The document summarizes the recent APG system of plant classification which is based on phylogenetic analysis of DNA sequences and morphological data. It outlines the main clades recognized in the system including basal angiosperms containing Amborellaceae, Nymphaeales and monocots. Magnolids contain four orders while eudicots are divided into basal and core eudicots. Core eudicots include rosids and asterids, with rosids further divided into eurosids I and II. Each clade contains representative orders and families. The APG system strictly follows the principle of monophyly and is based on evidence from multiple sources, though some limitations remain regarding placement of some families.
Angiosperm Phylogeny Group classification
APG I
APG II
APG III
APG IV
Molecular Based system
features and organization
Merits and demerits
Difference in APG system.
From its initiation in 1998, the Angiosperm Phylogeny Group (APG) has focused on the production of an ever-more stable system of classification of the flowering plants (angiosperms). Based largely on analyses of DNA sequence data, the system is compiled by a larger group of experts than any previous system and has the advantage of being testable, allowing for confidence levels in the system to be estimated for the first time.
Angiosperms are the flowering plants also known as Magnoliophyta. The botanical term "Angiosperm" meaning ‘bottle or vessel’ is derived from the ancient Greek. These are the most diverse group of land plants. Angiosperms are seed-producing plants and the distinguished features of angiosperms over gymnosperms are angiosperms bear flowers, endosperm within the seeds and the production of fruits that contain the seed. According to the botanists the flowering plants diversified and widespread 120 million years ago. The classification of the flowering plants also has a long history.
In the past, classification systems were typically produced by an individual botanist or by a small group resulting large number of systems. Different systems and their updates were generally favored in different countries. Bentham and Hooker’s system was popular in the Britain and the Engler’s system was famous in the Europe etc. These systems were introduced before the availability of genetic evidences and angiosperms were classified using their morphology and biochemistry. After the 1980’s genetic evidences were available and phylogenetic methods came into the classification procedures.
In the late 1990s, an informal group of researchers from major institutions worldwide came together and they established the Angiosperm Phylogeny Group (APG). The objective was to provide a widely accepted and more stable point of reference for angiosperm classification. APG I was published in 1998 as their first attempt in Annals of the Missouri Botanical Garden. The initial 1998 paper by the APG made angiosperms the first large group of organisms to be systematically re-classified primarily on the basis of genetic characteristics. The group emphasized the need for a classification system for angiosperms at the level of families, orders and above. The existed systems are rejected is because they are not phylogenetically classified. The outline of a phylogenetic tree of all flowering plants became established and several well supported major clades involving many families of flowering plants were identified. The new knowledge of phylogeny revealed relationships in conflict with the then widely used modern classifications.
The principles of APG system are retaining the Linnean system of orders and families, Use of monophyletic groups (Consist of all descendants of a common ancestor), taking a broad approach to defining the limits of groups such as orders and families and use of term ‘clades’ above or parallel to the level of orders and families. A major outcome of the classification is the disappearance of the traditional division of the flowering plants into two groups, which are monocots and dicots.
Even though there are several controversies about APG the botanists worldwide are influenced by the concept and are currently practice the system.
Angiosperm Phylogeny Group classification
APG I
APG II
APG III
APG IV
Molecular Based system
features and organization
Merits and demerits
Difference in APG system.
From its initiation in 1998, the Angiosperm Phylogeny Group (APG) has focused on the production of an ever-more stable system of classification of the flowering plants (angiosperms). Based largely on analyses of DNA sequence data, the system is compiled by a larger group of experts than any previous system and has the advantage of being testable, allowing for confidence levels in the system to be estimated for the first time.
Angiosperms are the flowering plants also known as Magnoliophyta. The botanical term "Angiosperm" meaning ‘bottle or vessel’ is derived from the ancient Greek. These are the most diverse group of land plants. Angiosperms are seed-producing plants and the distinguished features of angiosperms over gymnosperms are angiosperms bear flowers, endosperm within the seeds and the production of fruits that contain the seed. According to the botanists the flowering plants diversified and widespread 120 million years ago. The classification of the flowering plants also has a long history.
