TYPES OF CLASSIFICATION IN TAXONOMY

Types of classification

The different types of classification proposed by earlier taxonomists can be broadly categorized into three systems– artificial, natural and phylogenetic.

Artificial system

It was based on one or at most only a few superficial characters.  In 1753, Carolus  Linnaeus  of Sweden published his book “ Species Plantarum”  wherein he described 7,300 species.  He divided the plants into 24 classes based on number, union, length and certain other characters of stamens.   Hence, this system is also known as sexual system of classification.

In those days, it was an important over other systems of classification.  The importance of floral characters was felt by Linnaeus and his classification was more important than others. The main defect of this system is that totally unrelated plants are brought together in a single group and those that are closely related plants are placed in widely separated groups.   For example, plants belonging to Zingiberaceae of Monocotyledons and that of Anacardiaceae of Dicotyledons had been placed in one group called Monandria, as these possess only one stamen. Another defect  of  this  system  was  that  no importance was given to either natural or phylogenetic relationships among different groups of plants.

 TYPES OF CLASSIFICATION  – NATURAL SYSTEM

The explanation about natural system in classification of taxonomy is provided below

Natural system

In this system of classification, plants are classified based on their natural affinities. More number of characters are taken into consideration in this system. It is mainly based on all the informations that were available during the time of direct observation of plants. The most important natural system of classification of seed plants was proposed by two British botanists George Bentham  and Sir Joseph Dalton Hooker.  It helps to determine the relationships between various groups of plants.  However, it does not attempt to bring out evolutionary relationships among different groups of plants.

TYPES OF CLASSIFICATION – PHYLOGENETIC SYSTEM

Phylogenetic system

This system is based on evolutionary sequence as well as genetic relationships among different groups of plants. In addition to this, it employs as many taxonomic characters as possible. Charles  Darwin’s concept of Origin of Species had given enough stimulus for the creation of phylogenetic system of classification. Adolf Engler (1844-1930) and Karl Prantl (1849-1893) of Germany published a phylogenetic system in their monograph on “Die Naturlichen Pflanzen Familien”. In this system, floral characters such as single whorl of perianth or no perianth and unisexual flowers pollinated by wind were considered as primitive characters when compared to perianth with two whorls, bisexual flowers pollinated by insects.  According to them, members of Asteraceae of dicotyledons and Orchidaceae of monocotyledons were highly advanced.

QUESTIONS :

1. What is natural system?
2. Explain in detail about types of classification?
3. explain briefly the classification of taxonomy?
4. What is artificial system?
5. What is Phylogenetic system?