This document summarizes several systems of plant classification including artificial, natural, and phylogenetic systems. It provides details on Linnaeus' artificial classification system based on plant sexuality and number of sexual parts. It also describes Bentham and Hooker's widely adopted natural system from 1862-1883, and Engler and Prantl's phylogenetic system from 1887-1915 which was based on evolutionary relationships and classified plants into 13 divisions.

1. Systems of Plant classification
By
Dr P B MALLIKHARJUNA
Associate Professor
GFGC YB

2. Plant classification is the placement or arrangement of plants or
plant groups in an orderly sequence according to phenetic
phylogenetic relationships or criteria that are more artificial.
Species is the basic unit of classification
Indeed more than 50 different systems of classification for
been proposed to date. Of these, only few are dominant and
different parts of the world. However, no system is completely
in reflecting the phylogenetic relationship of the taxa concerned.
system is superior over the other to a degree. Further an ideal
should be easy to adopt, stable and aid to memory predictive
concise.
All these classifications based on the criteria they have
into any one of the following systems i.e.,
Artificial system of classification
Natural system of classification

3. Artificial system of classification
These are the first category and primitive type of classifications
based on the Aristotelian approach.
In the artificial system of classification, the plants have been
classified based on the presence or absence of a single or few
arbitrarily selected and easily observable characters.
Owing to this, in several cases closely related plant species are
placed in different groups and unrelated plants are kept together.
Ex: 1) Theophrastus Classification, who has proposed an
artificial classification for the plants. He has classified plants based
on habit into four groups namely herbs, undershrubs, shrubs and
trees.

4. Linnaeus classification:
Linnaeus had proposed a well-known classification of plants. It is an artificial
system of classification based on the sexuality of plants.
• Proposed an Artificial system of classification based on the number
and arrangement of sexual parts.
• He has recognized the importance of flowers and fruits in the
classification.
• He has recognized 24 classes determined based on number, size and
union of stamens.
Class: 1) Monadria 13) Polyandria
2) Diandria 14) Didynamia
3) Triandria 15) Tetradynamia
4) Tetrandria 16) Monoadelphia
5) Pentandria 17) Diadelphia
6) Hexandria 18) Polyadelphia
7) Heptandria 19) Syngenosia
8) Octandria 20) Gynandria
9) Ennendria 21) Monoecia
10) Decandria 22) Dioecia
11) Dodecandria (11 – 19) 23) Polygamia
12) Icosandria (20) 24) Cryptogamia
• This classification was in practice for over 75 years until the natural
systems of de Jessieu and de Condolle come into existence.

5. Natural system of classification
In natural system, all the important morphological characters of the
plants are taken into account to judge their natural resemblance and
relationships. The plants are thus, classified according to their natural
relationships. In this system, the plants were first grouped into large higher
categories and then these categories are further divided and subdivided until
the basic category called the species is reached. These are very useful in the
identication of plants.
Ex: 1. de Condolle system of classification
2. Bentham and Hooker’s system of classification.

6. Phylogenetic system of classification
These are the modern and recent system of classifications. The
arrangement of plants or plant groups are mainly classified in the light of
phylogenetic relatedness or the Evolutionary relationships among the
plants. These classifications are based on the several characters of the
plants such as morphological, anatomical, cytological, karyological,
embryological, ecological and biochemical characters taken into account.
Further, plant characters are weighed in the evolutionary context. For
instance, arborescent habit is primitive over herbaceous habit.
Ex: Engler and Prantl system of classification
Cronquist classification
Thakthajan classification
APG (Angiosperm Phylogeny Group) classification

7. BENTHAM & HOOKER’S
CLASSIFICATION
(1862-1883AD)
 George Bentham and Joseph Dalton Hooker were British naturalists proposed the
widely adopted natural system of classification for the seed plants in Genera
plantarum in the Latin, published in three volumes (1862-1883 AD).
 It is the most widely adopted natural system of classification for the study of the
flowering plants.
 It included names, description, illustrations, and nomenclature of seed plants
(97205 species known at that time).
 The basis for this classification are de Jesseue and de Condolle’ classifications.
 It is post-Darwinian in publication and pre-Darwinian in concept.
 This classification is mainly based on the several morphological arbitrarily
selected characters.

