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Kotakonda Sivakumar M.Sc. B.Ed. M.Phil Junior Lecturer
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INTERMEDIATE PUBLIC EXAMINATIONS

BOTANY(Practicals) – Question Paper

Time :3 Hours                                                                                                 Max Marks:30

 


 

1). Describe the vegetative and floral characters of the given twig ‘A’in technical terms. Draw labelled diagrams of the twig with inflorescence and LS of flower. Give floral diagram and floral formula. Identify it’s family.                                                                       6 Marks

2). Take T.S of the given material ‘B’. Stain, mount and leave the preparation for evaluation. Identify it and draw a well labelled diagram (Sector only). (No need to write identification characters).                                                                                                                6 Marks

3). Experiment ‘C’                                                                                                      6 Marks

            Cytology

            - Preparation of slide                                                                                       3 Marks

            - Identification of any one stage                                                                     1 Mark

            - Identification characters                                                                               1 Mark

            - Labelled diagram                                                                                          1 Mark

            Physiology                 

            - Performing the experiment                                                                           3 Marks

            - Writing the Aim, Principle, Observation

              and Inference (no need to write procedure and no

              need to draw diagram)                                                                                  3 Marks

                                                                                                                        (½  + 1 + 1+ ½)

4). Identify D. E, F, G, H given reasons.                                                                   5 Marks

            ( Diagram are not needed)

5). Record and Herbarium                                                                                          7 Marks

            Record                                                                                                                        5 Marks

            Herbarium                                                                                                       2 Marks

 

Aim: To observe and identify  the main phases of mitotic division in root apical meristematic cells  of onion.

Principle : Root apical meristems are to be collected at appropriate time and slides must be prepared using each meristem for observation under the microscope. During mitotic cycle, cells will be in various phases of division namely Interphase, prophase, metaphase, anaphase and telophase.

Observation: Prophase: chromatin appears in the form of long thread like structures .

Nucleolus is present . Nuclear membrane present.

Or

Metaphase: chromosomes placed at equatorial plate

Spindle apparatus present.

 

 

Aim: To demonstrate the phenomenon of Osmosis through uptake of water by potato tuber.

Principle: Plant cells absorb water through the process of Osmosis which is the movement of solvent molecules across a selectively permeable membrane. The movement of water molecules from outside into the cells is known as endosmosis while movement of water molecules from the cells to outside is called plasmolysis.

Observation and inference: After the required period, it could be ovserved that the trough in the potato cube becomes completely filled . The initial salst solution in the trough acts as the higher concentrated solution. Water molecules from the cells of the tuber surrounding the trough move outside into the trough due to plasmolysis thus raising the level of the solution. In turn, the cell sap becomes more concentrated due to loss of water from it. Consequently the solvent molecules from the external distelled water enter into the cells due to endosmosis. Thus a continuous osmotic gradient will be created from the external distilled water to the cell sap In several cell layers and from there into the salt solution in the trough. In this pathway, the cell membranes act as the selectively permeable membranes.

 

Aim: To demonstrate the phenomenon of stomatal transpiration from leaves by cobalt chloride paper method.

Principle: :Plants loose water in the form of vapour and this  is called transpiration. A major proportion of this water loss is through the minute openings called stomata present on the leaf surface. The amount of water given out depends on the number of stomata present.

Observation and Inference

At the end of required period, it could be observed that the color on the cobalt chloride paper light blue changes to light pink. This change in color first appears as small dots as time passes, becomes later and more conspicuous regions.

The Original color of the dry cobalt chloride paper is light blue in color. When the water vapour coming out through the stomata touches the paper, it absorbs the water molecules and the wet region turns light pinkish in color . As more and more water is given out, the pink areas become gradually larger.

 

Aim: Extraction, separation and indetification of leaf pigments through  paperchromatograhic paper.

Principle: The principle involved is partion chromatography based on counter current distribution. Suppose compounds A and B are two immiscible solvents taken in a caontainer.  If compound X is added . Part of it Xa dissolve in A  and the remaining Xb dissolve in B. Then the ration is Xa/Xb=aK  is called partion co-efficient. And a is the volume of A  to volume of B . Different substances will have different values  of K for a given combination of A and B.   

Observation and Inference: Four different colour rings appear on the filter paper

They are Carotene -reddish, xantophyll- yellowish, Chlorophyll a- bluish green, Chlorophyll b- dark green.

 

Mavaceae: Class: Dicotyledonae, Sub-class: Polypetalae, Series: Thalamiflorae, Order: Malvales, Family: Malvaceae.

 

Vegetative characters:

Habitat: Mesophyte, Ornamental.

Habit: Shrub

Stem: Aerial, erect, woody, green, cylindrical, solid, hairy.

Leaf: Cauline and ramal, simple, alternate, petiolate, stipulate, ovate, serrate, acuminate, reticulate  venation, stellate hairs.

 

Floral features:

Inflorescence: Axillary, cymose, solitary

Flower in General : Ebracteate, Bracteolate- called epicalyx. Pedicellate, complete, bisexual, actinomorphic, dichlamydeous, heterochlamydeous, pentamerous, hypogynous, cyclic.

Calyx: Sepals 5, gamosepalous, cup-shaped, valvate, persistent.

Corolla: Petals5, polypetalous, slightly connate ate the base and adnate to the base of staminal tube, twisted, red.

Androecium: Stamens numerous, united, monoadelphous, filaments fused to form staminal tube, the tube ends with anther bearing filaments, anthers basifixed, monothecous, reniform extrorse, dehiscence transeverse, pollen grains spiny. 

Gynoecium: Pentacarpellary, syncarpous, superior and pentalocular, ovary with numerous ovuls on axile plancentaion. Style teriminal ,pentafid,and passes through staminal tube  and capitate.

Floral Formula:

 

Identification characters.Stellate hairs, leaves simple, alternate and stipulate

Staments numerous, monadelphous , anthers reniform

Gynoecium pentacarpellary axile placentation.

 

 

 

 

Fabaceae: Class: Dicotyledonae, Sub-class: Polypetalae, Series: Calyciflorae, Order: Rosales, Family: Fabaceae,

Vegetative characters:

Habitat: Mesophyte

Habit: Annual herb

Stem: Aerial erect, cylindrical, herbaceous, branched

Leaf: cauline and ramal, leaf base is pulvinous, stipulate, unipinnately compound leaf, imparipinnate, alternate, petiolate, leaflets obovate, entire, reticulate ventation apex is mucronate.

Floral characters:

Inflorescence: Simple raceme

Flower in General Bracterate, bracteolate, pedicellate, complete, bisexual, zygomorphic, perigynous, petnmetous, dichlamydeous, heterochlamydeous, cyclic.

Calyx: sepals 5, gamosepalous slightly fuse at the base, valvate, odd sepal is anterior.

Corolla Petals 5 polypetalous, papilinaceous, aestivation descendingly imbricate, odd petal is posterior.

Androecium Stament 10 diadelphous (9)+1, anthers introrse, dithecous, basifixed, longitudinal dehiscence.

Gynoecium: Monocarpellary, unilocular, Half inferior , marginal placentation, style long bent at base, stigma simple  and hairy

Fruit: Legume

Seed: dicotyledons, non endospermic.

