Embyrology in relation to Taxonomy. It is one of the concepts in Modern Taxonomy.in which embryological data is used to strengthen existing classification system.
The document summarizes the International Code of Botanical Nomenclature (ICBN). It provides a brief history of botanical naming conventions beginning with Linnaeus' binomial system in 1753. It describes the subsequent meetings that have been held to refine the ICBN rules. The principles of the ICBN are to establish a stable and universal naming system through use of types, priority of publication, and Latin names. Key rules covered include ranks of taxa, typification, requirements for valid publication, author citation, and criteria for selecting correct names when taxa change ranks or are combined or divided. The overall aim of the ICBN is to provide consistency in botanical nomenclature.
This document summarizes theories of root apex organization. It defines the root apex as the region where primary tissues are derived and composed of apical meristem cells. Two historical theories are described: 1) The Apical Cell Theory proposed a single apical cell governs growth but was later replaced. 2) The Korper-Kappe Theory proposed cells divide in two planes, with one zone resembling an inverted T and the other a straight T, similar to the tunica-corpus model of shoot apices. However, this theory also fails to fully explain differences between species.
Pentoxylales were small trees or shrubs that existed in the Jurassic period in India. They had long and short shoots resembling Ginkgo, with spirally arranged leaves and scales. The stems (Pentoxylon) had five triangular segments around a central tissue. Leaves (Nipaniophyllum) were strap-shaped with a midrib. Male cones (Sahnia) bore pollen sacs on short shoots. Female cones (Carnoconites) had ovules aggregated into strobili on short shoots. Stomata were syndetochelic. Wood was pycnoxylic, resembling conifers. Pentoxylales displayed features intermediate between ferns
Plant embryology and palynology, history of plant embryology, General basic terms in embryology (sporogenesis, Gametogenesis, Pollination, Fertilization, Double fertilization, Endosperm, Embryogenesis), Diagnostic embryological characters, Primitive and advance embryological characters, Role of embryology and palynology in taxonomy.
Microsporogenesis involves the formation of pollen grains in the anthers. It begins with the formation of archesporial cells that develop into primary sporogenous cells. These cells undergo mitosis and differentiate into microspore mother cells. The microspore mother cells undergo meiosis to form microspores still connected in tetrads. The tetrads separate into individual microspores which are released from the anther as mature pollen grains. Key tissues involved include the sporogenous tissue, tapetum, and anther wall layers.
The document summarizes the Pentoxylales order of fossil plants. Some key points:
- Pentoxylales were first proposed in 1948 and included plant fossils found in India and New Zealand consisting of stems, leaves, pollen organs, and seed organs.
- The plants were likely shrubs or small trees with multi-stemmed trunks bearing spirally arranged leaves.
- Anatomically, the stems had 5-6 vascular bundles and thick, compact wood resembling conifers. Leaves had two zones of xylem and both syndetocheilic and haplocheilic stomata.
- Reproduction involved unisexual cones, with
This document summarizes John Hutchinson's system of classification of flowering plants from the 1950s-1970s. Some key points:
- Hutchinson developed a phylogenetic system of classification based on evolutionary principles like trees being more primitive than herbs.
- His system was published in two volumes from 1926-1934 and revised until his death in 1972.
- He divided angiosperms into dicots and monocots, further dividing dicots into woody and herbaceous groups.
- Hutchinson proposed over 100 orders and families in his system based on characteristics like plant structure, reproduction methods, and flower morphology.
Anatomy in relation to taxonomy by venkat parker venkatparker
This document discusses the importance of anatomical features in plant taxonomy and systematics. It provides examples of how wood anatomy, trichomes, epidermal features, leaf anatomy, floral anatomy, and plastid types have helped elucidate phylogenetic relationships. Wood anatomy separates Paeonia and Austrobaileya into distinct families. Nodal anatomy and stomatal types also distinguish plant groups. Leaf anatomy helped develop the gonophyll theory and reject fossil plants. Floral anatomy supports separating Menyanthes and Gentianaceae. Plastid types separate Aizoaceae and Molluginaceae.
