Taxonomy introduction, Contributions of Scientists

1. PLANT SYSTEMATICS
(Systematics of Angiosperms)
Presented By:
Thrupthi G.N.
Asst.Professor
M.Sc.Botany

2. Contents
 Introduction
 Plant Classification system
 Artificial system of classification
 Natural system of Classification
 Phylogenetic system of classification
 Contribution of taxonomists to plant classification

3. What is Plant systematics?
 Plant systematics is a science that includes and encompasses
traditional taxonomy; however, its primary goal is to reconstruct the
evolutionary history of plant life.
 It divides plants into taxonomic groups, using morphological,
anatomical, embryological, chromosomal, and chemical data.
 However, the science differs from straight taxonomy in that it
expects the plants to evolve, and documents that evolution.
 Determining phylogeny - the evolutionary history of a particular
group - is the primary goal of systematics.

4. Systems of plant classification
 Artificial system of classification
 Natural system of classification
 Phylogenetic System of Classification

5. Artificial classification system
 When plants are classified for the sake of convenience
only, using some arbitrary or easily observable
characteristics the classification is called artificial.
 Eg: Theophrastus classification of Habit- Herbs, Shrubs
and trees.
 One of the most familiar artificial systems is that of
Linnaeus, where he employed a number of stamens as one
of the important characters in his system of classification.
 He grouped plants into 24 classes.

6. Carolus Linnaeus
 Carl Linnaeus was the famous 1700s Swedish botanist, who produced the fundamental
biological taxonomy — the so-called binomial classification system.
 It is the first step toward today’s taxonomic system.
 Linnaeus’ classification, at its most fundamental, uses the twin “genus, species,”
nomenclature to classify microorganisms.
 He introduced the hierarchy of class, order, genus, and species.
 He provided workable keys for the identification of plants and animals.

7. • The most important publications of Linnaeus related to his system of classification are
systema naturae (1735), Flora Lipponica (1737), Genera Plantarum (1737) and Species
Plantarum (1735).
• Linnaeus mainly employed the characters of stamens and carpels and that is why the
system is called as Sexual system of classification.
• Further- he took into account the number of stamens for classification and so the
system is also named as numerical classification.
• The basis of classification proposed by Linnaeus are as under:
• i) Number of Stamens (I-XI1 classes)
• ii) Size of Stamen (XIV-XV classes)
• iii) Cohesion of filaments into bundles (XVI-XVIII)
• iv) Cohesion of anthers (XIx)
• v) Stamens adnate to ovary (xx)
• vi) Distribution of sex in plants (XXI-XXIII)
• vii) Plant without flower (XxIv)

8. Natural Classification
 Natural systems of classification reflect the situation as it
might have existed in nature.
 This clearly means that all the plant existing today are
related and should be grouped together to form a natural
group.
 The system of Bentham and Hooker is a good example of
Natural System of Classification.

9. Antoine Laurent de Jussieu (1686-1758):
French botanist, 1789- Genera Plantarum.
He classified the plants based on the position of the stamens with respect to ovary
- 15 classes
1. Acotyledons - Class 1
2. Monocotyledons
Stamens hypogynous - class 2
Stamens perigynous - class 3
Stamens epigynous - class 4
3.Dicotyledons
A) Apetalae
Stamens hypogynous - class 5
Stamens perigynous - class 6
Stamens epigynous - class 7

10. B) Monpetalae
Corolla hypogynous - class 8
Corolla perigynous - class 9
Corolla epigynous
Anthers connate Class 10
Anthers free Class 11
C) Polypetalae
Stamens hypogynous - class 12
Stamens perigynous class 13
Stamens epigynous Class 14
D)Declines irregularis (Corolla generally absent and male and female flowers on different plants)- Class 15

11. Robert Brown (1773-1858)
• Scottish botanist, contributed to understanding of morphology of flower and
seeds.
• He was the first person to differentiate gymnosperms from Angiosperms.
• Published Prodromus Florae Novae Hollondiae -1827, by following de Jussieu
classification

12. Augustin Pyrame de Candolle (1778-1841):
French botanist, worked in Switzerland. Published work - Theorie
elementaire de la botanique- 1813 Paris
He divide dicotyledons into two groups - Presence or absence of petals.
I. Vasculares: (with vascular bundles/cotyledons):
Class 1. Exogenae( Dicotyledanae: Vascular bundles in ring, two cotyledons)
A. Diplochylamydae (Flowers with 2 whorls of perianth, calyx and corolla)
Thalamiflorae (Polypetalous and hypogynous)
Calyciflorae (Perigynous or epigynous)
Corolliflorae(Gamopetalous and Hypogynous)
B . Monochylamdae ( Flowers with single whorl of perianth)

