Flowers are the reproductive parts of plants,which are responsible for the production of gametes or sex cells ((non flowering plants).
A flower is modified shoot in which the leaves are modified into floral parts. A blossom propagates a branch from a bud in the axil of a little leaf-like structure called the bract. A bract is commonly green due to presence of chlorophyll and is a very small structure (non flowering plants).
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs.
In addition to facilitating the reproduction of flowering plants, flowers have long been admired and used by humans to bring beauty to their environment, and also as objects of romance, ritual, religion, medicine and as a source of food.
In this lesson you will learn about :
1) Flower - Definition & Functions
2) Floral Symmetry
3) Pedicellate & Sessile Flowers
4) Insertion of Floral Leaves on the Thalamus
5) Parts of a Flower
6) Some Important Terms related to Flowers
7) Floral Whorls - Calyx, Corolla, Androecium and Gynoecium
8) Placentation
9) Inflorescenece
I hope this document is helpful to you. Please share the document with your friends if you think this will benefit them. Get ready for the next lesson. Thanks.
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs.
In addition to facilitating the reproduction of flowering plants, flowers have long been admired and used by humans to bring beauty to their environment, and also as objects of romance, ritual, religion, medicine and as a source of food.
In this lesson you will learn about :
1) Flower - Definition & Functions
2) Floral Symmetry
3) Pedicellate & Sessile Flowers
4) Insertion of Floral Leaves on the Thalamus
5) Parts of a Flower
6) Some Important Terms related to Flowers
7) Floral Whorls - Calyx, Corolla, Androecium and Gynoecium
8) Placentation
9) Inflorescenece
I hope this document is helpful to you. Please share the document with your friends if you think this will benefit them. Get ready for the next lesson. Thanks.
angiosperms
morphology of a flowering plant
parts of flowering plant.
What are angiosperms? Angiosperms are plants that produce flowers and bear their seeds in fruits. They are the largest and most diverse group within the kingdom Plantae, with about 300,000 species. Angiosperms represent approximately 80 percent of all known living green plant.
The outstanding and most significant feature of the flowering plants (and that which sets them out from other vascular plants) is the flower. Understanding the flower structure and names of the parts is important as it is the most important set of characters for both recognizing and keying species, genera, families, etc.
Floral parts (terms & illustrations)
1. Peduncle / pedicel - floral stalk
2. Receptacle - the modified shoot or floral axis
3. Sepals / calyx - the outer most whorl; collectively all sepals are called the calyx. Sepals are typically green and protect the inner floral parts in buds
4. Petals / corolla -the next whorl, collectively all petals are called the corolla. Petals are typically brightly colored and and assist in attracting pollinators. The sepals and petal combined are called the perianth. If the perianth parts cannot be differentiated into sepals and petals, that is, that look so much alike, then they are called tepals.
5. Stamens (androecium) - the next whorls, each stamen has two parts: filament and anthers. Androecium or "male house", the name for all the stamens. The anthers house the microsporangia which undergo meiosis and produce pollen grains.
6. Nectaries - are often associated with flowers, they are found at the receptacle and offer a reward to animal pollinators.
7. Carpels (gynoecium) - The innermost and final whorl is composed of all the carpels and is the site for pollination and fertilization. Collectively all carpels are called the gynoecium: "female house". Carpel has three parts: stigma which receives pollen, the style which is the a slender region specialized for pollen tube growth and the ovary which is an enlarged basal portion and surrounds and protects the ovules. The structure(s) in the center of the flower are often referred to as the pistil(s). Pistil is a layman's term for "flask-shape" structure, so anything with that structure is called a pistil. This is one of the more confusing parts of the flower; more on this below.
lab 1: introduction to flowers + clove, for second year pharmacy students, Al-Azhar University by Dr Mahmoud Sallam demonstrator at pharmacognosy department.
The stem bears leaves, buds, flowers & fruits & helps to spread them out so that they can function properly. For example, it helps to spread out the leaves in such a way that they get the maximum possible sunlight and air..