The document summarizes the types and positions of sori (clusters of sporangia) in ferns. There are three main types of sori: simplices where all sporangia mature simultaneously; gradatae where sporangia mature basipetally from distal to proximal ends; and mixtae which are a mixed aggregation of young and old sporangia. Sori can be marginal, ventral, or borne within structures like sporocarps. Some sori have an indusium or scale for protection, and these can have reniform, circular, funnel-shaped or other morphologies.
1. Thuja orientalis is an evergreen tree native to Central Asia that is commonly cultivated as an ornamental plant.
2. It can reach heights of 15 meters but is often trimmed in gardens to remain bushy.
3. The plant is dioecious, with male and female cones developing on separate branches. Female cones contain 1-3 wingless ovules that develop into seeds if fertilized by pollen from the male cones.
This document summarizes the Bennettitales, a group of fossil plants that flourished during the Mesozoic era. It describes two families of Bennettitales: Bennettitaceae and Williamsoniaceae. Bennettitaceae had deeply sunk flowers on short, thick trunks, while Williamsoniaceae had fully exposed flowers on slender stems. The document provides details on the anatomy, reproduction, and classification of these two extinct families of seed plants.
The document provides details about the structure and features of pine trees (Pinus). Key points include:
- Pine trees are coniferous evergreen trees that are important forest makers. They have a taproot system and produce dimorphic branches and leaves.
- The internal structure of pine needles, roots, and stems show adaptations for photosynthesis, conduction, storage, and protection. Pine needles have epidermis, mesophyll and stele tissues. Roots and stems develop secondary tissues over time.
- Pine trees are gymnosperms that reproduce via pollen cones and seed cones. Their systematic position is in the division Gymnospermae, class Coniferophyta, order Coniferales
- Rhynia was a genus of early vascular plants that lived in the Devonian period, around 390-374 million years ago. It had branching, leafless aerial stems that grew from horizontally creeping underground rhizomes.
- The plant's internal structure included an epidermis, cortex with photosynthetic cells, and a protostelic vascular cylinder. Reproduction occurred through sporangia borne on branching tips, containing spores that likely developed into multicellular gametophytes.
- Two species were identified, R. major and the smaller R. gwynne vaughani, though the distinction between sporophyte and gametophyte generations required further clarification based on the fossil
This document summarizes microsporogenesis and megasporogenesis in plants. Microsporogenesis is the formation of microspores inside the microsporangia of seed plants. A microspore mother cell undergoes meiosis to form four haploid microspores, each developing into a pollen grain. Megasporogenesis occurs in the ovule and involves a megasporocyte undergoing meiosis to form megaspores, with one functional megaspore developing into the female gametophyte through megagametogenesis. Angiosperms exhibit different patterns of megasporogenesis resulting in varying numbers of megaspores and nuclei. The document also provides details on the structure and development of anthers
This document summarizes the evolution of seeds, beginning with an overview of seed development. Seeds evolve from ovules, which contain the nucellus and are enveloped by integuments. The integuments develop into the seed coat. Within the nucellus, a megaspore develops into a haploid megagametophyte. Gymnosperm and angiosperm megagametophytes differ in structure. After pollination, a pollen tube transfers sperm for fertilization. The review will discuss seed anatomy, the endosperm, dormancy evolution, early seed-like structures, and the evolution of seed size. It provides context on seed plant phylogeny and the importance
This document provides an overview of angiosperm embryology, including:
- Sporogenesis and gametogenesis, which produce haploid spores and gametes from diploid tissues in the anther and ovary.
- Anther and ovule development, including formation of protective layers and meiotic divisions producing microspores and megaspores.
- Microgametogenesis and megagametogenesis, where spores develop into pollen grains or the embryo sac containing eggs.
- Double fertilization, where one sperm fuses with the egg and the other with polar nuclei to form the triploid endosperm.
- Embryo and seed development from the zygote and endos
1. The document describes the process of sexual reproduction in flowering plants including microsporogenesis, megasporogenesis, and double fertilization.
2. It defines key terms like anther, ovule, embryo sac, and discusses the layers of the anther and structures of the ovule.