In the past, classification systems were typically produced by an individual botanist or by a small group resulting large number of systems. Different systems and their updates were generally favored in different countries. Bentham and Hooker’s system was popular in the Britain and the Engler’s system was famous in the Europe etc. These systems were introduced before the availability of genetic evidences and angiosperms were classified using their morphology and biochemistry. After the 1980’s genetic evidences were available and phylogenetic methods came into the classification procedures.
In the late 1990s, an informal group of researchers from major institutions worldwide came together and they established the Angiosperm Phylogeny Group (APG). The objective was to provide a widely accepted and more stable point of reference for angiosperm classification. APG I was published in 1998 as their first attempt in Annals of the Missouri Botanical Garden. The initial 1998 paper by the APG made angiosperms the first large group of organisms to be systematically re-classified primarily on the basis of genetic characteristics. The group emphasized the need for a classification system for angiosperms at the level of families, orders and above. The existed systems are rejected is because they are not phylogenetically classified. The outline of a phylogenetic tree of all flowering plants became established and several well supported major clades involving many families of flowering plants were identified. The new knowledge of phylogeny revealed relationships in conflict with the then widely used modern classifications.
The principles of APG system are retaining the Linnean system of orders and families, Use of monophyletic groups (Consist of all descendants of a common ancestor), taking a broad approach to defining the limits of groups such as orders and families and use of term ‘clades’ above or parallel to the level of orders and families. A major outcome of the classification is the disappearance of the traditional division of the flowering plants into two groups, which are monocots and dicots.
Even though there are several controversies about APG the botanists worldwide are influenced by the concept and are currently practice the system.
Gnetum: A Powerpoint Presentation on Gymnospemsshivduraigaran
The Gymnosperms are a group of seed-producing plants (spermatophytes) that includes conifers (Pinophyta), cycads, Ginkgo, and gnetophytes. The term "gymnosperm" comes from the Greek composite word γυμνόσπερμος (γυμνός gymnos, "naked" and σπέρμα sperma, "seed"), meaning "naked seeds". The name is based on the unenclosed condition of their seeds (called ovules in their unfertilized state). The non-encased condition of their seeds stands in contrast to the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or solitary as in Yew, Torreya, Ginkgo.
The gymnosperms and angiosperms together compose the spermatophytes or seed plants. The gymnosperms are divided into six phyla. Organisms that belong to the Cycadophyta, Ginkgophyta, Gnetophyta, and Pinophyta (also known as Coniferophyta) phyla are still in existence while those in the Pteridospermales and Cordaitales phyla are now extinct.
By far the largest group of living gymnosperms are the conifers (pines, cypresses, and relatives), followed by cycads, gnetophytes (Gnetum, Ephedra and Welwitschia), and Ginkgo biloba (a single living species). Roots in some genera have fungal association with roots in the form of micorrhiza(Pinus), while in some others(Cycas) small specialised roots called coralloid roots are associated with nitrogen fixing cyanobacteria.
Gnetum is a genus of gymnosperms, the sole genus in the family Gnetaceae and order Gnetales. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms, they possess vessel elements in the xylem. Some species have been proposed to have been the first plants to be insect-pollinated as their fossils occur in association with extinct pollinating scorpion flies. Molecular phylogenies based on nuclear and plastid sequences from most of the species indicate hybridization among some of the Southeast Asian species. Fossil-calibrated molecular-clocks suggest that the Gnetum lineages now found in Africa, South America and Southeast Asia are the result of ancient long-distance dispersal across seawater
This PPT offers a birds' eye view of the Angiosperm Phylogeny Group III to cover the course content and its complexity.It also covers the emerging trend of the plants taxonomic domain.
* The Gymnosperms originated in the Devonian period of the Palaeozoic Era and formed the supreme vegetation in the Mesozoic Era.
* It was Robert Brown (1827) who first recognised gymnosperms as a separate entity among plant kingdom.
Classification denotes the arrangement of a single plant or group of plants an distinct category following a system of nomenclature, and in accordance with a particular and well established plan.
Pteridophyta or Pteridophytes are Vascular Plants (also known as "seedless plants") that reproduce and disperse via spores. They do not produce either seeds or flowers.