8.  They have classified the division-
Phanerogams (flowering plants) into 3
classes containing 202 families with 7569
genera and 97205 species.
 They have placed the order Ranales in the
beginning of the dicots which are
universally considered to be the most
primitive angiosperms.
 They believed in the theory of reduction in
evolution.

10. Merits:
 It is the widely used natural system of classification in pedagogic
deliberations
 There is a uniform treatment and the study judgement of taxa
throughout the system.
 Placing the order Rannales in the beginning is justified, as several
taxonomists believed that are primitive evolutionary.
 Placing dicots before the monocots is justified.
 Even though the system is not phylogenetic, the sequence of
arrangement of taxa reflect the lines of evolution.

11. Demerits:
 Placing/interpolation of Gymnosperms in-between Dicots and Monocots is a
major drawback.
 Division of Dicotyledons into 3 sub-- classes based on a single character i.e.,
Perianth has become a priori method of character weighing.
 The sub-class monochlamydeae of the dicots is an unnatural assemblage.
 Related families are kept apart such as Chenopodiaceae and Caryophyllaceae.
Further, unrelated families kept together such as Juncaceae and Palmae
 The authors were believed in the dogma of fixity of species and immutability of
species.
 Placing the family Orchidaceae at the beginning of monocots is not justified as
it is one of the highly evolved one.

12. ENGLER & PRANTL CLASSIFICATION
( 1887-1915)
•Adolf Engler and Karl Prantl were the German botanists.
•They have proposed a phylogenetic and polyphyletic system of
classification for the entire plant Kingdom i.e., from algae to
angiosperms.
•They have published their classification in a 23 (Voluminous) magnum
opus entitled “Die Naturlichen Pflanzen familien” (i.e., The natural
plant families) between 1887 - 1915 in German language.
•This system is based on the foundations laid down by AW Eichler.
•They suggested the Amentifer theory in the interpretation of the origin
of angiosperms.
•According to them the arborescent (woody) habit with unisexual and
wind pollinated flowers produced in catkin inflorescence are primitive.

13. •They have classified the plant Kingdom into 13 divisions out
ofthese one to 12th division includes the non flowering plants
•The 13th division includes the flowering plants or seed
plants has Embryophyta Siphanogama
•This division Embryophyta Siphanogama has 2 sub
divisions namely Gymnospermae and Angiospermae.
•The subdivision Gymnospermae has 7 classes.
•Whereas, the sub division Angiospermae has 2 classes
(Monocotyledoneae and dicotyledoneae ) , 55 orders and
306 plant families.
•The class Monocotyledoneae was further divided into 11
orders starting with Pandanales (Typhaceae) and ending with
Microspermae (Orchidaceae).

14. •The class Dicotyledoneae further divided into 2 sub classes namely
Archichlamydeae & Metachlamydeae / Sympetalae , with 44 orders
including 261 families.
•The subclass Archichlamydeae contains the 33 orders and 201 families
beginning with Verticillatae (Casuarinaceae) and ending with the order
Umbelliflorae (Apiaceae).
•The second subclass, Metachlamydeae contains 11 orders and 60
families starting with Diapensiales (Diapensaceae) and ending with
Companulatae (Composite).

16. Merits:
•Placing Gymnosperms before the Angiosperms was justified
•Placing Monochlamydeae and Polypetalae plant families in the
Archichlamydeae is more homogeneous.
•Keeping the both Asteraceae and Orchidaeae families at the
respective ends of dicots and monocots is justified.
•The taxa are extensively illustrated and also provided modern keys
to the Genera and families.
•The work is known for its systematic thoroughness with which it is
applied to the world's flora.
•They have taken the anatomical and embryological data along with
morphological attributes in the light of evolution while classifying
the plants.

17. Demerits:
•Placing monocots before to the dicots he is contradictory to the generally
accepted line of evolution of angiosperms. However it is rectified in the
later edition 11th edition (deals 1926).
•The system failed to be a truly phylogenetic one.
•This system is not a much of practical utility