It is a type of cyclic flow of nutrients between non- living components like soil, rock air and water and living organisms and micro oganism (Pseudomonas and Aeruginosa). It makes the biosphere dynamic. In oxygen cycle there is a cyclic flow of atmospheric oxygen. Photosynthesis releases oxygen in the atmosphere. Respiration absorbs oxygen. By photosynthesis plant produces organic molecules (C6 H12 O6). By respiration that organic molecule is oxidized to release energy and carbon oxide.
angiosperms
morphology of a flowering plant
parts of flowering plant.
What are angiosperms? Angiosperms are plants that produce flowers and bear their seeds in fruits. They are the largest and most diverse group within the kingdom Plantae, with about 300,000 species. Angiosperms represent approximately 80 percent of all known living green plant.
The outstanding and most significant feature of the flowering plants (and that which sets them out from other vascular plants) is the flower. Understanding the flower structure and names of the parts is important as it is the most important set of characters for both recognizing and keying species, genera, families, etc.
Floral parts (terms & illustrations)
1. Peduncle / pedicel - floral stalk
2. Receptacle - the modified shoot or floral axis
3. Sepals / calyx - the outer most whorl; collectively all sepals are called the calyx. Sepals are typically green and protect the inner floral parts in buds
4. Petals / corolla -the next whorl, collectively all petals are called the corolla. Petals are typically brightly colored and and assist in attracting pollinators. The sepals and petal combined are called the perianth. If the perianth parts cannot be differentiated into sepals and petals, that is, that look so much alike, then they are called tepals.
5. Stamens (androecium) - the next whorls, each stamen has two parts: filament and anthers. Androecium or "male house", the name for all the stamens. The anthers house the microsporangia which undergo meiosis and produce pollen grains.
6. Nectaries - are often associated with flowers, they are found at the receptacle and offer a reward to animal pollinators.
7. Carpels (gynoecium) - The innermost and final whorl is composed of all the carpels and is the site for pollination and fertilization. Collectively all carpels are called the gynoecium: "female house". Carpel has three parts: stigma which receives pollen, the style which is the a slender region specialized for pollen tube growth and the ovary which is an enlarged basal portion and surrounds and protects the ovules. The structure(s) in the center of the flower are often referred to as the pistil(s). Pistil is a layman's term for "flask-shape" structure, so anything with that structure is called a pistil. This is one of the more confusing parts of the flower; more on this below.
lab 1: introduction to flowers + clove, for second year pharmacy students, Al-Azhar University by Dr Mahmoud Sallam demonstrator at pharmacognosy department.
The stem bears leaves, buds, flowers & fruits & helps to spread them out so that they can function properly. For example, it helps to spread out the leaves in such a way that they get the maximum possible sunlight and air..
It is a type of cyclic flow of nutrients between non- living components like soil, rock air and water and living organisms and micro oganism (Pseudomonas and Aeruginosa). It makes the biosphere dynamic. In oxygen cycle there is a cyclic flow of atmospheric oxygen. Photosynthesis releases oxygen in the atmosphere. Respiration absorbs oxygen. By photosynthesis plant produces organic molecules (C6 H12 O6). By respiration that organic molecule is oxidized to release energy and carbon oxide.
Intestine part of the alimentary canal is prone to many infections which we term as nutritional diseases which may lead to its inflammation. The various infectious agents causing nutritional disorders are bacteria, virus, tapeworms, roundworms, threadworms, hookworm, pin worm etc. Here are some common nutritional diseases or disorders of the digestive system (marasmus)
INTRODUCTION OF ALTERNATIVE SOURCES OF ENERGY: We know that by the time conventional sources of energy will deplete soon due to improved technological progress and increased demand. To cater the rising demand, keeping a balance with limited with limited availability of conventional sources is very important. It is mandatory to look up to the alternative sources of energy which we also term as non-conventional sources of energy.
We perform many activities consciously or unconsciously, for example, when we eat food, our eyes help to locate the food, the nose smells it, hands bring food to the mouth, teeth chew and masticate it, the tongue pushes the food inside the alimentary canal, and so on. (NERVOUS SYSTEM FUNCTION) All these activities occur in a coordinate manner. The organ system in our body that brings about coordination and integration of body activities, is the nervous system.