13. Class2 : Endogenae (Monocotyledanae, vascular bundles sacttered, cotyledon
one)
A. Phanerogamae (Flowers present)
B.Cryptogamae (Flowers absent, hidden or unknown)
II. Cellulares (Plants without vascular bundles/cotyledons)
Class 1. Foliaceae (leafy and sexual, includes mosses and liverworts)
Class 2. Aphyllae (Leafless and without known sexes, algae, fungi and lichens)
Drawback: Inclusion of vascular cryptogams among monocotyledons.
Works: Prodromus systematis Naturalis Regni Vegetabilis - 1824-1873
Where, he gave explaination of all seed plants

14. Phylogenetic system of classification
 Phylogenetic systems of classification are those where the plants are classified
according to their evolutionary tendencies.
 It may be pointed out clearly that due to incomplete fossil records it is not
possible to claim a system as a perfect phylogenetic one.
 The phylogenetic classification is usually designed on the basis of natural
classification.
 The systems of classification proposed by Engler and Prantl (1887-1915),
Hutchinson (1926-34), (1959 and 1973), and Takhtajan (1964,1969,1973 and 1980)
are excellent examples of phylogenetic classification.

15. Micheal Adanson
Michel Adanson was an 18th-century French botanist who made several significant contributions to the field of
botany. Here is a list of some of his notable contributions in chronological order:
1. Familles des Plantes (1763): Adanson published his most famous work, "Familles des Plantes," in which he
proposed a new system of plant classification based on the structure of the reproductive organs of plants, rather than
the traditional Linnaean system based on flower characteristics.
2. Definition of Genus: Adanson introduced the concept of a genus (plural: genera) in botany. He defined a genus as
a group of species that share a common fundamental structural plan.
3. Theoretical Botany: Adanson's work laid the foundation for the development of theoretical botany, which focused
on the study of plant structure and its implications for classification.
4. African Plant Studies: Adanson made significant contributions to the study of African plants, particularly those
from Senegal. He documented and described many previously unknown species and introduced them to the
European botanical community.

16. Micheal Adanson
5. Taxonomic Principles: Adanson's work emphasized the importance of using a wide range of characters
for plant classification, which included morphological, anatomical, and reproductive features. He
believed that these comprehensive characteristics should be considered when classifying plants.
6. Botanical Nomenclature: Adanson's work contributed to discussions on botanical nomenclature and
the naming of plant species. While his classification system did not gain widespread acceptance, it did
influence later developments in plant taxonomy.
Adanson's contributions to botany, particularly his innovative ideas on plant classification, had a lasting
impact on the field and influenced the work of later botanists and taxonomists

17. Alphonso de Candole
 Alphonse de Candolle was a Swiss botanist who made significant contributions to the field of
taxonomy.
 He is credited with coining the term “taxonomy” and developing a system of plant classification
based on structural criteria.
 In his book, “Théorie élémentaire de la botanique,” published in 1813, he argued that plant
anatomy, not physiology, should be the sole basis of classification.
 Candolle’s criteria provided the empirical foundation for a modern evolutionary history of plants and
his system of plant classification found nearly universal application for half a century, during which
time it served as a model for other systems.
 In addition to his work in taxonomy, Candolle also conceptualized the idea of “Nature’s war,” which
influenced Darwin’s principle of natural selection.
 He believed that multiple species developed similar characteristics that were not present in a
common evolutionary ancestor.

18. Concepts of Taxonomic hierarchy

20. Concepts of Taxonomic hierarchy
Genus:
Genus is a taxonomic rank used to classifying organism based on their similar charecteristics,It is the
classification above the level of species.
 It is the minor category.
 It is one of the names making a binomial
 It is niether Latin or latinised
Species:
It is the basic unit of classification, latin/Latinised, second part of binomial.
Intraspecific categories:
Any category below rank of speceies
Eg:Subspecies, Varieties and forms

21. Species concept:
 Species is lowest form of biological unit - Crombie 1950
 Varied definition over time:
1. As a name in book
2.As a judgement
3. As a group of individuals which in totality of their attributes resemble each otherto a degree usually
regarded as specific.
4. Smallest group with distinctive charecters
5. As discrete and immutable entity of divine origin.
On basis of such definitions, there are 3 types of species concept
1. Nominalistic: Used for nomenclature, used by ICBN
2. Taxonomical species concept:
Morphological: A group of individuals with common morphological charecters.