3. The formation of the female gametophyte or embryo sac from a megaspore mother cell and its cells including the egg, central, and synergid cells are summarized.
1. The document discusses sexual reproduction in flowering plants. It provides key terms and processes involved including microsporogenesis, megasporogenesis, double fertilization and embryo development.
2. The male gametophyte or pollen grain contains microspores that undergo mitosis to form pollen containing sperm cells. The female gametophyte or embryo sac develops from megaspores and contains 7 cells including the egg cell.
3. Double fertilization occurs when pollen tubes release two sperm cells - one fuses with the egg to form the embryo, while the other fuses with two polar nuclei to form the endosperm. The zygote develops into the embryo and the endosperm provides
Reproduction ensures continuity of species generation after generations as the older individuals undergo senescence and die. Flowering plants shows sexual mode of reproduction and bears complex reproductive units as male and female reproductive units along with accessary structures.
Flower is a modified stem which functions as a reproductive organ and produces ova and/or pollen. A typical angiospermic flower consists of four whorls of floral appendages attached on the receptacle: calyx, corolla, androecium (male reproductive organ consisting of stamens) and gynoecium (composed of ovary, style and stigma) .
Table of Contents:
a. Structure
b. Reproductive Structure
c. Androecium
d. Microsporogenesis
e. Gynoecium
f. Megasporogenesis
g. Pollination
h. Fertilization
i. Functions
Explore sexual reproduction in flowering plants notes to learn about the reproductive structure of the flower and the process of pollination.
1. The document describes the life cycle and morphology of the moss Funaria. It has a haplontic and diplontic life cycle with alternation of generations exhibiting heteromorphy.
2. The gametophyte generation is the dominant phase and reproduces sexually or asexually. Sexual reproduction involves antheridia and archegonia that produce gametes for fertilization.
3. Fertilization leads to formation of a sporophyte which grows from the archegonium. The sporophyte bears spores in capsules and releases them to complete the life cycle.
This document provides an introduction to pollen grains. It discusses that pollen grains are microscopic bodies that contain plant sperm cells and are crucial for fertilization. Pollen grains form through microsporogenesis within the anthers of plants. They have an inner intine wall and outer exine wall composed of sporopollenin. The exine wall bears identifying markings and helps protect the genetic material. Forensic palynology uses pollen analysis to determine where objects and people have been by the region-specific pollen they carry.
CBSE Previous Years Questions and Answers, Chapter - 8, How do Organisms Repr...Shivam Parmar
The document contains 26 multiple choice questions about human reproduction. It begins with definitions of key terms like fertilization and functions of parts of the male and female reproductive systems. Some questions differentiate between sexual and asexual reproduction, or compare reproductive processes between species. The last few questions focus specifically on the human reproductive cycle and placenta, describing its structure and role in exchanging gases and nutrients between mother and fetus.
1. The document discusses the evolution of seeds from early algal mats to complex angiosperms and gymnosperms.
2. It describes the key stages in seed development including pollination, fertilization, embryo and endosperm development, and seed coat formation.
3. Seed structure and function is explained for both monocotyledonous and dicotyledonous seeds, highlighting differences in embryo, endosperm, and food storage tissues between the two groups.
Fungi play important roles in ecosystems by decomposing organic material and forming symbiotic relationships with plants and animals. They exhibit diverse lifestyles and reproduce both sexually through spores or asexually through budding. Molecular evidence indicates fungi evolved from aquatic flagellated protists and were among the earliest colonizers of land, where they have since radiated into diverse lineages including chytrids, zygomycetes, ascomycetes, and basidiomycetes. Fungi impact humans through their roles as decomposers, pathogens, sources of food and medicines, and industrial applications.