Floral formula:

Identification characters:

Compound leafe, pulvinous leaf base, papilionaceous corlloa, zygomorphic flower ,odd sepal anterior, descendigly imbricate aestivation of corlolla, diadelphous staments, moncarpellary, unilocular, marginal plancentation, fruit legume.   

 

 

 

 

 

 

Solanaceae: Class: Dicotyledonae, Sub-class: gamopetalae, Series: Bicarpetallatae,

Order: Polemoniales, family : solanaceae.

 

Vegetative characters:

Habitat: Mesophyte, wild.

Habit: Small shrub

Stem: Aerial, erect, herbaceous, cylindrical, green branched.

Leaf: Cauling and ramal, simple, alternate in the vegetative region but opposite in the flowering region, exstipulate, petiolate, ovate, acute, dentate, pinnately reticulate, adnation of petiole with the stem.

 

Floral characters:

Inflorescence: Terminal, cymose, solitary cyme.

Flower in general: Ebracteate, ebracteolate, pedicellate, bisexual, complste , actinomorphic, dichlamydeous, hterochlamydeous hypogynous, pentamerous, cyclic

Flower in detail

Calyx: Sepals 5, gamosepalous valvate aestivation, persistent.

Petals: petals5, white, gamopetalous, infunfibuliform, twisted aestivation.

Androecium: stament 5, epipetalous, anthers dithecous, introrse, basifixed, dehiscence longitudinal.

Gynoecium: Bicarpellary, syncarpous biloculat later become tetra locular due to formation of false septum. Ovary superior, swollen plancenta, axile placentation, ovary is oblique in postion due to the tilting of posterior carpel to the ritht and anterior carpel to left at an angle of 45. syle terminal and stigma capitate

Fruit : Septifragal

Floral formula

 

Identification characters;

Simple exstipulate Solitary cymose, inflorescne actinomorphic and hypogynous flower ,gamopetalous epipetalous, bicarpellary, tilting of carpl ,swollen placenta, axile placentaion.

Aerial Stem Modifications –Six types:

 

Type

Characters

Functions

Ex.

Tendrils

Wiry coiled, sensitive structures

Climbing

Passiflora ( axillary bud), Cissus (terminal bud

Thorns

Hard pointed structures

Protection

Bougainvellea (axillary bud)

Hooks

Curved, sensitive structures

Climbing

Hugonia(axillary buds) , Artabotrys ( apical bud)

Phylloclade

Green, sensitive structures

Photosynthesis

Opuntia, casuarina,

Cladode

Limited growth phylloclades

photosynthesis

Asparagus, Ruscus

Tuberous stem

Aerial stem store food materials

Storage of food

Knol khol,

Pseudobulb

Store food in internodes

storage

Bulbophyllum(epiphyte)

Bulbils

Condensed vegetative , floral buds.

Vegetative propagation

Dioscorea, Agave, Globba, Oxalis.

 

Sub-aerial stem modifications – Four types:

 

Type

Characters

Functions

Examples

Runners

Creeping plant with roots at each node

Vegetative propagation

Hydrocotyle, Oxalis

Stolons

Long, slender, obliquely down ward branches arises at the base of the stem

Vegetative propagation

Nerium, Jasminum, Rosa.

Suckers

Obliquely upward underground branches arises from axillary buds of under ground stem.

 Vegetative propagation

Chrysanthemum, Mentha

Offesets

In free floating hydrophytes, slender horizontally growing  one internode axillary branches

Vegetative propagation

Pistia , Eichornia

 

Underground stem modifications- Four types  ( multipurpose stem modifications)

 

Type

Character

Example

Rhizome

Horizontally growing underground stem ,dorsiventrally flattend  with adventitious roots

Zingiber, Curcuma, Musa

Corm

Vertically growing underground stem, with contractile  or pull roots.

Colacasia, Amorphophallus

Stem tuber

Root less underground stem, branch apices store food and become tuberous, eyes are indications of nodes . Each eye consists of scale leaf scar and axillary bud

Solanum tuberosum, Potato, Helianthus tuberosus.

Bulb

Dry disc like underground stem ,leaf bases store food

Tunicated-Allium cepa scaly bulb-Lilium candidum

 

Root

 

Root is the underground main axis of the plant body and it is developed from the radicle of the embryo.

 

Features of the Root system:

 

Root grows underground positively geotropic

Root is not differentiated into nodes and internodes

Leaves and buds are absent

Root is non chlorophyllous and brown in coloured

Lateral roots are formed endogenously in acropetal succession

Root apex is protected by root cap

Root hairs are unicellular .

 

Functions of Root system:

 

Roots provide anchorage to plants.

Roots absorb water and minerals from the soil

Roots conducts water and minerals to shoot .

 

Types of root system:

 

There are two types of root systems in Angiosperms.

They are 1. Tap root system   and  2. Fibrous root system.

Tap root system: Tap root develops from the radicle of the embryonal axis of germinating seed. It grows vertically into the soil and give rise lateral roots acropetally  eg. Dicotyledons like Arachis , Bean

Adventitious root system: Radicle is short lived and degenerate after some time and number of new roots develop from the base of the stem as fibres. This system of roots is called fibrou or adventitious root system.

 Eg. Monocotyledons Maize , paddy.

 

Modifications of root: When a permanent changes occurs in the structure of a root to perform new functions suitable for environment, it is called root modification. They are of following types;

 

Storage roots or Tuberous roots: In autotrophic plants some amount of food materials stored in roots and become tuberous. These roots are called storage roots or tuberous roots.

In biennials  tap roots modified into storage roots. Depending upon the shape of the tuberous roots  they are of three types.

  1. Spindle shaped  Eg. Rhaphanus sativus (Radish)
  2. Conical shaped  Eg. Daucus carota  ( carrot)
  3. Napiform (top shaped) Eg. Eg. Beta vulgaris (Beet root)

In some plants ,adventitious roots become tuberous. In Ipomea batatus dicot plant, single tuberous root at each node.Dahlia  and Ruellia  are dicot plants.

Fasciculated roots : fibrous roots become tuberous found in clusters at the base of the stem.Eg.Asparagus.

Normally food materials stored in the form of starch.Beta vulgaris store food in the form of sugars and Dahlia store in the form of inulin.

Roots store food materials are called root crops

Biennials store food materials in roots during first year by vegetative growth. In second year by utilizing the food materials stored in roots , they  flower ,fruits and seeds.So root crops harvested at the end of the first year.

 

Velamen roots or Epiphytic roots: In evergreen forests smaller plants donot get sufficient sunlight for their growth. These plants grow on the branches other big plants are called epiphytes. Epiphytes contain two types of roots namely  1. velamen roots   2. clinging roots.

Clinging roots are short ,branched and useful for fixing the epiphyte on branches of host trees.

Velamen roots: They are long ,thick, branched . They hang freely in the air. They have no root hairs. They contain special dead hygroscopic tissue useful to absorb moisture from the atmosphere.

Epiphytes have no contact with soil . They show xerophytic feature.

Eg. Vanda.