Additional info:
+ Division Equisetophyta (horsetails & scouring rushes)
+ Division Psilotophyta (whisk ferns)
(This is our report in Botany 2.)
Made by: Sharmine Ballesteros (BS Biology 2A2-1)
evidences of anatomy, cytology and chemistry to plant taxonomynasira jaffry
taxonomy is based on other disciplines of sciences. in this presentation, there is discussion how anatomy, cytology and chemistry influnces the taxonomy
This presentation was given by Dr. Avishek Bhattacharjee in Botanical Nomenclature Course held in Botanical Survey of India, Eastern Regional Centre, Shillong in November 2016. This may be helpful to the undergraduate and post graduate Botany students to understand different types of taxonomic literature, especially Flora, Revision and Monograph.
Plant Taxonomy with the passage of time deserves holistic approach in the domain of biology.Now, it becomes a synthetic science due to application of other branches of knowledge like Chemistry, Molecular biology etc.This slide is intended to UG & PG students of Botany.
This presentation has been intended to offer a bird's eye view about the phylogenetic classification of the plant kingdom in general and the Engler and Prantl system in particular with merits and demerits.
Gnetum: A Powerpoint Presentation on Gymnospemsshivduraigaran
The Gymnosperms are a group of seed-producing plants (spermatophytes) that includes conifers (Pinophyta), cycads, Ginkgo, and gnetophytes. The term "gymnosperm" comes from the Greek composite word γυμνόσπερμος (γυμνός gymnos, "naked" and σπέρμα sperma, "seed"), meaning "naked seeds". The name is based on the unenclosed condition of their seeds (called ovules in their unfertilized state). The non-encased condition of their seeds stands in contrast to the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or solitary as in Yew, Torreya, Ginkgo.
The gymnosperms and angiosperms together compose the spermatophytes or seed plants. The gymnosperms are divided into six phyla. Organisms that belong to the Cycadophyta, Ginkgophyta, Gnetophyta, and Pinophyta (also known as Coniferophyta) phyla are still in existence while those in the Pteridospermales and Cordaitales phyla are now extinct.
By far the largest group of living gymnosperms are the conifers (pines, cypresses, and relatives), followed by cycads, gnetophytes (Gnetum, Ephedra and Welwitschia), and Ginkgo biloba (a single living species). Roots in some genera have fungal association with roots in the form of micorrhiza(Pinus), while in some others(Cycas) small specialised roots called coralloid roots are associated with nitrogen fixing cyanobacteria.
Gnetum is a genus of gymnosperms, the sole genus in the family Gnetaceae and order Gnetales. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms, they possess vessel elements in the xylem. Some species have been proposed to have been the first plants to be insect-pollinated as their fossils occur in association with extinct pollinating scorpion flies. Molecular phylogenies based on nuclear and plastid sequences from most of the species indicate hybridization among some of the Southeast Asian species. Fossil-calibrated molecular-clocks suggest that the Gnetum lineages now found in Africa, South America and Southeast Asia are the result of ancient long-distance dispersal across seawater
This PPT offers a birds' eye view of the Angiosperm Phylogeny Group III to cover the course content and its complexity.It also covers the emerging trend of the plants taxonomic domain.
* The Gymnosperms originated in the Devonian period of the Palaeozoic Era and formed the supreme vegetation in the Mesozoic Era.
* It was Robert Brown (1827) who first recognised gymnosperms as a separate entity among plant kingdom.
Classification denotes the arrangement of a single plant or group of plants an distinct category following a system of nomenclature, and in accordance with a particular and well established plan.
Pteridophyta or Pteridophytes are Vascular Plants (also known as "seedless plants") that reproduce and disperse via spores. They do not produce either seeds or flowers.
Additional info:
+ Division Equisetophyta (horsetails & scouring rushes)
+ Division Psilotophyta (whisk ferns)
(This is our report in Botany 2.)