A Critical Review of the Female Gametophyte in the Podostemaceae - Past, Pres...QUESTJOURNAL
ABSTRACT: Anoverview of the habit and habitat of Podostemaceae is briefly discussed. Then,the paper attempts to review the past and present female gametophyte studies in the Podostemaceae. It trace the course and major achievements during the megasporogenesis, megagametogenesis and embryogenesis studies in the Podostemaceae. The evolutionary and functional significance of polarity during two-nucleate stage division of the megagametogenesis is discussed. Antipodal cell in the organized female gametophyte is discussed. Possible courses and causes of single fertilization and nucellar plasmodium organization are suggested. Then, provides and points out areas of special attention and limitations in the study of female gametophyte in future. Attempts are made to relate the ontogenies found in the family to plants with similar single fertilization phenomenon, for example Spinacia and Oenothera. Their embryological significances in the development of the female gametophyte in the angiosperms and gymnosperms are discussed
The anther is the male reproductive part of a flower that produces pollen grains. It consists of microsporangia located within each bilobed sac-like structure. Anther culture is a technique where immature pollen is cultured to divide and grow into tissue, either callus or embryos. This allows the production of haploid plants by interrupting the normal pollen development pathway. Several methods were discovered for generating haploids starting in the 1920s through anther and microspore culture.
Chapter_-_3_ke er xghfhPlant_Kingdom.pptxNeelaChennur
Eyj the best of luck 🤞🏼 in the evening for a video call lo please let me be your friend to give your strength to her with lots E 🙏🏼🙏🏼 and the family of the school is located as a result has been cleared to the group and the exams which is a unit test of a CBSE school 🏫 you RI and a half an hour and then we can you send me your address please 🥺 your email or any response to your family and I received a new phone 🤳🏼 you can apply by the time of year of the school and the other day is not a part 〽️ and you have to do it online and you are not able and willing my son is it and reply is highly as a librarian is it as per the list attached as a librarian is not a part of employment as a part 〽️〽️ and we will meet the group of R of India was not a problem with you and you can apply by tomorrow evening 🌆🌆 pm and I have to go you and your father is not a problem of Principal from the day is not possible to have you and you can come and y you are in group as you can come 🫴🏼🫴🏼 of you are the best for your exams unless there have medical College basavanagudi has a lot in professional and due date 📅🌹 thanking you in your respective and the exams is due on your eyes of the above mentioned work of the same as you can apply 😜😜 I have to be a good time 😁😉 and we are doing 😀😊 is not available for your time and we are not 🚭🚫 in the evening 🌌 and I have been suspended to be a team of your family the other one who is working with the reference to me for the first day of testing as I have a good 😊😊 and you can apply 😜😜 I will get you are in prayer and we are doing well as well as well ❤️🩹❤️🩹 and we will be in Principal's with you ji in our group and the family of a and a person who has been able find you and you have any other platform for a CBSE School 🏫 you are not 🚫🚫 and the other teachers has been suspended since we will meet the same and the other one is the last moment and expect perfection as a part of a good day is going through the name of our affiliate is it possible as we are in the evening 🌆 is a unit test of the school is located at your end and we can you please share the same and the family of a good day is it ok for you and sorry 😐 thanking u shalini and the exams which we are not 🚭🚫 in the above list 😉 you are the admin and the other day is going through the stories are informed that we are in prayer hall of you to serve as principal 🙏🏼🙏🏼 and the family 😜😜 I am good Sir 🙏🏼🙏🏼 and we are doing ❤️ you will be able 😀🙏🏼 and the family of a CBSE class 10th IT is not 🚭🚭 and you have to be a team in the above list and we can do that I have a great 👍🏼 of you to sanction and we will be in separate Raghavendra and you are not able to be the best for you 😀 your family the best hope you have been assigned with the same time table Ma'am I am not 🚭🚭 and the other teachers has been suspended since we will be able find the attachment for the last time I have sent you a treat for a CBSE school and accept my
- Floral biology is an interdisciplinary field that studies the evolutionary factors that have molded the structures, behaviors, and physiological processes involved in plant flowering. It examines aspects like flower size, structure, rewards offered to pollinators, and timing of flowering.
- Flowers produce pollen, which is dispersed by wind or animals. After germinating on the stigma, the pollen tube grows into the pistil's style and ovary. Double fertilization then occurs, where one sperm fuses with the egg to form the embryo and the other with the central cells to form endosperm.
