Taxonomic Systems in Plants

Md. Sajjad Hossain Tuhin

Student ID: 100510

4th year, 1st term

Forestry and Wood Technology Discipline

Khulna University

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Plant systematics

Classification of plants is a very ancient topics.

First plant classification reported in Vedas around 2000 BC.

Classification means the divination of something by the basis of some

properties.

Plant systematics is the branch of botany that is concerned with the naming,

identification, evolution, and classification of plants.

According to Stuessy 1990 “Systematics is a related term, sometimes used

synonymously, but involves a broader discipline of discovering phylogenetic

relationships through modern experimental methods using comparative

anatomy, cytogenetics, ecology, morphology, molecular data, or other data”

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Objectives of Taxonomy

Determining what is a species (or their sub-divisions, as subspecies)

Distinguishing these species from others through keys and descriptions

and geographic boundaries and mapping their distributions

Investigating their interrelationships, and

Determining proper names of species and higher order ranks using

international rules of nomenclature.

In addition, some taxonomists investigate processes of evolution that lead

to the existing pattern of species and their interrelationships.

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Why Classification

Around 400000 plant species are reported in the world now (Stearn, 1980)

The World Conservation Union’s (IUCN) Red List of Plants included some 34,000

threatened species in 1997.

60,000 to 100,000 plant species are currently threatened

75% of the world’s population relies on traditional medicines.

Globally, 80% of our plant based calorie intake comes from just 12 domesticated

plant species (8 cereals,4 tubers) though 30,000 species of plant are edible.

Need to study about all plants and for:

o Know about the ecosystem

o Conserve biodiversity

o Proper management

o Scientific study

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Taxonomic System

Artificiel

300 BC. – 1735 AD.

Natural

1600- 1883 AD.

Phylogenetic

1883- Now AD.

Classification Systems

Some literature said about another type termed as Mechanical Classification

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Artificiel classification

Oldest and first approach of classification of plants.

Can not describe all plants

Classification of plants into different taxa based upon one or few characteristics of

plants which is selected by authors. Such as,

Reproductive behavior

Physical appearances,

Habitat

Phenology

Cotyledon etc.

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Some important artificial system

1. Vedas ( ar. 200 BC.)

2. Theophrastus ( 370-285 BC.)

3. Secundus (23-79 AD.)

4. Dioscorides (62-128 AD.)

5. Magnus (1200-1280 AD.)

6. Brunfels ( 1464-1553 AD.)

7. Bock (1489-1554 AD.)

8. Fuchs ( 1501- 1556 AD.)

9. Tournefort (1656-1708 AD.)

10. Linnaeus (1707-1778 AD.)

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SL No Name Classification parameter

01 Vedas

200 BC

Religious importance, use, medicine,

flowering and fruiting. Etc.

02 Theophrastus

ca. 300 B.C.

Size and life time(herbs, shrubs and trees)

03 Herbalists

1470-1670

Medicinal values

04 Tournefort

1700

Flower and fruit giving rise (Innovator of

genus. Distinction between genus and

species.)

05 Linnaeus

1735

Sexual behavior of plants (number, length

and union of stamens and carpels)

Basis of some artificial classification system

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Advantages and disadvantages of Artificial classification

Advantages

Simple and easy

Need short time and information

Poorly known plant can be placed easily

Need very few instruments

Specifically focus on properties of interest

Disadvantages

Can not grouped all plant perfectly

Little predictive value

Arbitrarily selected properties do not necessarily correlate well with each other

Cannot describe evolution

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Linnious system of classification

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Natural classification

This taxonomic system was introduced by Jean Bauhin in 1623.

These systems are based on natural affinities of plants.

It is done based on natural characteristics of plant.

It place together organisms that have the greatest number of shared features.

No single feature is not important but total features are the tools of classification.

So, classification of plants which is done based on maximum natural characteristics of

plants and not a single characteristic but total characteristics act as the key to place a

plant into a definite texa is termed as natural system of plant classification.