LIKE BEGETS LIKE, which means young one resemble their parents, (MONOHYBRID CROSS & DIHYBRID CROSS) is the well-known dogma associated with heredity. Each species has similarities among themselves due to the cause of heredity. W.Bateson was the first one to coin the term genetics in 1905. It is derived from the greek word “genesis” means to grow into or to become . in other word, genetics is the study of heredity and variation.
Events of fertilization
A] Pollination brings female and male gametophyte together- The male and female gametophytes must meet and unite their gametes to fertilize egg. This is done by pollination, in which pollen is placed on the stigma of the carpel.
B] Germination of pollen grain under suitable condition- The cytoplasm of the pollen grain absorbs sugar and water from the stigma and bulges out to produce a tube known as pollen tube by braking down exine of pollen grains. This germinating pollen tube grows down through the stigma and style of flower towards the micropyle of the ovary. This tube produces chemical, calcium such as that dissolves the tissues of the style and the tip of the pollen tube enters the ovary through the micropylar end occurring double fertilization.
The eyeball is a spherical structure having 2.5 diameters. Structurally, the eyeball has three layers:- sclerotic layer (outer layer); choroid (middle layer) and retina (inner layer).
Outermost layer contains sclera and cornea
Middle layer contains choroid, ciliary body and iris.
Innermost layer consists of retina
Human beings have always been perplexed about the origin and evolution of life on earth. For centuries, a number of theories and hypothesis have been suggested to explain the evolutionary process.
In the previous year, in a very short time life was created by some supernatural power. Most of the religions and civilizations still believe in it, however, they do not have a scientific explanation and more a matter of faith. There has always been an attempt by the scientists and naturalists with keen observation, to explain the evolution scientifically and to look for its evidences.
The process of evolution involves a gradual change or variation in the organisms generation after generation. It means that the organisms of present-day have arisen from ancestors that were simpler in an organisation.
It is a group of viruses that causes respiratory problems in animals and birds. Some viruses are not so dangerous, but due to biological reasons, some family members become lethal causing even death e.g. SARS (Severe acute respiratory syndrome)
MERS (Middle-east respiratory syndrome)
If we see at the sky for some time at night, then we will observe some stars forming groups with shapes. So, the shape formed by the group of stars is called a constellation diagram. The shapes of constellations resemble objects familiar to those people. Each constellation is signified by an animal, a human being, or some other objects it appears to resemble. All the constellations seem to move in the sky from east to west. This is due to the rotation of the earth on its axis from west to east.
The disease is the malfunctioning of the body organs due to one reason or the other. In other words, it is a disorder of the body. The state of the body when any of its normal functions are disturbed or when the structures are altered is called disease. We understand that to remain healthy, we need to do much more than just keep away from disease. CONGENITAL DISEASE: This type of disease is present right from the birth. This is caused either due to genetic disorders or gene mutation or environmental factors. These diseases are passed on from one generation to next generation. Some examples of congenital diseases are Haemophilia, Sickle cell anaemia, Colour blindness, Thalassaemia etc.
All living organisms are made up of a variety of body parts like roots, leaves, flowers, fruits, wood etc. in plants and bones, flesh, nerves etc in animals. These parts look different from each other, yet they are all composed of tiny units called cells. Moreover, many living organisms like Amoeba, Paramecium, Chlamydomonas etc. consist of only one cell.
All living beings are made up of cells. The structural and functional unit of life is a cell which is the building block of the body. New cell arises from the pre-existing cells by the process of cell division.
Cell division occurs in all living organisms. In unicellular organisms, cell division directly produces two individuals. In multicellular organisms or higher-level organisms, life begins from a single cell, as a zygote, whIch divides and redivides mitotically into a number of cells to form a complete organism.
In multicellular organisms, there are two types of cells.
a)The somatic cells or the body cells- They form the body of an organism.
b)The reproductive cells or sex cells- They are gamete-producing cells.