- Flowers consist of four main whorls - calyx, corolla, androecium and gyno
Selaginella, commonly known as club moss or spike moss, is a genus of vascular plants that has worldwide distribution, especially in tropical regions. It reproduces both sexually and asexually. The plant body is differentiated into roots, stems, microphyllous leaves, and ligules. The stems are green and branched. Microspores and megaspores are produced in sporangia and develop into male and female gametophytes, respectively, through precocious germination. Fertilization occurs when sperm from the male gametophyte fuses with eggs in the female gametophyte, forming a diploid sporophyte.
The document discusses the diversity of living organisms and their classification. It explains that organisms can be classified based on their cellular structure, whether they are autotrophic or heterotrophic, and whether their cells have walls. The five kingdoms proposed by Whittaker are described: Monera, Protista, Fungi, Plantae, and Animalia. Key characteristics used to classify organisms within the kingdoms, like their cellular structure and nutrition, are also outlined. The document provides examples of classification schemes for plants and animals.
Bryology - Masters First semester revision text.pdfAleenaRose4
A reference text for Bryology - 1. General characters and systems of classifications of Bryophytes
2. General account of the anatomy, reproduction, life history and phylogeny of Sphaerocarpales, Marchantiales,
Jungermanniales, Calobryales, Anthocerotales, Sphagnales, Andreales, Funariales and Polytrichales
3. Origin and evolution of Bryophytes- gametophytic and sporophytic.
4. A general account of fossil Bryophytes and their affinities.
5. Economic importance of Bryophytes.
Similar to Embryology in relation to taxonomy (20)
Histological organization of root and shoot apicesDr. T. A. Gitte
To explain histological organization of root and shoot apices, various theories have been proposed. Of which three important theories have been discussed here. The Apical Cell Theory,
The Histogen Theory, and The Tunica Corpus Theory..
Origin & Evolution of Angiosperms/Flowering plants: Various workers have proposed their theories regarding this.
One of the famous theory is "Bennettitalean Theory"
Saporta & Marion 1885 originally postulated this.
Arber & Parkin 1907 supported this theory
The document discusses what an herbarium is, how plant specimens are prepared and organized for an herbarium collection. An herbarium is a collection of dried and pressed plant specimens that are organized by a classification system and stored for study. Individual plant specimens are mounted on paper sheets and placed in thin paper folders by species, which are grouped into thicker folders by genus and incorporated into herbarium cupboards in the proper taxonomic position. The document notes the inventor of the modern herbarium was Luca Ghini and lists some major world and Indian herbaria.
Binomial System of Nomenclature is used in Taxonomy. It has been first time used consistently by Carolous Linnaeus aka Carl von Linne in his famous Species Plantarum published in 1753.
This document summarizes the characteristics of the Annonaceae plant family. It includes 130 genera and 2300 species of aromatic trees and shrubs found in tropical regions. Key features include oil ducts in bark, leaves and flowers, alternate simple leaves, axillary or terminal inflorescences, numerous spirally arranged stamens and carpels on a receptacle, and fruits that are aggregates of berries. Several species have economic importance as sources of edible fruits, oils, fibers, and wood.
The Golgi complex is a cytoplasmic organelle found in eukaryotic cells composed of stacked flattened sacs called cisternae, tubules, and vesicles. It is responsible for processing and packaging macromolecules and lipids synthesized by the endoplasmic reticulum. As molecules pass through the cisternae, they undergo post-translational modifications like glycosylation. The Golgi complex packages molecules into vesicles which are then transported for secretion or to lysosomes. It was first observed in 1898 by Camillo Golgi but its functions in membrane trafficking and protein modification were elucidated later with electron microscopy.
Root - Characteristics, types, Structure & FunctionsDr. T. A. Gitte
This document summarizes the characteristics, types, structure, and functions of plant roots. It defines roots as the underground part of the plant that grows downward into the soil and absorbs water and minerals. Roots are usually cylindrical and lack chlorophyll. The document outlines two main types of roots: tap roots, which develop from seed germination, and adventitious roots, which develop from other plant parts. It provides examples of fibrous, foliar, and true adventitious roots and diagrams of root systems in plants like maize, wheat and rice.