Made by: Sharmine Ballesteros (BS Biology 2A2-1)
evidences of anatomy, cytology and chemistry to plant taxonomynasira jaffry
taxonomy is based on other disciplines of sciences. in this presentation, there is discussion how anatomy, cytology and chemistry influnces the taxonomy
This presentation was given by Dr. Avishek Bhattacharjee in Botanical Nomenclature Course held in Botanical Survey of India, Eastern Regional Centre, Shillong in November 2016. This may be helpful to the undergraduate and post graduate Botany students to understand different types of taxonomic literature, especially Flora, Revision and Monograph.
Plant Taxonomy with the passage of time deserves holistic approach in the domain of biology.Now, it becomes a synthetic science due to application of other branches of knowledge like Chemistry, Molecular biology etc.This slide is intended to UG & PG students of Botany.
This presentation has been intended to offer a bird's eye view about the phylogenetic classification of the plant kingdom in general and the Engler and Prantl system in particular with merits and demerits.
The APG system (Angiosperm Phylogeny Group system) is the first version of a modern, mostly molecular-based system of plant taxonomy.
Published in 1998 by the Angiosperm Phylogeny Group, it was replaced by the improved APG II in 2003, APG III system in 2009 and APG IV system in 2016.
It describes the basics of Plant classification, morphological, anatomical, palynological, embryological, chemical and cytological evidences of classification
Plant taxonomic keys are important for plant identification for students and budding taxonomists. The PPT gives a brief insight into few basic identification plant characters
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
For more information, visit-www.vavaclasses.com
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
3. A BRIEF INTRODUCTION
Earlier plant classification ----- Artificial system.
From 1990’s started using --- Phylogentic analysis to classify the
plants.
Phylogenetic character used for Classification are:
Rapidly accumulating DNA sequences from the plastid gene rbc L
(this gene codes for large subunit of RUBISCO ENZYME).
cp DNA mat K gene ( maturase enzyme encoding gene located with
in the intron of chloroplast trn K gene).
Mitochondrial gene atp A (atp genes providing information for
making transporter proteins called ATPases) and 18 Sr DNA (satellite
related DNA) gave informative data useful in plant classification
Further development of polymerase chain reaction techniques
which help in bio-chemical as well as anatomical analysis has paved a
way for a new system of plant classification.
5. Preface of the APG System of classification
According to traditional system of classification Angiosperms are divided
into Monocots and Dicots based on presence of one or two cotyledons.
But recent study based on Phylogentic analysis ie., nuclear, plastid and
mitrochondrial DNA sequences and morphology do not support this
dicotomy.
Dicots earlier were considered Monophyletic in origin but present study
indicates in the Polyphyletic origin.
Monocots are considered as a Holophyletic group.
A majority of dicots showing similar characters are grouped in to one
branch called the Eudicots or Tricolpates (flowers with 4 or 5 sepals/
petals, tricolpate pollen etc).
The remaining dicots are grouped informally into Paleodicots
6. The APG system of classification proposed in 1998(APG 1,1998)by
The systematists
B. Bremer,
] K. Bremer,
M.W. Chase
J.L. Reveal
D.E. Soltis,
P.S. Soltis and P.F. Stevens
.
It compromised 462 Families arranged in to 40 Monophyletic orders
under a small number of informal higher groups:
Monocots,
Commelinoids
Eudicots,
Core eudicots,
Rosids,
Eurosids I
Eurosids II,
Asterids,
Euasterids I and Euasterids II.
Austrobaileyales order which is unassigned in kept at the beginning.
7. 11 unclassified families and four orders with no supra ordinal
groups were kept at the beginning of the classification.
25 families of uncertain position were kept at the end of the
classification.
Judd et al. (1999) made few modifications in APG-1 classification
by recognising a total of 51 orders by shifting a few families from
informal groups.
This classification includes only major families hence nearly 200
families were left out.
APG II (2003), a recent revision includes 470 families under 45
orders of which 44 are monophyletic and Austrobaileyales order
which is unassigend in kept at the beginning
8. HEIRARCHY OF APG CLASSIFICATION
Recognition of plants based Monophyletic groups called CLADES at all
levels.
The hierarchy of the classification is as follows-
Informal groups
Orders
Families
The informal groups include-
Basal Angiosperms,
Magnolids,
Eudicots,
Rosids
Asterids.
According to APG II ‘Monocots’ is considered Monophyletic group
placed under Basal Angiosperms.