22. Typological:
species- specere, - appearnce. Aristotle - biological organisms has an “invariant
generalised or idealised pattern shared by all members of the group’’.
Morphogeographical species:
Du Reitz - 1930, A species is a population that has similar morphological charecters with
geographical isolation.
3. Biological species :
Love -1964, 1. Genetical basis of variation, 2. Reproductive mechanism, 3.Hybridisation,
4. Isolating mechanism.
They shouldd show interbredding among individuals of a population
There should be reproductive isolation between members of two separate popultions

23. Family concept:
 Higher category than genus and species and recognised by ICBN.
 Single genera (Cannaceae), or multiple genera
Criteria for a family:
1. Phylogenetic unit
It is an ecological unit - Orchidaceae- Epiphytic, Mycorrhizal association
Must be different and separable from other families by discontinous variation.

24. Botanical Nomenclature
 Linnaeus - 1737
 Augustine de Candole - Theorie Elementaire de la Botanique - account of
plant nomenclature - 1813
 These rules were adopted by ICBN.
 ICBN session- Paris Aug 1867.
 Cambridge Congress -1930- Nomenclature came into useage.
 The current useage of nomenclature came into being - 1978.- 12 th ICBN
congress in Lenigard, Russia (1975).

25. Binomial Nomenclature
 Polynomial system- Eg: Gravellia robusta grandiflora australiana - Polynomial
 Gaspard Bauhin 1560-1624- Two names of plants.
 Distinction between the generic name and specific epithet of the plants.
 Carolus Linnaeus- Species Plantarum- 1753.
 Why latin?
 1. It is specific
 Precise and concise
 Pertinent to the eneds of descriptive phases of natural sciences
 Being a dead language - no political problem

26. International Code of Botanical Nomenclature
(ICBN)
 It is an international code or deed for writing the name of world flora. The
naming of plants
 are following according to the rule of ICBN after its establishment. The ICBN
only deals and
 control to the naming of plants but does not do any work on taxonomy. The
head office of
 ICBN is situated at Atrect in the Netherlands. It has three departments
namely, principles,
 rules and provisions for the governance of the code.

27. A. Principles of ICBN
There are six principles of ICBN for naming of plants
Principle 1:
Botanical nomenclature is independent of zoological and
bacteriologicalnomenclature.
Principle 2:
The application of names of taxonomic groups is determined by means
ofnomenclatural types.

28. Principle 3:
The nomenclature of a taxonomic group is based upon priority of publication.
Principle 4:
Each taxonomic group with a particular circumscription, position, and rank can
bear only one correct name, the earliest that is in accordance with the Rules,
except inspecified cases.
Principle 5:
Scientific names of taxonomic groups are treated as Latin regardless of their
derivation.
Principle 6:
The rules of nomenclature are retroactive unless expressly limited.

29. Rules and recommendation of ICBN
 1. Rank of taxa: The ICBN provides the series of rank with names which are the hierarchial catagories.
 2. Rule 2- Type method:
Holotype: One specimen or element used or designated by the author in the original publication as the main
nomencaltural type. Any type after publication cannot be considered Holotype.
Isotype: Duplicate specimen of a holotype. They are plants forming part of the same gathering as the holotype
or growing with it / gathered with it.
Syntype: A syntype is one or two or more specimens studied and cited by the author, when holotype is not
designated by him
Paratype: Specimen cited with original description in addition to the holotype.
Lectotype/Neotype: When author fails to designate a holotype, or holotype is missing.
Lectotype: Specimen selected from those cited by the author with the original description.
Neotype: Specimen selected from the material that was not cited by the author with the original description

30. Rule 3 Priority of Names
1.Priority is concerned with the precedence of the date of valid
publication and determines acceptance of one of two or more
names that are otherwise acceptable.
2.A name is said to be legitimate if it is accordance with the rules
and illegitimate if it is contrary.

31. Rule 4 Effective and Valid Publications of Names
1. The names of taxa must meet the requirement of the Code when it is published.
2. It is effective under this code only when the distribution of printed is performed properly.
3. It should beeffectively published i.e. in a journal
4. It should be published inacorrect form i.e.Latinized with rank indicated and with Latin description
(maybein brief).
5. More detailed description is given in vernacular language.
6. For the taxa of the rank of genus and below.
7. Nomenclature type must be indicated and location ofthe type also indicated.
8. If the names are published effectively and validly using the rules of ICBN then the names are legitimate
otherwise they are illegitimate.
9. The name ofthe newly described taxon is usually indicated by words sp.nov (species nova);gen.nov.(genus
novum)