 

Photosynthetic roots Assimilatory roots: In some epiphytes roots become aerial , flattened and green coloured . They absorb moisture from the atmosphere and synthesise food by photosynthesis. Eg. Taeniophyllum, Tinospora, Trapa.

 

Respiratory roots or Pneumatophores: In some Mangroves growing in marshy places unable to get sufficient oxygen for growth .They produce  special aerial branches from the roots. These aerial roots possess minute pores called pnemathodes and roots bearing them are called pnematophores or respiratory roots. Eg. Rhizophora, Avicennia.

In Jussiaea, aerial roots become spongy and have porous. They act as breathing roots.

 

Nodular roots: Roots of legume plants show small nodules on roots . In nodules Rhizobium bacterium present . This bacteria fix atmospheric Nitrogen into Nitrates and supplies to plant . From legume plant bacteria get food and shelter.This type of mutual relation- ship is called symbiosis. Root nodule contain red pigment called leg-haemoglobin. Eg. Arachis, Dolichos.

 

Parasitic roots or Haustoria :Plants which depend on other plants completely or incompletely for their food  are called parasitic plants.

Host: The plant which provide food and shelter to parasite is called host.

Parasitic plants produce special nail like roots into vascular tissues of host to absorb food and water and minerals are called haustoria.Haustorial root penetrate into either root or shoot are called root parasites or stem parasites

Complete parasites are leafless, non-chlorophyllous and cannot synthesis their food material . They get nourishment from host vascular tissue by haustoria.

In complete parasites: They have leaves and synthesize food . For water and minerals  get from host by haustoria  from xylem .

 

 

                         Parasitic plants

 

Stem parasites                              Root parasites

 

Complete      Incomplete          Complete   Incomplete

 

Cuscuta        Viscum                Orobanche   Striga

Stem: The system which grows aerially in a plant is called Shoot system. It develops from the plumule  of the embryo. The common axis of the shoot system is called stem.

Stem bear the branches ,leaves, flowers ,fruits.

Features of the stem:

Stem is vertical growing axis.

Vertical growth of the stem is maintained by apical bud

Stem consists of nodes and internodes

Leaves develop on nodes . The upper angle between stem and leaf is called axil. In axils axillary buds develop which give rise either branches or flowers.

Young stems are green and woody stems are brown in colour.

Functions:

Stem helps to expose leaves to sunlight.

Stem helps in conduction

Modifications of Stem:

When a permanent changes occur in the structure of stems to perform new functions suitable for the environment, it is called stem modifications . .

Based on nature stem modifications are of three types they are

 

I. Aerial Stem Modifications   II. Sub-aerial Stem Modifications and

III. Underground stem modifications.

 

 Aerial Stem Modifications : The aerial stems, vegetative buds, floral buds, of plants growing in different environmental conditions undergo modifications and perform new functions , called aerial stem modifications.They are following types,

 

Tendril: Some weak stemmed plants produce long , wiry, coiled ,sensitive structures to climb over the support to get sunlight. Tendrils develop either from apical buds or axillary buds.

Ex. Passiflora- axillary bud modified into tendril

      Cissus –apical bud modified into tendril

Thorns: Hard, woody, pointed  vascular structures for protection are called thorns. They develop either from apical bud or axillary bud.

Ex. Bougainvillea- axillary bud for climbing

      Cissus – terminal bud modify into a pair of thorns for protection

Hooks: These are woody, curved and sensitive structures developed either from axillary bud or apical bud  for climbing .

Ex. Hugonia- auxillary buds of opposite leaves

Phylloclade: In desert plants to reduce transpiration leaves are modified into spines  or scale leaves, main stem or branches modified into green, flat leaf like structures to perform photosynthesis. These leaf like stems are called phylloclades

Ex. Opuntia, Casuarina, Cocoloba

Cladophylls or cladode : In the axils of sclale leaves , one or more shortend cylindrical or flat green branches develop to perform photosynthesis are called cladode.

Ex. Asparagus, Ruscus.

Tuberous stem: Aerial stems store food materials and become tuberous are called tuberous stems.

Ex. Brassical oleracea var.,gangyloides (knol-khol) , Bulbophyllum.

In Bulbophyllum, an epiphyte, one or more internodes of stem store food and become tuberous stems,they appear like pseudobulb.

Bulbil: In some plants vegetative buds or floral buds modified into condensed branches and store food materials, are called bulbils. They help in vegetative propagation.

Ex. Discorea bulbifera –bulbils develop in the axils of leaves.

 

Sub aerial stem modifications : In some weak stemmed plants  the stems remain partly aerial and partly underground. These stems are called sub-aerial stems.These are specialisedfor vegetative propagation. They are four types, 1. Runners,  2. Stolons,     3. Suckers,      4.  Offesets.

 

Runners: In some weak stemmed plants, the stems creep on the ground and produce adventitious roots at each node, when they detach from mother plant, they grow into individual plant. They help in vegetative propagation.

 Ex. Hydrocotyle vulgaris, Lippia nodiflora and Oxalis species

Stolons: In some plants the long , slender branches arise from the base of the stem grow obliquely and touch the soil and produce adventitious roots and become aerial. When they separate from mother plant , they liveas independent plants

 Ex. Nerium, Jasminum and Rosa.

Layering depends mainly on stolon principle.

Suckers:  The axillary buds of stem present below the soil, give rise branches which grow obliquely and become aerial . These branches at lower surface develop adventitious roots .These underground branches separate and become new individual plants.

 Ex. Chrysanthemum (chamanti ), Mentha (pudina) .

Offsets: Stems reduced to disc like structures and many leaves develop as rosette and below the stem bunch of roots develop . From the axils of leaves one internode branches develop and form bunch of roots below and and bunch of rosette leaves develop at apex. Instead of root caps , root packets are present . Mostly they are hydrophytes

 ex. Pistia, Eichornia.

 

Underground Stem Modifications : In some plants grow below the soil are called underground stems . 

These stems contain nodes, internodes, scale leaves, axillary and terminal buds.

Underground stems store food materials and become fleshy.

They help in vegetative propagation

They help in perennation

As they are underground , they are protected from herbivores. As they perform many functions underground stems are called multipurpose stem modifications.

Based on growth pattern, and the parts which stror food material, these stems are further divided into four types.

They are-

1.  Rhizome    2. Corm     3. Stem tuber    4. Bulb   

Rhizome: It is an underground stem, grows horizontally below the  under particular depth. It is dorsiventrally  flattend and produce aerial branches  from dorsal side, from ventral side adventitious roots are formed. It is with nodes and internodes . Scale leaves are present at nodes.Axillary buds present in scale leaves produce branches , they maintain horizontal growth of the rhizome.

 Ex. Zingiber officinalis (Zinger), Curcuma longa (turmeric)

Corm: It is underground stem, grows vertically below the soil under particular depth 

Leaf

Leaves are lateral appendages developed exogenously from the nodes of the stem . Leaves are green flat . They have limited growth. They arranged acropetally on the stem .

Types of leaves:

 Ramal: leaves develop on the branches are called ramal . eg. Hibiscus

Cauline: leaves develop directly on the stem . eg. Borassus, Cocos

Radicle: leaves look like they develop from the root . eg. Radish, Carrot.