9.
10. CLADE 1: BASAL ANGIOSPERMS
They represent a clade that includes following groups-
Amborellaceae,
Nymphaceae,
Austrobaileyales,
Ceratophyllales,
Monocots.
Amborellaceae: the monotypic Amborella trichopoda --the most basal
linkage to all basal angiosperms with spirally arranged floral organs, ethereal
oil cells.
Nympheaceae: 8 Genera, cosmopoliton in distribution and is consistent with
the fossil records.generally aquatic in habitat, also found in tropical and
temperate regions.
The floral diversity ranges from small, simple, trimerous
flowers(Cabomba) to large, showy, elaborate flowers(Nympheae, Victoria).
Austrobaileyales : represented by Austrobaileyaceae and Trimeniaceae
from Australia and recently added Schizandraceae and Illicaceae.
Ceratophyllales: based on phytogentic analysis based on rbcL.
Ceratophyllum is considered as ‘sister’ of all other Dicots.
11. MONOCOTS---considered as the major clade among extant
angiosperms and also the oldest among the angiosperm fossils
comprises of 52,000 species (22% of the total angiosperms.)
Orchidaceae and Poaceae are the largest families accounting to 34% and
17%.
Ray identified Monocots based on single character ie,. Presence of single
cotyledon but phylogenetic studies of non molecular data include 13 similar
identifying characters
----single cotyledon, parallel veined leaves, sieve cell
plastid with several cuneate protein crystals, secondary vascular bundles in
the stem, adventitious root system and sympodial growth.
Earlier trimerous condition was considered as unique feature in Monocots,
but it is also observed in Nympheaceae and magnolids.
APG II considers Monocots as a monophyletic group with 10 orders and 2
unassigned families(Petrosaviaceae and Dasypogonaceae).
The orders include – Acorales, Alismatales, Asparagales, Dioscorales,
Liliales, Pandanales, Arecales, Poales, Commelianales, and
Zingeberales.
Molecular analysis shows that Acorus as sister to all other Monocots
12. CLADE 2:-MAGNOLIDS
‘Primitive Angiosperms’ with 4 orders according to APG II viz. Piperales,
Canellales, Magnoliales and Laurales.
characterized by the presence of primitive characters like long, broad, net-
veined leaves, large flowers, numerous petals , sepals, stamens and carpels,
Magnoliales: based on molecular analysis includes 6 families such as
Magnoliaceae, Annonaceae, Myristicaceae etc.
----common character i.e. deletion of Apetela 3 gene.&
characterized by presence of reduced fibre pits, palisade parenchyma, continuous
tectum in the pollen etc.
Laurales: includes 7 families characterized by the presence of perigynous
flowers, gynoecium embedded in fleshy receptacle, inner staminodes, ascendant
ovules etc.
Piperales: includes 4 families with characters such as distichous leaves,single
prophyll & oil cells.
Canellales: includes 2 families viz. Canellaceae and Winteraceae. The family
Winteraceae is considered as most primitive extant Angiosperm.
13. CLADE 3: -EUDICOTS
Eudicotyledons (Doyle and Hotton) also termed as Tricolpates or Non-
magnolids (represent 75% of the total Angiosperm population)
Includes 2 groups‘Basal Eudicots’ and ‘Core Eudicots’.
Basal Eudicots: includes five lineages viz
Ranunculales,
Proteales,
Sabiaceae,
Trochodendraceae
Buxaceae.
Core Eudicots: includes seven major clades viz.
Gunnerales,
Berberidopsidales,
Saxifragales,
Santanales,
Caryophyllales,
Rosids
Asterids.
The molecular data supports the fact that Gunnerales is the sister to the
other core eudicots.
14. CLADE 4: -ROSIDS
This clade includes 140 families having common characters like
nucellar endosperm , reticulate exine, tricolpate pollen, simple
perforations of vessel end walls, mucilaginous leaf epidermis, two or
more whorls of stamens, ellagic acid.
Molecular analysis reveals two large sub clades i.e. Eurosids
I(fabids) and Eurosids II(malvids).
A few orders that do not fit into both the
sub clades include : Crossosomatales, Geraniales and Myrtales.