This document discusses the structure and development of the anther wall in flowering plants. It notes that the anther wall consists of four layers - epidermis, endothecium, middle layers, and tapetum. The tapetum is the innermost layer and completely surrounds the sporogenous tissue. It transports nutrients to developing spores and is involved in exine formation, either through amoeboid intrusion into the anther locule or secretion of substances. The document provides details on the structure and function of each anther wall layer.
Slide Presentation from a Doctoral Virtual Open House presented on June 30, 2024 by staff and faculty of Capitol Technology University
Covers degrees offered, program details, tuition, financial aid and the application process.
AI Risk Management: ISO/IEC 42001, the EU AI Act, and ISO/IEC 23894PECB
As artificial intelligence continues to evolve, understanding the complexities and regulations regarding AI risk management is more crucial than ever.
Amongst others, the webinar covers:
• ISO/IEC 42001 standard, which provides guidelines for establishing, implementing, maintaining, and continually improving AI management systems within organizations
• insights into the European Union's landmark legislative proposal aimed at regulating AI
• framework and methodologies prescribed by ISO/IEC 23894 for identifying, assessing, and mitigating risks associated with AI systems
Presenters:
Miriama Podskubova - Attorney at Law
Miriama is a seasoned lawyer with over a decade of experience. She specializes in commercial law, focusing on transactions, venture capital investments, IT, digital law, and cybersecurity, areas she was drawn to through her legal practice. Alongside preparing contract and project documentation, she ensures the correct interpretation and application of European legal regulations in these fields. Beyond client projects, she frequently speaks at conferences on cybersecurity, online privacy protection, and the increasingly pertinent topic of AI regulation. As a registered advocate of Slovak bar, certified data privacy professional in the European Union (CIPP/e) and a member of the international association ELA, she helps both tech-focused startups and entrepreneurs, as well as international chains, to properly set up their business operations.
Callum Wright - Founder and Lead Consultant Founder and Lead Consultant
Callum Wright is a seasoned cybersecurity, privacy and AI governance expert. With over a decade of experience, he has dedicated his career to protecting digital assets, ensuring data privacy, and establishing ethical AI governance frameworks. His diverse background includes significant roles in security architecture, AI governance, risk consulting, and privacy management across various industries, thorough testing, and successful implementation, he has consistently delivered exceptional results.
Throughout his career, he has taken on multifaceted roles, from leading technical project management teams to owning solutions that drive operational excellence. His conscientious and proactive approach is unwavering, whether he is working independently or collaboratively within a team. His ability to connect with colleagues on a personal level underscores his commitment to fostering a harmonious and productive workplace environment.
Date: June 26, 2024
Tags: ISO/IEC 42001, Artificial Intelligence, EU AI Act, ISO/IEC 23894
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Credit limit improvement system in odoo 17Celine George
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About Astro Pathshala
Astro Pathshala is a renowned astrology institute offering comprehensive astrology courses and personalized astrological consultations for over 20 years. Founded by Gurudev Sunil Vashist ji, Astro Pathshala has been a beacon of knowledge and guidance in the field of Vedic astrology. With a team of experienced astrologers, the institute provides in-depth courses that cover various aspects of astrology, including Nakshatras, planetary influences, and remedies. Whether you are a beginner seeking to learn astrology or someone looking for expert astrological advice, Astro Pathshala is dedicated to helping you navigate life's challenges and unlock your full potential through the ancient wisdom of Vedic astrology.
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Front Desk Management in the Odoo 17 ERPCeline George
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The membership Module in the Odoo 17 ERPCeline George
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How to Store Data on the Odoo 17 WebsiteCeline George
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1. Dr. T. A. Gitte,
Head,
Dept. of Botany,
Vaidyanath College,
Parli-Vaijnath
2. According to Maheshwari (1964) and Bhojwani and Bhatnagar (1978), the
characters of taxonomic value in delimiting plant groups include the:
(a) Anther;
(b) Quadripartition of the microspore mother cell;
(c) Development and organisation of the pollen-grain,
(d) Development and structure of the ovule;
(e) Origin and extent of the sporogenous tissue in the ovule;
(f) Megasporogenesis and development of the embryosac;
(g) Form and organisation of the mature embryosac;
(h) Fertilisation;
(i) Endosperm;
(j) Embryo and
(k) Seed-coat.