Functions of Leaf: 1.photosynthesis 2. Transpiration  3. exchange of gases.

Parts of leaf : Leaf consists of four parts, l. leaf base, 2. stipules, 3. petiole, 4. Lamina

Leaf base: The basal part of the stem , useful to attach the stem.

Stipules: Small, green, lateral appendages present on either side of leaf base. They protect axillary buds during developmental stages.

In Ipomea qumoclit, the stipules are branched.

Petiole: The stalk of the lamina that connects lamina to the stem.

Lamina: Green expanded part of the leaf and it perform important functions of leaf.

Venation: The arrangement of veins in the lamina of the leaf .

Veins are vascular bundles of vascular tissue consists of xylem and phloem

Xylem useful to transport water and minerals

Phloem useful to transport food materials.

Main vein present in the centre of the lamina. Lateral veins arise from main vein or mid vein. From lateral veins , vein lets arise.

Uses: veins provide shape and  strength to leaf.

Veins help in transportation.

They help in to expose leaf to sunlight.

Types of venation: In Angiosperms venation is of two types,

1. Reticulate venation,   2. Parallel venation.

 

Reticulate Venation: Commonly found in dicots and rarely in some monocots like Smilax and Dioscorea.

Mid vein produces many lateral veins . Lateral veins divide and redivide and form net work  in the lamina . Depending on number of mid veins it is of two types , 1. pinnately reticulate and 2. palmately reticulate.

 

Pinnately Reticulate Venataion: Lamina contains a single mid vein  . It give rise lateral veins which give rise veinlets . Eg. Hibiscus, Mangifera.

 

Palmately or Multicostate Reticulate Venation: Lamina shows many mid veins which give rise lateral veins. It is of two types

  1. Convergent  2. Divergent

  

Convergent: Leaf is unlobed , mid veins unite at apex. Eg. Ziziphus.

Divergent: Leaf is lobes , mid veins run into lobes or towards margin. Eg. Passiflora,  gossypium ,Cucurbita.

Parallel venation: It is commonly found in Monocotyledons rarely in dicots like Caulophyllum and Erygium.

Veins run parallel to each other in the lamina. It is of two types,

1. pinnately parallel venation   2. palmately parallel venation

Pinnately Parallel Venation: Single mid vein which give rise lateral veins. Lateral veins are parallel to each other and run towards margin.

 Eg. Musa paradisiaca( banana)

Palmately Parallel Venation : Many prominent mid veins run parallel to each other. It is of two types,  1. convergent.  2. divergent.

Convergent: Mid veins run parallel to each other and united in unlobed leaf apex. Eg. Oryza.

Divergent: Mid veins  enter into each lobe separately in palmately lobed leaf lamina.  Eg.  Borassus.

Phyllotaxy: The mode of arrangement of leaves on lthe stem and branches is called phyllotaxy.Depending on number of leaves developed at each node, it is of three types,

1. Alternate/ Spiral Phyllotaxy: Only one leaf arise at each node. Leaves are arranged with definite gaps around the stem and found in definite vertical rows. Each row of leaves is called orthostichy. Eg. Hibiscus, Ficus.

Leaf Mosaic: It is a special pattern of alternate phyllotaxy. In this, the lower side older leaves have long petioles, and the upper younger leaves have shorter petioles. Upper younger leaves lie in the spaces present between the older leaves to get sufficient amount of sunlight.

Eg. Carica papaya and Acalypha indica.

2. Opposite Phyllotaxy: two leaves develop at each node lying opposite to each other. It is of two types

 Opposite superposed: The opposite leaves of all the nodes lie one above the other. Eg. Quisqualis.

Opposite decussate: The pair of leaves at one node lie at right angles to the next pair of leaves at the next node. Eg. Calotropis.

Whorled or circular Phyllotaxy: More than two leaves arise at a node, it is called whorled phyllotaxy. Eg. Nerium.

 

Leaf modifications: Entire leaf or part of leaf undergoes permanent change to perform new functions suitable for the environment, it is called leaf modifications. They are of following types,

1. Tendrils,            2. Spines,                       3. Scales leaves,

4. Phyllode,           5. Reproductive leaves, 6. Trap leaves.

Tendrils: In weak stemmed plants, entire leaf or part of leaf modified into long, wiry,slender, sensitive structure which useful to climb over the support are called leaf tendrils.

 

 

Part of leaf modified into tendril

Plant

Complete leaf

Terminal leaf lets of compound leaf

Leaf apex

Stipules

Petiole

Upper part of the petiole

Lathyrus wild pea

Pisum , garden pea

Gloriosa superba

Smilax

Clematis

Nepenthes

 

Spines: In some plants, leaves are modified into sharp, pointed structures  called spines. They useful to reduce transpiration in xerophytic plants and to protect plants from herbivore animals.

 

 

 

Part of leaf modified into spine 

 

Plants

Entire leaf

     Leaf apex

Stipules

     Leaf margin

First leaf of axillary bud

Asparagus, Opuntia

Agave, Yucca, Aloe

Acacia, Ziziphus,

Argemone

Citrus

 

 

Scale leaves: In some xerophytic plants and in undergroundstems, the leaves are reduced to small, colourless, dry membraneous structures called scales. In desert plants these are present on phylloclades to reduce the transpiration. In Underground stems they protect the axillary and apical buds.

Eg. Casuarina, Zingiber and Allium.

 

Phyllode: The petiole  or  secondary rachis is modified into green, flattended or winged structure performing photosynthesis, it is called a phyllode.

Eg. 1. In Acacia melanoxylon, the petiole is modified into  phyllode . In this plant  at seedling stage leaf is bipinnately compound. Later it falls off petiole become phylloed and perform photosynthesis.

     2. In parkinsonia, Stipules and primary rachis modifies into spines. While  secondary rachii modify into green ribbon like structure to perform photosynthesis. The small leaf lets present on phyllode , they soon falls off.

 

Reproductive Leaves: In some plants leaves produce buds  called epiphyllous buds and help in vegetative propagation.

Eg. In Bryophyllum, buds present in the notches of leaf margin,

In Scilla indica, the buds arise from the tip of leaf.

In Begonia , the buds arise ffrom the injured part of leaf.

 

Trap leaves: Plants growing in nitrogen deficient soils  depend on insects for their nitrogen requirements. In order to attract , catch and digest insects proteins their leaves are modified to trap leaves. Such plants are called Insectivorous plants. Trap leaves contain digestive glands , they secrete digestive juices contain proteolytic enzymes . They digest insect proteins and they are assimilated to plants.

Eg. Nepenthes, Drosera, Utricularia and Dionaea.

 

Nepenthes is called pitcher plant.

 In Nepenthes, Lower part of the petiole is modified into wing like structure

Upper part of the petiole is modified into Tendril,

Leaf lamina is modified into Pitcher,

Leaf tip is modified into  lid  

 

 The lid of the pitcher is colourful and immovable ,rim of pitcher is lined with nectary glands, and upper part of the pitcher has downward projecting hairs, the bottom of pitcher is filled with digestive juices , juices contain proteolytic enzymes

 

Insect is attracted by colourful lid, it sit on rim of pitcher and glides due to gland secretions and insect not able to come out due to downward projecting hairs and fell down in juices of digestive glands and digested due to proteolytic enzymes contained in it and nitrogen material of  insect is assimilated by the plant.