Bacteria are the simplest ,most primitive and unicellular organisms without a true nucleus. That is why they are prokaryotic. they are placed under kingdom Monera. they are found everywhere in air,water,soil,food,inside our body etc. they lack nucleus and other cell organelles of complex cellslike plants,they possess a cell wall. each bacterial cell has its nuclear material in the form of a single chromosome which is not enclosed in a nuclear membrane.
Atoms are too small to see even with a powerful microscope and too light to be weighed even on the most sensitive balance. The history of the discovery of the structure of an atom is fascinating but a complicated subject. Only 100 years ago, scientists believed that atoms were solid, indestructible particles. Since then many great scientists had contributed brilliantly to give us the today’s model of an atom. Over the centuries, many philosophers and scientists tried to develop a model of the atom.
Conduction of water in plants is less elaborate than that of animal as well as plants. Plants are less active, so their cells do not need quick supply of materials. So, the only substances which are to be supplied to a plant through vascular bundle are water and minerals, this process is called ascent of sap. These materials are not available from air. Transport system also helps to carry food prepared in the leaves to the various parts of the plant like stems , roots etc. Ascent of sap is executed by two types of vascular bundles: Xylem which transports water and Phloem which transports prepared food.
On the basis of the function and occurrence ,tissues present in animal body is called animal tissue. These animal tissue is classified into the following four types:
Epithelial tissue
Connective tissue
Muscular tissue
Nervous tissue
The ability of any living organism terms as acclimatization. It develops certain features which improves the chances of its survival in the changing environment. Plants and animals can adopt themselves in such a way that they can easily survive in the conditions where they use to live. We term this phenomenon adaptation also. Acclimatization is a trait of an organism. It favors the living organism by natural selection.
Flowers are the reproductive parts of plants,which are responsible for the production of gametes or sex cells ((non flowering plants).
A flower is modified shoot in which the leaves are modified into floral parts. A blossom propagates a branch from a bud in the axil of a little leaf-like structure called the bract. A bract is commonly green due to presence of chlorophyll and is a very small structure (non flowering plants).
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
1. FLOWER STRUCTURE: EASY DRAWING
AND FUNCTION OF FLOWER
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FLOWER STRUCTURE
DEFINITION OF GAMETES :- Flowers are the reproductive parts of plants,which are responsible for the
production of gametes or sex cells.
A flower is modified shoot in which the leaves are modified into floral parts. A blossom propagates a
branch from a bud in the axil of a little leaf-like structure called the bract. A bract is commonly green due to
presence of chlorophyll and is a very small structure.
FLOWERING PLANTS-NON FLOWERING PLANTS.
Trees that have flowers with stalk of a flower are called flowering plants or angiosperms. There are many
other trees such as pine,firs, redwoods, etc. which do not have flowers and they are called gymnosperms or
naked-seeded plants.
TYPICAL STRUCTURE OF A BISEXUAL FLOWER WITH STALK OF A FLOWER.
Fig#1 simplified diagram of a flower
1. A) Pedicel /Stalk or stalk of a flower
Blossoms are modified as a particular branch at the tip of a stalk known as pedicel or peduncle.
Fig#2 bracts bearing flower in Bougainvillea
2. In some plants such as tulip, there is only one pedicel bearing a single flower.In others , such as lilac the
pedicel is branched and bears many flowers. There are some flowers ( like saffron ) without a stalk .These
flowers are known as sessile flowers.
B) Receptacle ( Thalamus)
The pedicel swells at its tip into a small cup-shaped pad known as receptacle or thalamus. Thalamus can be
flat ,conical,concave or dome- shaped in different shapes.
All the floral whorls along with stalk of a flower arise from the receptacle. The lower part of a blossom are
connected to the receptacle in rings or whorls.
C) Floral Whorls
Generally , a flower consists of four whorls,
The calyx ( the green coloured sepals) on the outside (first whorl)
The corolla ( coloured petals ) lying inside the calyx ( second whorl ).