The Eurosids I include Celestrales, Zygophyllales, Malpighiales,
Oxalidales.
Other orders like Fabales, Cucurbitales, Rosales, Fagales form the
‘nitrogen fixing clade’.
The Eurosid II compromises of Brassicales ,Malvales, Sapindales
and Tapiasciaceae.
15. CLADE 5: - ASTERIDS
This is also a large clade with 114 families, 10 orders and 80,000
species.
This group is recongnized based on morphological as well as chemical
data which include iridoid chemical compounds, sympetalous corolla,
unitegmic and tenuinucellate ovules and cellular endosperm.
Previously considered as a polyphyletic group, Asterids are now
considered as monophyletic group based on analysis of three genes rbc
L, atp B and mat K.
Asterids now include four major groups viz. Cornales, Ericales,
Euasterids I(lamids) and Euasterids II(campanulids).
16. Merits of the APG classification
The APG classification system strictly adopts the phylogenetic
principle of monophyly
The APG classification system strictly adopts the phylogenetic
principle of monophyly
The APG classification system strictly adopts the phylogenetic
principle of monophyly
The APG classification system strictly adopts the phylogenetic
principle of monophylyThe APG classification system strictly adopts the phylogenetic
principle of monophyly – reconstructing the phylogeny on the
basis of established monophyletic
The APG classification system strictly adopts the phylogenetic principle ofThe APG classification system strictly adopts the phylogenetic principle of
monophyly .monophyly .
It is based on the synthesis of information derived from multiple sources –It is based on the synthesis of information derived from multiple sources –
morphology, anatomy, embryology, palynology, phytochemistry, molecular biology,morphology, anatomy, embryology, palynology, phytochemistry, molecular biology,
etc.etc.
Formal names have been given only to those groups (i. e. orders) where monophylyFormal names have been given only to those groups (i. e. orders) where monophyly
has been firmly established.has been firmly established.
In order to overcome the problem of paraphyly,In order to overcome the problem of paraphyly, the traditional separation ofthe traditional separation of
angiosperms into monocots and dicots has been discarded. Various monocotangiosperms into monocots and dicots has been discarded. Various monocot
groups have been placed in between primitive dicots and advanced dicots, e. g.groups have been placed in between primitive dicots and advanced dicots, e. g.
Poales are placed in between Magnoliales and Ranunculales.Poales are placed in between Magnoliales and Ranunculales.
17. Cladograms – evolutionary diagrams - based on morphological and molecularCladograms – evolutionary diagrams - based on morphological and molecular
data are presented for showing the phylogenetic relationships, both within anddata are presented for showing the phylogenetic relationships, both within and
among the monophyletic groups.among the monophyletic groups.
The orders, such as Amborellales, Nymphaeales, Austrobaileyales,The orders, such as Amborellales, Nymphaeales, Austrobaileyales,
Chloranthales, which show several primitive features, are placed at the start of theChloranthales, which show several primitive features, are placed at the start of the
APG classification.APG classification.
The number of unplaced and uncertain families has been gradually reduced fromThe number of unplaced and uncertain families has been gradually reduced from
APG-I (40) to APG-III (10).APG-I (40) to APG-III (10).
Based on the recent advances in research. The APG classification is increasinglyBased on the recent advances in research. The APG classification is increasingly
becoming an authoritative point of reference and a significantbecoming an authoritative point of reference and a significant
number of major herbaria, including Kew, Harvard, etc. are arranging their plantnumber of major herbaria, including Kew, Harvard, etc. are arranging their plant
specimen collections in accordance withspecimen collections in accordance with APG.
18. Demerits of APG Classification
APG classification is restricted at the taxonomic levels of only
order and family.
The classification may seem to be sound in theory, but it has
still found few followers in practice.
Although majority of families or genera have been recognised
as monophyletic orders, yet there are several unplaced
families or genera in APG – III.
The orders have been recognised under informal groups
(e.g. Magnoliids, Eudicots, etc), the names of which do not
conform to the ICBN.
Angiosperms have been given the rank of a division, followed
by the rank of order. In contrast to the previous classification
systems, there are no formal taxa between the rank of
division and order.