 

 

Flower: Flower is modified  and condensed stem for reproduction. Modified leaves are called floral leaves.

Thalamus or torus: the apical part of the pedicel is called thalamus.On this thalamus the nodes and internodes are condensed and at each node modified leaves ate present. These are called floral leaves. They are four sets namely, Calyx- whorl of sepals , outer most whorl , protective in function and green

Corolla- whorl of petals, second whorl, attractive and colourful

Androecium-whorl of stamens third whorl, male reproductive.

Gynoecium- whorl of carpels fourth whorl , female reproductive.

Essential organs: Stamens and Carpels. They are for reproduction.

Non-essential organs: Sepals and petals.They together called perianth.

 

Structure of flower:

Anterior side: The side present towards bract is called anterior side.

Posterior side: The side present towards main axis bearing the flower.

Bract: Flowers develop in the axils specialized leaves called bracts.

Bracteate: Flower with bract and represented as Br.

Ebracteate: Flower without bract represented as Ebr.

Pedicellate: Flowers with pedicel.

Sessile: Flowers without pedicel.

Bracteoles: They are small leaf like structures on pedicel

Bracteolate: Flowers with bracteole  and represented as Brl

Ebracteolate: Flowers without bracteole and represented Ebrl.

Bisexual: Flower with both stamens (androecium) and carpels (gynoecium).

Unisexual: Flower either with stamens or carpels.

Staminate flowers: Flower with only androecium.

Pistillate flowers: flower with only gynoecium.

 

Sex Distribution of plants: It is of three types,

Monoecious: Male and female flowers are borne on the same plant.

Eg. Cocos nucifera, Acalypha

Dioecious: Male and female flowers borne on the separate plants.

Eg. Borassus and Vallisneria

Poygamous:  unisexual and bisexual flowers are borne on the same plant

Eg. Mangifera, Polygonum

Symmetry of flower: Based on arrangement, number and structure of floral parts, the symmetry of flower is of different types.

 

Based on arrangement symmetry of flower:-

Acyclic:-Floral leaves arranged spirally on the thalamus eg. Magnolia.

Hemicyclic:- Perianth lobes arranged in whorls but stamens and carpels in spirals. Eg. Annona, Polyalthia

Cyclic:- Floral parts arranged in circles eg. Hibiscus and Datura.

Merosity:Number of floral parts in each whorl of a flower refers to it merosity. Accordingly,it is following types.

Trimerous: In each whorl floral parts are three or its multiples eg. Allium

Tetramerous: In each whorl floral parts are four or its multiples eg.Brassica

Pentamerous: In each whorl floral parts are five or its multiples eg.Hibiscus

Trimerous flowers found in Monocots.

Tetramerous and pentamerous flowers found in dicots plants.

 

Structural symmetry: They are of three types,

Actinomorphic: Flower can cut into two equal halves by any vertical section, passing to the centre. Eg. Hibiscus.

Zygomorphic: Flower can divided into two similar halves through on direction only.Eg. Dolichos, Ocimum.

Asymmetric flower: This flower cannot be cut into two equal halves in any plane. Eg. Canna indica.

 

Position of gynoecium on the thalamus:

 Based on position of gynoecium  on the thalamus in relation to floral leaves, flowers of three types,

Hypogynous: Thalamus is convex or flat. The gynoecium is arranged on the thalamus. The remaining floral leaves calyx, corolla, androecium are arranged at the base of the gynoecium. Ovary is superior.Eg. Hibiscus.

Perigynous: Thalamus is concave or saucer shaped with a centrally located gynoecium. The remaining floral parts like calyx, corolla, androecium are arranged along the margin of thalamus. Wall of the ovary not unite with thalamus. Ovary is  half inferior.  Eg.Tephrosia.

Epigynous: Thalamus is deep cup like structure , inside which the gynoecium is arranged. The walls of the ovary and thalamus fused.The remaining floral leaves like calyx, corolla, androecium arranged along the margin of thalamus , that is above the ovary. Ovary is inferior. Eg. Tridax.  

 

Perianth: Calyx and corolla together called perianth.

Achlamydeous flower: Perianth is absent. Such flowers are called naked flowers. Eg. Male and female flowers of Cyathium.

Chlamydeous flowers: Flowers with perianth . They are of two types,

a. Monochlamydeous: Perianth arranged in one whorl. Eg. Croton,

b. Dichlamydeous: Perianth is in two whorls. It is of two types,

i. Homochlamydeous: Perianth in two whorls and with no differentiation. Eg. Allium cepa.

ii. Heterochlamydeous: Perianth is in two whorls and they are differentiated into calyx and corolla. Eg. Hibiscus.

 

Aestivation: The mode of arrangement of perianth lobes in bud condition.

It is of following types;

Valvate: Perianth lobes are arranged closely with small gaps between them. They are free or united. Eg. Calyx of Hibiscus.

Twisted: Perianth lobes overlap one aother .All perianth lobes , one margin is inside and the other one is outside. Eg. Corolla of Hibiscus.

Ascendingly Imbricate: Each perianth lobe overlaps the perianth lobes present posterior to it. Overlapping is anterior to posterior. Eg. Corolla of Caesalpinaceae.

Descendingly Imbricate: Each perianth lobe overlaps the perianth lobe preset anterior to it. So Overlapping is posterior to anterior. Eg. Corolla of Fabaceae.

Quincuncial: Overlapping perianth lobes is two completely outside and two completely inside and  one perianth lobe one margin is inside and other margin is out side. Eg. Calyx of Catharanthus.

 

Calyx: First and outer most whorl the flower and made up of sepals.

Sepals are green structures and protect the inner whorls of floral leaves in bud condition.

Polysepalous: sepals are free. Gampsepalous: sepals are united.

Ephemeral sepals: sepas fall off befor or after fertilization.

Persistent Calyx: Sepals remain attached to fruit. They are of two types

Marscescent calyx: persistent calyx not grow with fruit.

 Eg. Solanum,Capscium

Acrescent calyx: persistent calyx grow along with fruit and covers it.

 Eg. Physalis  

 

Corolla: Second whorl of floral leaves and consists of petals. They are colourful and attractive.

Polysepalous: petals are free.  Gampetalous: petals are united.

 

Androecium: Third whorl  made up of stamens. Male reproductive parts.

They also called microsporophylls. They produce pollen grais.

Staminodes: sterile stamens eg. Cassia.

Parts of stamens: Each stamen has two parts. 1. anther  2. filament.

Anther bear one or two sacs called anther lobes, produce pollen grains.

Dithecous anther: Two lobed anther . Eg. Datura.

Monothecous anther: One lobed anther . eg. Hibiscus.

Extrorse: Dehiscence of anther towards outside of the flower. Eg. Hibiscus.

Introrse: Dehiscence of anther is towards inside of flower. Eg. Datura.