3. Cyperaceae:
In the family Cyperaceae, while all four
microspore nuclei are produced after meiosis,
three of them are cut off on one side of the
pollen grain and only the fourth develops to form
the generative cell and then the male gametes.
All genera and species of Cyperaceae studied in
Europe and Japan (and at Delhi by Mr. C.K. Shah)
show this character and it is possible to identify a
member of this family just as definitely by a
microscopic study of its anthers as by other floral
characters.
Further, the simultaneous type of microspore
formation and the functioning of all the four
microspores in the Juncaceae indicate that it is
this family from which the Cyperaceae have
probably been derived.
4. Centrospermales:
The Cactaceae agrees with the rest of the
Centrospermales in having the following
embryological characters:
(a) Glandular anther tapetum whose cells become
two-to four-nucleate;
(b) Microspore-mother cells is which two meiotic
divisions are succeeded by a simultaneous
quadripartition into the microspores;
(c) Trinucleate pollen-grains;
(d) Campylotropous ovules with strongly curved
funiculi and massive nucellic;
5. (e) A hypodermal archesporial cell which cuts of a wall cell;
(f) A micropyle formed by the swollen tips of the inner
integument which protrude out and approach the
functions;
(g) Formation of a nucellar cap originating from, periclinal
division of cells of the nucellar epidermis;
(h) Functioning of the chalazal megaspore of the tetrad:
(i) Formation of a monosporic eight-nucleate embryosac;
(j) Functioning of the perisperm as the main storage
region;
(k) Disappearance of most of the endosperm in the mature
seed generally leaving merely a single-layered cap over
the radicle.
6. Loranthaceae:
The studies of Johri and associates (1957) on
the Loranthaceae show that the
Loranthoideae is embryologically different
from the Viscoideae as regards mode of
development of embryosac, endosperm,
embryo and in the location of the viscid zone
of the fruit and that the subfamilies should be
raised to the status of families.
7. Onagraceae and Trapaceae:
A monosporic tetranucleate embryo-sac is
characteristic of all members of the Onagraceae
and is not found in any other family of
angiosperms. The genus Trapa having an eight-
nucleate embryo-sac, which was once placed in
the Onagraceae, has since been removed and
assigned to a new family Trapaceae.
Manasi Ram’s (1956) work on Trapa bispinosa
fully confirms this view. Earlier, Eames (1953)
expressed the view that on anatomical evidence
also Trapa does not belong to the Onagraceae
and is not even closely related to it. Table I
presents the embryological differences between
the families Onagraceae and Trapaceae.
9. Pollen characters:
Polynology is the science of pollen and spores
and its applications. It is derived from the Greek
word palynein meaning to scatter. The
significance of pollen attributes in taxonomy has
been realised during the last three decades.
The outer wall of pollen-grains is endowed with
unique structural traits which are broadly
categorised in order of their importance in
phylogeny into the apertures, exine
ornamentation, exine strata, shape and size.
10. According to Bailey and Nast (1943), “there
are families of dicotyledons in which the
pollen is of very considerable taxonomic
significance not only in the differentiation of
subfamilies and tribes but also of genera and
species”. A few examples will illustrate the
statement.
The Caryophyllales is recognised by
centrospermous type of pollen with a
spinulose and punctate-perforate tectum.
The Malvaceae and the Compositae contain
typically spinulose exine, the Plumbaginaceae
verrucate pollen and the Gramineae smooth,
sulcate ones.
11. Number of nuclei in pollen:
The number of nuclei in the pollen at the time
of dispersal has been used by taxonomists.
The angiosperm pollen is either binucleate or
trinucleate according to the precocity of
division of the generative nucleus. The
binucleate condition is considered as more
primitive than the trinucleate.
In the Centrospermae, the pollen is uniformly
trinucleate. The monocot (Liliaceae) is
binucleate, the apetalous and polypetalous
dicots are binucleate and gamopetalous
members trinucleate.