The androecium ( male parts ) enclosed by the corolla ( third whorl ) and
The gynoecium ( female parts ) at the centre of the flower ( fourth whorl),
D ) Nectaries
Nectar is a sweet fragrant liquid secreted by most of the flowers. These flowers have the nectar secreting
cells, called nectarines. Nectaries are found near the base of the pistil or or on the base of the petals.
Nectar helps cross pollination .In Nasturtinum flowers ,the nectarines are very large and prominent.
COMPLETE AND INCOMPLETE FLOWERS.
* Complete flower:- A flower which has all the four types of floral structures along with stalk of a flower
namely, calyx, corolla, androecium, and gynoecium called complete flower e.g. Hibiscus
* Incomplete flower:- A flower in which any one or more of the four floral parts are missing are called an
Incomplete flower e.g.pumpkin. ( polyadelphous stamen)
ESSENTIAL AND NON-ESSENTIAL PARTS OF A FLOWER.
* Essential ( reproductive ) parts of a flower.:- Those parts of a flower which are directly concerned with
reproduction are known as essential parts of a flower.
For example, stamens ( male parts ) and the carpels ( female parts ) are the essential parts of a flower.
*Non-essential (non-reproductive) parts of a flower) :- Those parts of a flower which directly do not take part
in reproduction are called non-essential parts of a flower.They simply either protecting the reproductive
parts or to make the flower attractive for pollination. For example, sepals and petals are non-essential parts
of the flower.
NON ESSENTIAL PARTS OF A FLOWER.
CALYX.:— THE Calyx is the outermost whorl of the flower. It consists of three to five sepals,which are
generally green in colour and However look like small leaves,that cover an unopened floral bud. However
as in Gulmohar,they may be coloured and are known as petaloid sepals. ( polyadelphous stamen)
MODIFICATION OF CALYX.
3. Fig#3 diagram of modification of calyx
When sepals are free from each other,as in mustard or raddish,they are known as polysepalous or they may
be fused to form a cup in flowers of other plants such as china rose, (gamosepalous).
FUNCTIONS
*the calyx encloses and protects the inner whorls of the flower in the bud stage.
*Since the sepals contain chlorophyll,they can also synthesize food (photosynthesis).
*Together with petals ,they also attract the birds and insects for pollination.
2) COROLLA:- The Corolla is the most conspicuous part in the flower because it is usually white or brightly
coloured. The corolla forms the second whorl from outside,inner to the calyx. This whorl is made up of
petals, which are much larger than sepals. Petal number of flower is different from plant to plant.
Fig#4 diagram of modification of corolla
MODIFICATION OF PETAL :- In some flowers the petals are green in colour,known as sepaloid petals.The
petals may be separate from each other as in mustard flower ( known as polypetalous),or become
partly/completely fused as in petunia ( known as gamopetalous). If the petals are completely fused, they
form a corolla tube
F) FUNCTIONS :-
* The brightly coloured corolla attracts pollinating agent causing cross pollination such as insects and birds.
*Some petals are scented with a nectary which produces sugary nectar. The insects and birds come to
collect this nectar while doing so transfer pollen from one flower to another.
* The corolla encloses and protects the stamens and the pistil.
ESSENTIAL PART
4. Fig#5 diagram of stamen or androecium
A) Androecium :- The Androecium ( Andros meaning male ) forms the third whorl on the inside of the
flower. Androecium consists of stamens. These are the male reproductive organs. Every stamen is
comprised of a thin versatile stalk known as the filament which is fibrous, which holds the anther at its end.
Anther is appended to the filament. With the help of a structure known as the connective. Each anther is two
lobed. Each lobe has two pollen sacs. Thus each anther is made-up of four pollen sacs in which pollen
grains are formed.Pollen grains are fine,powdery,granular structure which contain the male gametes.
Variations in the Androecium.
NUMBER OF STAMENS : The number of stamens may differ greatly in flowers of plants from different
families For example, some grases have only one stamen,Mexican blood trumpet and jacarandas have four
stamens and roses have several dozens.
2.POSITIONS OF STAMENS WITHIN A FLOWER :-The stamens may originate near the base of the pistil
Fig#6 diagram of epipetalous stamen
or they may be fused at their base with the petals and appear to originate out of the petal. For example,in
Petunia flower ,the filaments are attached with the petals and the condition is known as epipetalous.