 

Attachment of filament to anthers : It is of following types,

Basifixed: Filament attach to the base of filament. Eg. Datura.

Adnate: Filament attach to  the whole length at the back of anther. Eg. Nelumbo

Dorsifixed: Filament is attached at the middle of dorsal side of anther .Eg. Hibiscus.

Versitile: The apex of filament is pointed and attached at the back of anther. So that anther swing freely in any direction. Eg. Oryza.

Length of stamens:

Didynamous: Androecium has four stamens in which two are long and two are short. Eg. Ocimum.

Tetrdynamous: Androecium has six staments in which outer two stamens shorter and inner four stamens are long. Eg. Brassica.

 

Based on length of stamens compared to other floral parts.

Inserted stamens: Filaments are shorter than the petals. Eg. Datura.

Exerted stamens: Filaments are longer than the petals . eg.  Acacia Arabica

 

Union of stamens: It is of two types , 1. Cohesion. 2. Adhesion.

Cohesion: Fusion among the stamens of flower. Union of stamens among filaments or anthers or both.It is of three types,

1.Adelphy: Filaments united and anthers free. Stamens arranged in bundles.

It is of three types.

  1. Monoadelphous : filaments of stamens uninted into one bundle. Eg. Hibiscus
  2. Diadelphous: filaments united into two bundles . Nine filaments in one bundle and tenth one free. Eg. Dolichos.
  3. Polydelphous: Filaments united into many bundles. Eg. Citrus.

2.Syngenesious: Anthers of all stamens united and filaments are free. Eg. Disc florets of Tridax and Helianthus. Asteraceae family.

3. Synandry: Both filaments and anthers of stamens united. Eg. Cucurbita.

Adhesion of stamens: Fusion of stamens with other whorls of flower like calyx, corolla, and gynoecium. It is of four types.

  1. Episepalous: stamens attached to sepals. Eg. Grevillea.
  2. Epipetalous: stamens attached to petals. Eg. Datura.
  3. Epiphyllous: stamens attached to perianth or tepals Eg. Asparagus.
  4. Gynostegium: stamens attached to stigma . Eg. Calotropis.

 

Dehiscence of anthers: At maturity anthers dehisce and liberate pollengrains. It is of following types.

Longitudinal dehiscence: Anthers dehisce longitudinally. Eg. Datura.

Transverse dehiscence; Anthers dehisce transversly. Eg. Hibiscus.

Valvular dehiscence: Anthers dehisce like a valve. Eg. Cassytha.

Porous Dehiscence: At maturity pores are formed at the apex of anthers and release pollen grains eg. Solanum.

 

Gynoecium or Pistil : It is fourth or innermost whorl of the flower. It is made up of carpels. They are female reproductive parts.  Carpels also called megasporophylls.

 

Typical carpel parts: It consists of three parts,

1. Ovary, 2. Style, 3. Stigma.

Ovary is swollen , sac like structure  with ovules

Style is elongated structure

Stigma is apical portion of style, useful to receive pollen grains.

 

Number of carpels, Gynoecium is following types

Monocarpellary gynoecium madeup of one carpes eg. Dolichos.

Bicarpellary gynoecium madeup of two carpels eg Solanum

Tricarpellary gynoecium madeup of three carpels eg Allium

Tetracarpellary gynoecium madeup of four carpels eg Solanum

Pentacarpellary gynoecium madeup of five carpels eg Hibiscus

Multicarpellary gynoecium madeup of many carpels eg Abutilon.

 

Fusion of carpels: Carpels fused or free.

Apocarpous: carpels on the thalamus remain free. Each carpel has ovary style and stigma. Eg. Nelumbo, Michelia.

Syncarpous: Carpels of gynoecium fused completely ( Datura) or partially (Hibiscus).

Ovary:Ovary is basal portion of gynoecium. It encloses ovules. After fertilization ovary will become fruit and ovules into seeds.

In syncarpous gynoecium, the margins of carpels fold inside and unite in the centre. Due to this cross walls formed between carpels.These walls are called septa. Septa divide ovary into locules.

Number of locules in the ovary:

 

Type of ovary

Number of locules

Examples

Unilocular

One locule

Dolichos

Bilocular

Two locules

Solanum

Trilocular

Three locules

Allium

Tetra locular

Four locules

Ipomea

Pentalocular

Five locules

Hibiscus

Multilocular

Many locules

Abutilon

 

Placentation: Ovary is made up of one or more carpels . The union place of carpels is called placenta to which ovules are attached. The mode of arrangement of ovules on placenta is called placentation. It is of following types.

 

Marginal Placentation: The ovary is unilocular. Ovules are borne on ventral suture of ovary. Eg. Dolichos.

Parietal placentation: The ovules are borne on the inner walls of the ovary or on intrusions  or on false septa of the ovary. Eg. Brassica , Cucurbita.

Axile placentation: The ovules are attached to the central axis of bilocular to multilocular ovary.Eg. Hibiscus.

Free central Placentation: This placentation is developed from axile placentation with degeneration of septa. So multilocular ovary becomes unilocular. And the ovules develop all around the centra axis. Eg.Dianthus.

Basal Placentation: In unilocular ovary, one or more ovules develop at the base of the ovary. Eg. Tridax, Helianthus.

Superficial placentation: In multilocular ovary , ovules develop all round the inner surface of the septa. Eg. Nymphea.

 

Style: Elongated part of the gynoecium  betweeb ovary and stigma. Depending on position it is of three types,

  1. Terminal style: Style arise at apical part of ovary.  Eg. Datura
  2. Lateral style: Style arise lateral side of ovary  eg. Mangifera.
  3. Gynobasic Style:Style arise from the base of the ovary in between the four locules. eg. Ocimum

 

Stigma: Terminal part of the style which receives pollen grains .Pollen grains germinate on the stigma with the help of sugar like substances secreted by it.

Inflorescence:The mode of arrangement of flowers on the peduncle is called inflorescence.

The peduncle is modified stem on which flowers arranged.

Flowers are attached to peduncle with stalks called pedicels.

Flowers with pedicels are called pedicellate.

Flowers without pedicels are called sessile.

 

Types of inflorescences : Based on position , they are of three types,

Terminal inflorescence: These infloresceces are developed from the apices of main stem or branches eg. Crotalaria and Croton.

Axillary inflorescences: These are developed from axils of leaves. Eg. Dolichos.

Intercalary inflorescences: This type of inflorescence is borne at the internodes. The stem continues its growth after the formation of inflorescence. Eg. Callistemon.

Cauliflory: In some plants the flowers are formed directly on older stem.

Eg. Polyalthia, Theobroma.

 

Types of Inflorescences

Inflorescences are of three types depending upon the growth and development of peduncle. They are 1. Racemose 2. Cymose, 3. Special types

Racemose or Indefinite Inflorescences:

Features: 1.Peduncle grows indefinitely

2.Flowers develop on peduncle in acropetal manner i.e. mature flowers towards the and younger ones toward apex of peduncle.

3.If peduncle is condensed flowers arranged in centripetally i.e. mature flowers towards periphery and young flowers in the centre.