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Some important natural classification system

1. Gaspard Bauhin (1550-1624)

2. Ray ( 1627-1 705AD.)

3. Adanson (1727-1806)

4. A. L. de Jussieu ( 1748-1836)

5. Robert Brown ( 1773-1858)

6. A.P. Candole (1778-1884)

7. Alphonse (1806-1893)

8. Benthum ( 1800-1884) and Hooker (1817-1911)

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Sl No Name Classification parameter

01 A. L. de Jussieu

( 1748-1836)

• No of cotyledon

• Presence and absence of petals

• Position of petals and stamens

02 Robert Brown

( 1773-1858)

Tissue structure

03 A.P. Candole

(1778-1884)

Characteristics of vascular tissue

04 Benthum

( 1800-1884) and

Hooker (1817-1911)

Seed characteristics of plants

Basis of some Natural classification system

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Advantages and disadvantages of Natural classification

Disadvantages

Complex than artificial

Need long time and more information

Poorly known plant can not be placed easily

Can not focus specifically on properties of interest

Advantages

More satisfactory on placing of species

More predictive value

Arbitrarily selected properties are necessarily correlate well with each other

can be used to predict properties, not related the classification

Contains more information about a species

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Comparison of natural and artificial classification

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Phylogenetic classification

Latest system of classification of life.

Done in very micro scale(cells)

Basic of the system is the Darwin's “Origin of Species (1859)”

First introduced by August Wilhelm Eichler in 1883.

Goal of the system is to establish a system of classification based on the

course of evolutionary descent of its members.

System where it is believed that every species is come from the evolutionary

change.

So it is defined as the classification system based on phylogenetic characteristics

of a species.

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Some important natural classification system

Hutchinson (1884-1972)

Takhtajan (1980)

Cronquist (1981)

Dahlgren (1981)

Thorne (1981)

APG (Angiosperm Phylogeny Group

system) (1998,03,09)

Eichler (1839-1889)

Engler (1844-1930)

Prantl (1849-1893)

Bessey (1845-1915)

Wettstein (11862-1931)

Sokal & Sneath (1963,73)

Henning (1966)

Hallier (1868-1938)

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Advantages and disadvantages of phylogenetic classification

Advantages

unique name for each species eliminates confusion

Maximum predictive value

Maximum detail scientific study

Contains maximum information about a species

Disadvantages

Most Complex than others

Need long time and research

Physical appearances are neglected

Physically same species can be in different groups

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Most widely accepted systems

Arificial classification

Theophrastus ca. 300 B.C.

Linnaeus (1707-1778 AD.)

Natural classification

Benthum ( 1800-1884)

and Hooker (1817-1911)

Phylogenetic classification

Hutchinson (1884-1972)

Takhtajan (1980)

APG (Angiosperm Phylogeny Group

system) (1998,03,09)

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Modern classification system

NaturalPhylogenetic

Now Phylogenetic and natural classification system is combined to classification of

plants

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Modern Classification

BC AD 1500 1600 1700 1800 1900 2000

Artificial

Natural

Phylogenetic

Historical Development of plant Taxonomic System

Bessey

1915

Sokal &

Sneath

1963,73

Henning

1966

APG

1998,03,09

Theophrastus

ca. 300 B.C.

Herbalists

1470-1670

Tournefort

1700

Linnaeus

1735

Bauhin

1623

Ray

1686-1704

Jussieu

1789

Candolles

1824- 73

Bentham &

Hoker

1962

Adanson

1763

Eicher

1883

Engler &

Prantl

1887-

1915

Hutchinson

1926- 69Takhtajan

1969-97

Throne

2000

Dhlgren

1975-89

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Bibliography

1. Jeffrey, C. (1982). An introduction to plant taxonomy (Second edition ed.).

(C. Jeffery, Ed.) New York, United State: Cambridge University Press.

2. Sharma, O. P. (2007). Plant Taxonomy. 7 west Patel Nagar, New Delhi,

India: Tata McGraw-Hill Publishing Company Limited.

3. Stearn, W. T. (1989). Botanical Latin. (C. a. David, Ed.) London, Great

Bratin: Redwood Burn limited Trowbridge & Esher for David and Charls

limited.

4. Stewart, M. (2008). Classification of Life. 241 First Avenue North, U. S. A:

Minneapolis.

5. Stuessy, T. F. (2009). Plant Taxonomy (Second ed.). New York, U. S. A.:

Columbia University Press.

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Question???

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