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.

1. Angiosperm Phylogeny Group(APG) III
N.Sannigrahi,Associate Professor,Nistarini College,
Purulia (W.B) 723101, India
During the post -Darwinian system of classification, a breakthrough
appeared in the 1990s due to large analysis of flowering plants
based on DNA sequences published. Major developments of DNA
sequencing technology & computing power brought a new
momentum due to comprehensive analysis of data of semantides in
general & DNA in partcular.In 1993, a landmark publication
brought a new dimension in the domain of plant taxonomy having
analysis of 500 flowering plants by Mark Chase & 41 co-workers
based on the major genes involved in photosynthesis .A
computation brought a mixed feelings of expectation &
unexpectation. The monocots appeared as a group but the dicot did
not. The foundation of another classification-APG came into the
limelight

2. APG-ANGIOSPERM PHYLOGENY
GROUP
• In 1990, an informal group of botanists almost all
over the world took an initiative to analyze the plant
genetic material under the title of Angiosperm
Phylogenic Group –APG with an intention to provide
a widely accepted & more stable point of reference of
angiosperm plant classification in 1998. as APG I.
Three revisions have been published-APG II on
2003,APG III on 2009, APG IV on 2016, each
superseding the previous systems.

3. Introduction
• The existing systems rejected because not of the
phylogenetic, not strictly based on monophyletic
origin (all the descendents arise from common
ancestor). APG showed that monocot are
monophyletic but majority of the dicot are
monophyletic called eudicots or tricolpates. Of the
remaining dicot species, most belong to a third clade
known as Magnoliidae.
• The rest include a paraphyletic groupings of primitive
species collectively as basal angiosperms plus the
families of Cerotophyllaceae & chloranthaceae.

4. PRINCIPLES OF APG
• The principles of APG were introduced since the
inception in 1998 and it has remain unchanged as far as
principles are concerned until date.
• The Linnaean principles of orders & families remain
unchanged, to be retained & the family is the central in
flowering plant systematics.
• The groups should be monophyletic(Consist of all
descendents of a common ancestor).The main reason why
the existing systems are rejected because they do not have
this property, they are not phylogenetic.
• Families with a single genus and orders having single
family are avoided where this is possible without
violating the over-riding requirement of monophyly.

5. url of the APG III
• APG III 2009 “ An update of the angiosperm
phylogeny group Classification for the orders and
families of flowering plants:APG III’, botanical
Journal of the Linnaean Society 162 (2):105-121
• Search in Google for detail analysis if interested.
• The system is so diverse for its complexity and
vastness and was superseded by APG IV in 2016.
• The phylogenetic approach is a novel one as far as its
approach is concerned.

6. Application of APG
• The APG publications are increasingly regarded as an
authoritative point of reference.
• A significant number of major herbaria, including
Kew are changing the order of their collections in
accordance with APG.
• The influential World Checklist of selected Plant
families is being updated to the APG III system.
• In the USA, a recent photographic survey of the
plants of the USA and Canada is organized according
to the APG II system.
• The Flora of Nepal is planning to follow APG system
following the footprints of UK, USA & others

7. KEY POINTS OF APG III
• The APG III is the updated version of APG II ,2003
• The broad outline of the system remains unchanged,
but the number of previously unplaced families and
genera is significantly reduced. This requires the
recognition of both new orders and new families
compared to the previous classification.
• The APG III system recognized all of the 45 orders of
the previous system as well as 14 new ones and the
total orders reaches to 59.
• Only 10 families are not placed in the order and only
two of these-Apodanthaceae & Cynomoriaceae are
left entirely outside the classification.

8. Contd-----
• The designation o f the alternative “bracketed
families "was abandoned in APG III, because its
inclusion in the previous system had been
unpopular.APG III recognized 415 families, 42 fewer
than in APG II.
• 44 of 55 “bracketed families” were discontinued, and
18 other families were discontinued as well. The
Agavaceae & Hyacinthaceae are no longer regarded
as distinct from the broader Agavaceae family.
• The classification of the families in APG III which
uses formal taxonomic ranks; previously only
informal clade names have been tried to use above the
ordinal level.

9. MERITS & DEMERITS
• The molecular based of plant taxonomy being
developed by Angiosperm Phylogeny group
Merits:
1.It adopts the phylogenetic principle of monophyly.
2.It has derived information from sources like
morphology, embryology, molecular biology, anatomy,
palenology & phyto chemistry.
3.Formal names are given only where monophyly has
been firmly established.
4.It is based on the recent advances in research and is
gaining authority.

10. DEMERITS
• 1. It is limited to the taxonomic level of order &
family.
• 2.It is not popular due to its vastness & complexity.
• 3.several families or genera have not been placed yet.
• 4.The orders are recognized under informal groups
like Magnoliids, Eudicots.These names do not
conform to the ICBN.
• THANK YOU