4.Peduncle is unbranches (simple),   branched (compound)

 

Racemose inflorescence with pedicellate flowers: They are of following types

Simple Raceme: Peduncle is simple, unbranched, elongated, producing many pedicellate , bracteates flowers in acropetal manner. Eg. Crotalaria.

 

Compound Raceme: Also called Panicle. Peduncle is branched and each branch produces pedicellate, bracteates flowers acropetally. Each branch resembles a simple raceme. Eg. Mangifera indica and Yucca.

 

 

 

Simple Corymb: Peduncle grows indefinitely and produce many pedicellate bracteate flowers in acropetal manner. The lower flowers have longer pedicels and apical flowers have shorter pedicels. So all the flowers are brought more or less  to the same height. Eg. Gynandropsis and Cassia.

 

Compound Corymb: Peduncle is branched and each branch is produced into a simple corymb.

 Eg. Brassica oleeracea var. botrys (cauliflower). Pyrus malus

 

Simple Umbel : Peduncle is unbranched and condensed. Many pedicellate and bracteates flowers arise from its apex in a  cluster. All the flowers open in a centripetal manner. At the base of flowers, all the bracts form a whorl called Involucre . Eg. Allium cepa. (onion).

 

Compound Umbel: Peduncle is branched and each branch produces a simple umbel at its apex. All the braches arise in umbel like manner. The involucre of bracts is present at the base of the branches. At the base of simple umbels, a number of bracts  are present and form a whorl called involucel of bracts

Eg. Coriandrum sativum and Daucus carota.

 

Racemose inflorescences with sessile flowers: They are of following types.

Simple spike: The peduncle is unbranched  and produces bracteates, sessile flowers acropetally. It is identical with simple raceme, but the flowers are sessile.

 Eg. Achyranthus, and Amaranthus.

 

Compound Spike: The peduncle is branched and grows indefinitely.

The branches produce bracteates, sessile flowers acropetally. These branches are called spikelets.

The axis of each spikelet is called rachilla.

 The bracts developed on the rachilla are called glumes.

The basal glumes do not produce flowers, they are called sterile glumes.

The middle glumes glumes are fertile and produce sessile flowers in their axils and are called lemma

The reduced bracteoles of the flowers are called palea.

The perianth lobes are reduced and are called lodicules.

The stamens and gynoecium  develop above the lodicules.

It is the characteristic inflorescence of the family Poaceae

 Eg. Triticum and Oryza. 

Catkin: It is a spike like inflorescence, but the peduncle is long, weak and drooping. On this peduncle many sessile, unisexual flowers develop acropetally. It is often called Amentum

Eg. Casuarina and Acalypha.

 

Simple Spadix: Peduncle is fleshy, unbranched and produces many sessile, bracteates, unisexual flowers acopetally.

 Female flowers are at the base and male flowers at the apex. In between male and female flowers, there are neuter flowers.

 The terminal part of the peduncle is flowerless and it is called appendix. One of the bracts is modified  into a thick leathery structure  called spathe. It covers the entire inflorescence. This inflorescence is common   in the members of Aroideaae family.   Eg. Colocasia.

 

Compound Spadix: Peduncle is branched and  on the branches many sessile, unisexual flowers develop acropetally. Female fowers are developed at the base and male flowers at the apex. Entire inflorescence is covered by a hard. Woody, boat like spathe. Eg. Cocos.

 

Head or Capitulum or Anthodium: Highly evolved inflorescence.

Feature of Asteraceae family.

Peduncle is condensed into flattend disc like structure called receptacle.

Many sessile flowers called florets closely arranged on receptacle in centripetal manner

Inflorescence is protected by involucre  of bracts.

Inflorescence is with two types of florets namely disc florets and ray florets.

Based on type of florets, head inflorescences are of two types,

 

Homogamous head: In this type of inflorescence only one type of florets are present. In Vernonia only disc florets are present. In Tagetus, only ray florets are present.

 

Heterogamous Head: In this both ray and disc florets are present.The ray florets arranged towards periphery, and disc florets  in the centre of receptacle. Eg. Helianthus and Tridax.

 

Compound Head: Axia of head is branched  and each branch is a head.

 Eg. Echinops, Spheranthus.

 

 

Cymose or Indefinite Inflorescences: Features:

1.Growth of the pdduncle is stopped due to the developmet of a flower  at its apex.

2. The bracts on the axis below the  this flower produce branches which also terminates with single flower.

3. Flowers are produced either in basipetal arrangement or in centrifugal arrangement.

4. Basipetal arrangement means older flowers at the top  and younger ones at the bottom.

5. Centripetal arrangement, the older flowers are present at the centre and younger ones near the periphery of the condensed peduncle

 Types of cymose inflorescences:

Solitary Cyme: Simplest cymose type.

The inflorescence axis is unbranched and bears single flower at its apex

In Hibiscus , the solitary flower is axillary. In Datura, the solitary flower is terminal.

Simple Cyme or Cymule: Inflorescence axis terminates with single flower. Below this flower the main axis produces two lateral branches which also end in a flower. Thus a three flowered inflorescence is formed. The flowers are arranged in basipetal manner. Eg. Jasmium  and Bougainvillea.

 

Monochasial cyme: It is a cymose inflorescence in which the inflorescence axis terminates into a flower and produces only one branch from its basal bract. This branch also grows definitely and ends with a flower. In this way many single branches develop to form an axis .This axis is called sympodial axis. Though it looks like racemose, the flowers are not borne in the axil of bracts but are arranged opposite to bracts.

 

Depending on the arrangement of branches it is of two types,

 

  1. Helicoid cyme: Successive lateral branches develop on one side only

Eg. Hamelia

  1. Scorpioid cyme : lateral branches develop successively on either side in zig-zag manner. Eg. Heliotropium and Solanum

 

Dichasial Cyme: Axis of inflorescence terminates with flower, and produces two lateral branches below it . Each branch also terminates with single flower.These two branches repeat same type of growth. Two branches develop at each time. Eg. Cleodendron and Ipomoea.

 

Polychasial Cyme: Axis of inflorescence terminates with flower, and produces many lateral branches below it. Each branch also terminates with single flower. These branches repeat same type of growth. Many branches develop at each time. Eg. Nerium.

 

Special types of Inflorescences:

 

Verticillater: Feature of Lamiaceae.

Flowers arise in the axils of opposite leaves at every node.

Flowers develop initially in dichasial cyme and  later end as monochasial scorpioid cyme.

The flowers are sessile, and crowded around node as false whorl called verticel. Hence it is called verticellaster. Eg. Leucas and Leonotis.

 

 

Dichasial cyme +Monochasial scorpioid cyme=Verticellaster.

 

Cyathium: Single flower like special inflorescence found in Euphorbiaceae.

Involucre of bracts is cup like.

In the centre of cup single female flower with long stalked tricarpellary,syncarpous pistil.

Around female flower, many male flowers arranged in scorpioid cyme.

Each male flower is single stalked stamen.

Flowers are achlamydeous.

Flowers arranged in centrifugal manner.

Eg. Poinsettia and Euphorbia.

 

Hypanthodium: It is fruit like inflorescence.

Inflorescence axis is condensed and forms a fleshy cup like structure with an apical opening.

