive part of a flower.
The individual member is known as stamen.
If all the stamens are free the condition is polyandrous and if they are fused. (Cohesion = Fusion between members of a similar whorl.
Adhesion = Fusion between members of dissimilar whorls)

Parts of Typical stamen :
1. Anther :

It is terminal in position.
Anther produces pollen grains.
It is usually bilobed bithecous, tetralocular/tetra sporangiate structure. e.g. Datura.
In some plants it is monotheocus (single lobed). Bilocular bisporangiate structure e.g. Hibiscus.

2. Filament :

It is a stalk of stamen and bears anther at its tip.
It raises anther to a proper height for easy dispersal of pollen grains.

3. Connective :

It is in continuation with the filament.
It is similar to mid rib and connects two anther lobes together and also with the filament.

Cohesion of stamens :

When stamens are united by filaments and anthers are free, the condition is adelphy.

Adhesion of stamens :

When the stamens are united to petals or tepals they are described as epipetalous e.g. Datura, Lily etc.

Syngeneious :

When anthers are united and filaments are free it is known as syngeny.
e.g. Sunflower

Synandrous :

Stamens are fused by both filaments and anthers in synandrous conditions e.g. Cucurbita.

4. Gynoecium (G):

It is the female reproductive part of flower and innermost in position. It is also known as pistil.
The individual member of gynoecium is known as carpel.
The number of carpels may be one to many.
If all the carpels are fused the condition is described as syncarpous and if they are free the condition is described as apocarpous.
The polycarpellary gynoecium can be -

bicarpellary (two carpels e.g. Datura)
tricarpellary (three carpels e.g. Cucurbita),
pentacarpellery (five carpels e.g. Hibiscus) and so on.

A typical carpel consists of three parts -

stigma
style and
ovary.

1. Stigma :

It is a terminal part of carpel which receives pollen grains during pollination.
It helps in germination of pollen grain.
Stigma shows variation in structure to suit the pollinating agent.

2. Style :

It is narrow thread like structure that connects ovary with stigma.

3. Ovary :

It is basal swollen fertile part of the carpel.
Ovules are produced in ovary on a soft fertile tissue called placenta.

Placentation :

The mode of arrangement of ovules on the placenta within the ovary is placentation.

Types of Placentation :

Marginal : Ovules are placed on the fused margins of unilocular ovary. e.g. Pea, Bean etc.
Axile : Ovules are placed on the central axis of a multilocular ovary. e.g. Chinarose, Cotton; etc
Parietal : Ovules are placed on the inner wall of unilocular ovary of multicarpellary syncarpus gynoecium. e.g. Papaya, Cucumber,
Basal : Single ovule is present at the base of unilocular inferior ovary. e.g. Sunflower, Rice, Wheat.

Free central :

Ovules are borne on central axis which is not attached to ovary wall. e.g. Fig.

Seed :

Seed is a reproductive unit that developed from fertilized mature ovule.
The seed is made up of -

seed coat and one or
two cotyledons.

Outer most covering of a seed is called seed coat, shows -

outer layers called testa and
inner tegmen.

Hilum is a scar on the seed coat through which seed attach to the fruit.
Embryo of a seed enclosed within seed coat.
Embryonal axis consists of -

radicle and
plumule.

The part of embryonal axis between cotyledon and plumule is epicotyl, while the part between cotyledons and radicle is hypocotyl.
The nutritive tissue in a seed called endosperm.

Part 06 - Study of some important families

Fabaceae :

Pea plant belongs to this family.
The plant is either tree shrub or herb.
The root shows root nodules.
Pea is a erect climber.
The leaves are pinnately compound arranged in alternate phyllotaxy.
The inflorescence is racemose type.
Flowers are bisexual and zygomorphic.
Calyx has five fused sepals (gamosepalous) arranged in imbricate aestivation.
Corolla has five free petals (polypetalous) arranged vexillary aestivation.
The petals are unequal in size.
The largest petal is vexillum, to small petal are wings and to smallest petals are keel.
Androecium has ten stamens arranged in diadelphous condition.
Gynoecium is monocarpellary.
Unilocular ovary is superior with many ovules on marginal placenta.
Ovary develops in legume type of fruit.
Seeds are non endospermic.

Solanaceae :

Plant is herb, shrub or small tree.
The root shows tap root system.
The stem is erect, woody and branched.
It is covered by hairy structures in some plants.
In potato it is underground tuber.
The leaves are simple arranged in alternate phyllotaxy with reticulate venation.
The inflorescence is Cymose type.
Flowers are solitary, bisexual and actinomorphic.
Calyx has five fused sepals (gamosepalous) arranged in valvate aestivation.
Corolla has five fused petals (gamopetalous) arranged valvate aestivation.
Androecium has five free epipetalous (adhesion) stamens.
Gynoecium is bicarpellary, syncarpous.
Bilocular ovary is superior with many ovules arranged in axile placentation on swollen placenta.
Ovary develops in berry or capsule type of fruit.
Seeds are endospermic.

Source from Internet

K P B