(FLOWER— THE STRUCTURE AND FUNCTIONS)
STAMENS FUSED OR FREE:-
5. Fig#7 diagram of polyadelphous stamen
Polyadelphous: The stamens may be free and filaments are united,known as polydelphous androecium,for
example mustard,Bombax etc.
Monadelphous: The filaments may be fused and anthers are free,known as monadelphous androecium,for
example peas,beans and Hibiscus.
Fig#8 diagram of monadelphous and diadelphous stamen
Diadelphous : The filaments are united into two bundles and the anthers remain free,known as the
diadelphous stamens,for example, peas,gram,beans.
Fig#9 diagram of syngenesious stamen and synandrous stamen
6. Syngenesious: In some other cases as in sun-flower,the filaments are free but the anthers are united.
(FLOWER— THE STRUCTURE AND FUNCTIONS)
FUNCTIONS,
* The anther produces pollen grains which contain the male reproductive cells,i.e the gametes.
* The filament carrys and supports the anther in the most proper situation for the exchange of pollen dust to
transfer.
B)Gynoecium.
The gynoecium is the fourth and the innermost whorl of a flower. The gynoecium consists of ovule-bearing
basic units called pistils or carpels. Collectively, carpels from the gynoecium, which is referred to as the
female part of the flower because the carpels produce the female gametes. (synandrous stamen)
A flower may have one or more pistils, which consists of :
Ovary : The basal portion is called OVARY which contains the ovules or embryo seeds. The female
gametes develop in the ovule.
Stigma : Area, where the pollen is received, is called the stigma. The stigma is the terminal part of a
carpel which receives the pollen grains.
Style : Often the stigma may be borne on a slender stalk like structure called the style. Style connects
stigma to the ovary.
VARIATIONS IN THE GYNOECIUM. ( ———— are the non-essential parts of a flower)
NUMBER OF CARPELS: –Peas and beans have only a single carpel,which forms a single pistil. Such
gynoecium is known as monocarpellary. It may be bicarpellary,as in mustard flower where two carpels are
present.There may be more than two as in magnolia and lady’s finger,known as polycarpellary.
POSITION OF THE OVARY IN A FLOWER.
Fig#10 diagram of hypogynous flower
HYPOGYNY (THE SUPERIOR OVARY)If the ovary is attached above the attachment of the other three
whorls,I,e, the corolla,calyx and androecium,the ovary is said to be superior ovary and the condition is
known as HYPOGYNY.Such flowers are called hypogynous flowers. Example, China rose, mustard,citrus
etc.
7. Fig#11 diagram of epigynous flower
EPIGYNY :–(THE INFERIOR OVARY) If ovary is below the level of attachment of the three whorls,and the
receptacle completely grows around the ovary,it is called inferior ovary and the condition is known as
EPYGYNY.Such flowers are called Epygynous flowers,example : Sunflower, cucumber etc. ( synandrous
stamen)
Fig#12 diagram of perigynous flower
PERIGYNY:-(THE INTERMEDIATE OVARY OR HALF INFERIOR OVARY) If the ovary is surrounded by a
receptacle which grows to form a cup-shaped structure uo to the midway of the ovary and the other three
whorls sprout from the receptacle rim,the ovary is said to be HALF-INFERIOR, or INTERMEDIATE. Such
condition is known as perigynia and the flowers are called perigynous flowers. Example, : Pea,been etc. ( —
——— are the non-essential parts of a flower)
INFLORESCENCE-ARRANGEMENT OF FLOWERS ON FLORAL STEM.
An INFLORESCENCE is an arrangement of group or cluster of flowers on a branch of a plant.
Inflorescence refers to the way of individual flowers arranged on the axis or floral stem or rachis. (
synandrous stamen)
8. Fig#13 diagram of racemose and cymose inflorescence
Depending upon the arrangement of flowers on the axis, or peduncle may be branched may be branched or
or unbranched. The Inflorescence is of two types—racemose and cymose about which you may know
afterwards.