Small, sessile,unisexual develop inner wall of of the cup.

Male flowers near apical opening, female flowers at the base  and in between male and female flowers sterile flowers ( gall flowers ) are present.

Opening of flowers not in definite order.  Eg. Ficus sps.

 

Pollination : The process of transfer of pollen grains from the anther to stigma .

Pollination is of two types, Indirect pollination, in angiosperms ovules are inside ovary and pollen grains fall on stigma and then reach ovules through style and  ovary.

Direct pollination , pollen grains directly fall on ovary in gymnosperms.

Types of pollination in Angiosperms: It is of two types, 1. self pollination and 2. cross pollination.

Self pollination : The transfer of pollengrains from the anthers to the stigma of the same flower is called self pollination or autogamy.It is found in cleistogamous and chasmogamous flowers. 

Cross pollination:The transfer of pollen grains from the anthers of one flower to the stigma of another flower of the same species  is called cross pollination or allogamy. It is of two types

Geitonogamy:  Transfer of pollengrain from two flowers of the same plant.

Xenogamy: Transfer of pollen grains from the one flower to another flower stigma of different plant of same species.

Cross pollination is advantageous than the self pollination. Hence though  many flowers are bisexual , they undergo cross pollination by controlling self pollination.

Contrivances of cross pollination:

Dicliny or Unisexuality: In some plants flowers with either  androecium or gynoecium. Such flowers are called unisexual flowers. Production of such flowers is called unisexuality or dicliny.Male flowers are called staminate flowers and female flowers are called pistillate flowers.  In such plants cross pollination occurs. Eg. Vallisneria.

Dichogamy: It is one of the mechanism which prevent self pollination in bisexual flowers. In this bisexual flowers  androecium and gynoecium mature are at different times. It is of two types.

Protandry: In a bisexual flower androecium mature earlier than gynoecium . It is called protandry. Eg. Helianthus, Cleodendron and Gossypium.

Protogyny: In a bisexual flower gynoecium mature eallier than androecium and is called protogyny. Eg. Solanum , Scrophularia.

Herkogamy: The arrangement of male and female reproductive organs at different levels in a bisexual flower is called herkogamy. Flowers bisexual and androecium and gynoecium  mature  at time, self pollination is prevented as they are in different heights or in different directions.

 In Hibiscus stamens and stigmas are in different heights.

 In Gloriosa stamens and stigmas in different directions.

Heterostyly: The presence of styles in different lengths in the flowers of the same species. It is of two types 1. Diherostyly and 2. Triheterostyly.

Diheterostyly: In some plants two forms of flowers  are present. Such flowers are called dimorphic flowers.Arrangement of styles in two different heights in dimorphic flowers is called diheterostyly. In first type of flowers the style is short and the stamens are long . In second type of flowers the style is long and the stamens are short. In these dimorphic flowers , cross pollination takes place between the flowers having syles and stamens of the same height. These dimorphic flowers also exhibit dichogamy.Eg. Primula, Oledenlandia.

Triheterostyly: In some plants three forms of flowers are present. Such flowers are called trimorphic flowers . In these flowers the styles and stamens are arranged in three different lengths ( short, long and medium ) . such type of condition I which three heights of styles present is called triheterostyly. Eg. Lythrum  and some species of Oxalis.

Self sterility: In some bisexual flowers , if the pollen grains fall on the stigma of the same flower, germination does not occur. This is called self sterility. Eg. Abutilon and passiflora

Pollen prepotency: When the stigma receives pollen grains from the same flower as well as from another flower of the same species at a time, the foreign pollengrain germinate earlier than the same flower pollen grain. Eg. Dolichos.

Sensitive stigmas: In some flowers stigma and stigmatic lobes sensitive to touch. Stigma lobes closed when the same flowers anthers dehiscence. Later receptive surface will become open. Hence cross pollination takes place. Eg. Martynia.

 

Self Pollination: In Yucca, cross pollination occurs by a moth called Pronuba yuccasella. With out this moth cross pollination not occur. In such condition flowers depend on self pollination. 

Contrivances of self pollination:

Homogamy: In plants with bisexual flowers ovary and stamens mature at same time self pollination occurs. Eg. Caltha, Ranunculus.

Movement of floral leaves: Due to wind currents , the pollen grains may fall on the stigma of the same flower and self pollination takes place. During sleeping movements also anthers touch the stigma and transfer the pollen. Eg. Argemone.

Safety Mechanism: In cross pollinated flowers self pollination occurs if cross pollination fails to occur. It is called safety mechanism. In the members of Asteraceae, disc florets ,protandrous. In these flowers cross pollination fails, stigmatic lobes bend and receive pollen grains on the stamens for self pollination.

Cleistogamy: Flowers which do not open are called cleistogamous flowers. Pollen grains fall on the same flower. Eg. Commelina benghalensis, Streptocarpus princeps

Agents for cross pollination:

Pollen grains reach stigma with the help of agents . The pollination mechanism is the relationship between agent and flower structure.

 

 

 

Agents of cross pollination

 

Technical terms for type of pollination

 

Examples

Abiotic                wind

 

                            water

 

Biotic

Animals               Birds

                             Bats

                            Insects

                            Snails

Anemophily

Epihydrophily

 

Hypohydrophily

 

Orinithophily

Chiropterophily

Entomophily

Malacophily

Oryzae

Vallisneria

 

Zostera

 

Bignonia

Kigelia pinnata.

Cestrum noctrunum

Aroids                        

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Describe the cell structure of Spirogyra.

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Describe the scalariform conjugation in Spirogyra

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Describe direct lateral conjugation in Spirogyra.

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Write the differences between scalariform cougation and lateral conjugation in Spirogyra.

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Describe types of hyphae in Rhizopus.

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Describe the asexual reproduction by sporangiospore sporangia in Rhizopus

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Describe sexual reproduction in in Rhizopus

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Describe sexuality in Rhizopus

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Explain male and female shoot in Funaria.

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Describe capsule of Funaria with labelled diagram

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Describe protonema of Funaria.

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Describe asexual reproduction in Pteris.

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Describe sexual reproduction in pteris.

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Describe prothallus in pteris.

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 Describe anatomy of Pteris rhizome.

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Describe anatomy of cycas leaflet with labelled diagram

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Describe L.S. of Cycas ovule.

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Describe external features of cycas.

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Explain internal anatomy of corolloid roots.

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Describe corolloid roots.

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Describe male cone , microsporangium

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Describe microsporophyll and megasporophyll.

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Explain the structure of bacteria cell

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Describe conjugation in Bacteria.

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Bacteria are friends and foes to humans Explain.

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Describe the structure of bacteriophage and Tobacco Mosaic Virus.

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Explain replication in viruses.

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Mention the differences between lytic cylce and lysogenic cycle.

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Explain common reactions that occur in both aerobic and anaerobic respiration.

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Describe Krebs cycle or TCA cycle or Citric acid cycle.

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Describe components in Electron Transport System.

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Describe electron transport and protan translocation in ETS.

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What is R.Q. Explain different substrates R.Q.values.

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Explain fermentation.

 

 

Botany.doc (43 kB)

 

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